Enlargement of the Cotter Reservoir and associated works

Transcription

1 Enlargement of the Cotter Reservoir and associated works Final public environment report 2008/4524 August 2009

2 Contents EXECUTIVE SUMMARY 1 1 INTRODUCTION Overview Context Objectives Scope and legislative basis of the PER Studies, surveys and consultations to inform the proposal Summary of priority environmental and management issues Responsibilities for preparing the PER Structure of the PER 24 2 BACKGROUND Background to the proposal The future of the Cotter Reservoir Relevant statutory and planning instruments and important Government guidelines Monitoring enforcement and review procedures Relation of the proposal to other actions 36 3 LOCATION AND TENURE Location of the proposal The Cotter River catchment Tenure Areas of conservation value and the location of known listed threatened species 43 4 PROPOSAL JUSTIFICATION AND NEED Proposal justification and need Proposal objectives Objectives and principles of the EPBC Act Consequences of not proceeding 61 5 OPTIONS AND ALTERNATIVES Options for the next ACT water source Assessment of social, economic and environmental parameters Future Water Options 2007 review Cost benefit analysis ACT Government decision major water security initiatives 78 6 DESCRIPTION OF THE PROPOSAL General description Scope of works Design Construction Inundation Operation Decommissioning Down stream changes in water flows Upstream changes in water flow Changes in the management of water resources in the Cotter River system Cumulative impacts of ACTEW s Water Security Program 108

3 7 ENVIRONMENTAL VALUES AND MANAGEMENT OF IMPACTS: TERRESTRIAL Introduction to the listed threatened species Existing environment Potential impacts of the action Proposed mitigation and management measures Significance assessment Impact assessment outcomes ACT offset strategy Monitoring and reporting ENVIRONMENTAL VALUES AND MANAGEMENT OF IMPACTS: AQUATIC Introduction to the listed threatened species Existing environment Potential impacts Risk analysis of potential impacts Proposed management and mitigation measures Significance assessment Impact assessment outcomes Translocation strategy Current research and monitoring Proposed research, monitoring and reporting COMMUNITY CONSULTATION Consultation to date Proposed consultation about relevant impacts of the action Consultation regarding the proposed action Impacted communities Record of consultation CONCLUSION REFERENCES GLOSSARY AND ABBREVIATIONS APPENDICES Appendix A Cross reference table Appendix B Studies B.1 Specialist Terrestrial Ecology Report. B.2 Constructed homes for threatened fishes in the Cotter River catchment: Phase 1 Report. Appendix C Study team Appendix D Environmental record of the person proposing the action D.1 Person proposing the action D.2 Environmental record D.3 ACTEW s environmental policy and planning framework Appendix E ACTEW Corporation referral documentation

4 Appendix F Detailed legislation F.1 Commonwealth legislation F.1 ACT legislation F.1 Commonwealth and ACT Government policies Appendix G Consultation Appendix H PER guidelines

5 List of tables Table ES.1 Water supply options. 5 Table ES.2 Overall program of works. 13 Table 1.1 Scope of works summary. 15 Table 1.2 PER structure. 24 Table 2.1 List of the approvals required for the proposal. 30 Table 2.2 Objectives and targets. 34 Table 3.1 Land that may be affected by the proposal. 41 Table 4.1 Proposed enlargement of the Cotter Reservoir assumptions and performance. 50 Table 4.2 Criteria for new water supply assets. 53 Table 4.3 Previous and revised costs of water restrictions ($ million/yr). 53 Table 5.1 Options identified in Options for the Next ACT Water Source. 62 Table 5.2 Sustainability criteria for evaluation of Future Water Options (ACTEW, 2005b). 63 Table 5.3 New reservoir in the Cotter catchment summary of performance. 66 Table 5.4 Tennent Reservoir summary of performance. 67 Table 5.5 Tantangara Transfer summary of performance. 68 Table 5.6 Angle Crossing option (Murrumbidgee to Googong) summary of performance. 69 Table 5.7 Seawater source summary of performance. 70 Table 5.8 Groundwater summary of performance. 70 Table 5.9 Water purification scheme summary of performance. 71 Table 5.10 Stormwater use summary of performance. 72 Table 5.11 Rainwater collection (private tanks) summary of performance. 73 Table 5.12 Grey water use summary of performance. 73 Table 5.13 Other non-potable reuse options (large scale irrigation) summary of performance. 74 Table 5.14 Accelerated demand management summary of performance. 75 Table 5.15 Cloud seeding summary of performance. 76 Table 5.16 Watermining TM summary of performance. 77 Table 5.17 Evaporation control on reservoirs summary of performance. 77 Table 6.1 Estimated vegetation type and loss due to actions relating to the construction of the main dam wall and ancillary structures. 88 Table 6.2 Estimated total vegetation loss at maximum reservoir capacity. 90 Table 6.3 Short and long term modelled flow projections for downstream Cotter Reservoir. 95 Table 6.4 Flow statistics for Murrumbidgee River at Mt MacDonald. 96 Table 6.5 Short and long term modelled flow projections for downstream Bendora Reservoir. 99 Table 6.6 Bendora Reservoir drawdown statistics for the short and long term (metres below spillway). 104 Table 6.7 Statistics for supply from the Cotter Reservoir. 105 Table 6.8 Statistics for Bendora Reservoir supply. 106 Table 6.9 Statistics on Corin Reservoir releases and spills with and without the proposal. 107 Table 6.10 Short and long term modelled flow projections for downstream of the Cotter Reservoir. 109 Table 6.11 Short and long term flows in the Murrumbidgee River at Mt MacDonald. 111 Table 7.1 Summary of knowledge gaps, associated risks and proposed management. 121 Table 7.2 Indicative cost of implementing offset strategy measures. 129 Table 8.1 Location of current and recent populations of Macquarie Perch (NSW Department of Primary Industries, 2008). 133 Table 8.2 Locations of important populations of Murray Cod as identified by the National Murray Cod Recovery Team (note: population numbers have not been indicated as the data has not been collected). 140

6 Table 8.3 Evidence of breeding and location of current and recent populations of Trout Cod (Trout Cod Recovery Team, 2008a & 2008b). 147 Table 8.4 Environmental protection objectives for the threatened aquatic species. 151 Table 8.5 Ecological objectives for selected ACT aquatic ecosystems (as specified under the Environmental Flows Guidelines (ACT Government, 2006). 152 Table 8.6 Comparison of physical characteristics of the existing and proposed enlargement of the Cotter Reservoir. 153 Table 8.7 Risk assessment matrix with likelihood, consequence and risk rating. 155 Table 8.8 Qualitative measures of likelihood scale. 155 Table 8.9 Qualitative measures of the consequences scale. 155 Table 8.10 Risk assessment results for Macquarie Perch, Murray Cod and Trout Cod. 156 Table 8.11 A list of significant knowledge gaps and their management for the proposal. 174 Table 8.12 Indicative cost estimates for mitigation measures. 176 Table 8.13 Indicative cost of implementing the translocation strategy. 185 Table 8.14 Objectives and indicators from the ACT Environmental Flow Guidelines (ACT Government, 2006). 195 Table 8.15 Fish monitoring program design. 197 Table 9.1 Consultation with authorities in relation to the EIS Request for Scoping Document. 204 Table 9.2 Consultation activities undertaken for the draft EIS. 205 List of figures Figure ES.1 Location of the proposal. 2 Figure 1.1 Artist s impression of the proposal viewed from Moores Hill five (5) years post construction. 14 Figure 1.2 Moving average inflows to Corin, Bendora and Googong Reservoirs. 16 Figure 2.1 Framework environmental management system. 33 Figure 3.1 Location of the proposal. 39 Figure 3.2 Lower Cotter catchment land use and access trails. 40 Figure 3.3 Land potentially affected by the proposal. 42 Figure 3.4 Conservation values. 44 Figure 4.1 Long term inflows into Corin, Bendora and Googong Reservoirs ( ). 51 Figure 4.2 Annual inflows into Corin, Bendora and Googong Reservoirs ( ). 51 Figure 4.3 Projected storage with climate continually repeating. 54 Figure 4.4 Projected storages with repeated 2006 climate. 55 Figure 6.1 Concept diagram of the main engineering infrastructure and construction area. 83 Figure 6.2 Indicative construction area at clay borrow sites. 84 Figure 6.3 Construction cycle for the main dam proposed RCC construction process. 85 Figure 6.4 Concept diagram of the delivery of RCC to the dam conveyor (swinger) layout. 86 Figure 6.5 Concept diagram of the layout of the tower crane (and showing spans over the proposed main dam wall). 87 Figure 6.6 Comparison of the existing and proposed Cotter Reservoir inundation areas. 89 Figure 6.7 Monthly total flows downstream of the Cotter Reservoir for January 1999 to January Figure 6.8 Downstream of Cotter Reservoir flow duration curve for the existing and proposed reservoirs ( ). 93 Figure 6.9 Monthly predicted flows downstream of Cotter Reservoir with and without the proposal. 94 Figure 6.10 Flow duration curve for flows in the Murrumbidgee River at Mt MacDonald. 96 Figure 6.11 Historical monthly total flows downstream of the Bendora Reservoir for January 1999 to January Figure 6.12 Flows downstream of the Bendora Reservoir 2011 to Figure 6.13 Monthly Predicted flows downstream of Bendora Reservoir with and without the proposal. 99

7 Figure 6.14 Operating Rules with the existing Cotter Reservoir. 101 Figure 6.15 Preliminary draft operating rules with the proposal (based on results from modelling). 102 Figure 6.16 Percentile curve for level in Bendora Reservoir with and without the proposal. 103 Figure 6.17 Modelled Bendora Reservoir end of month drawdown level with and without proposal. 104 Figure 6.18 Supply from the Cotter Reservoir with and without the proposal. 105 Figure 6.19 Supply from Bendora Reservoir with and without the proposal. 106 Figure 6.20 Releases and spills from the Corin Reservoir. 107 Figure 6.21 Downstream of Cotter Reservoir flow duration curve ( ). 109 Figure 6.22 Flow duration curve for the Murrumbidgee River at Mt MacDonald ( ). 110 Figure 7.1 Vegetation communities. 113 Figure 7.2 Known locations of Pink-tailed Worm Lizard (A. parapulchella). 116 Figure 7.3 Known locations of Pale Pomaderris (P. pallida). 118 Figure 8.1 Indicative historical and present range of Macquarie Perch in Australia (Source NSW Department of Primary Industries, 2008). 134 Figure 8.2 Indicative distribution of Macquarie Perch within the ACT. 136 Figure 8.3 Indicative historical and present range of Murray Cod in Australia (NSW Department of Primary Industries, 2008). 139 Figure 8.4 Indicative distribution of Murray Cod within the ACT. 143 Figure 8.5 Indicative historical and present range of Trout Cod in Australia (Source NSW Department of Primary Industries, 2008). 146 Figure 8.6 Indicative distribution of Trout Cod within the ACT. 149 Figure 8.7 Plot of the modelled results indicating the cumulative percentage of time the water level in the enlarged reservoir will spend above various levels below the full supply (water) line. 164 Figure 8.8 Artificial habitats being erected for monitoring trials in Cotter Reservoir during 2008 (ActewAGL, 2009b). 165 Figure 8.9 The successful Vanity s Crossing fish way (ActewAGL, 2009b). 168 Figure 8.10 Macquarie Perch spawning habitat. 172 Figure 8.11 Research projects associated with the implementation of the ECD Fish Management Plan. 187 Figure 8.12 Process for updating the ECD Fish Management Plan based on results of monitoring. 192 Figure 8.13 Long term timeline for adaptive management during the delivery of the proposal. 193

8 Executive summary Title of the proposal: Enlargement of the Cotter Reservoir and associated works. Proponent: ACTEW Corporation Limited. Address: GPO Box 366, Canberra City, Australian Capital Territory Agent: Mark Sullivan, Managing Director ACTEW Corporation Limited. Overview The enlargement of the Cotter Reservoir (hereby referred to as the proposal and the Enlarged Cotter Dam ) is one of a suite of initiatives developed by ACTEW Corporation Limited (ACTEW) to secure the future water supply of the Australian Capital Territory (ACT) and surrounding region. The proposal was announced by the ACT Government in October 2007, recognising the necessity to expand the existing water supply infrastructure to withstand the effects of ongoing drought conditions and associated low inflows into ACT reservoirs. The delivery of the proposal will be undertaken through the Bulk Water Alliance (BWA), a consortium consisting of ACTEW (owner), ActewAGL (owner operator), GHD (design), John Holland and Abigroup (construction). In October 2008, ACTEW referred the proposal to the Commonwealth Minister of the Department of Environment, Water, Heritage and the Arts (DEWHA) as required under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999). DEWHA determined the proposed action to be a controlled action and requested a Public Environment Report (PER) be prepared to further assess the potential impact on relevant matters of national environmental significance under the EPBC Act Background The proposal is required to deliver a more secure water supply for the ACT and surrounding region. The proposal will increase the capacity of the Cotter Reservoir from four (4) gigalitres (GL) to 78GL, raising the ACT s overall storage capacity by one third. The proposal was determined and chosen from a range of options because of its relative economic and social benefit to the community, reliability of large scale water supply and low environmental impacts. The proposal involves the construction of a new dam wall and associated infrastructure (both permanent and temporary) such as saddle dams, quarries, sediment basins, coffer dam, diversion channels, reservoir mixers, crushing plant, batch plants, stockpiles, workshops, office compounds and site roads. The proposal has been actively progressed by ACTEW through submission of a draft Environmental Impact Statement (EIS) in October A revised EIS was amended and submitted following comments to the ACT Planning and Land Authority (ACTPLA) on 17 February A Section 224 Notice (report) was subsequently submitted to ACTPLA on 8 May The final EIS was approved by the ACT Planning Minister on 19 June ACTEW have successively lodged a development application (DA) for planning and development approval to ACTPLA. As assessment as part of the preparation of this PER was undertaken for the listed threatened species against the EPBC Act Policy Statement 1.1 Significant Impact Guidelines Matters of National Environmental Significance (Department of Environment Water Heritage and the Arts, 2006). The assessment concluded that the proposal is not likely to have a significant impact on the relevant threatened species listed under the Act. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/4524 1

9 Figure ES.1 Location of the proposal. 2 WATER SECURITY MAJOR PROJECTS AUGUST 2009

10 Location and tenure The existing Cotter Reservoir is located on the Cotter River in the Lower Cotter catchment approximately 18 kilometres (km) west of Canberra. The area is part of a broader recreational precinct that includes Cotter Avenue, Cotter campground, Casuarina Sands and the Cotter Pumping Station. The proposal will be constructed approximately 125 metres (m) downstream of the existing Cotter Reservoir. The specific area covers approximately 1,451 hectares (ha) and represents approximately 8 per cent of the entire Lower Cotter catchment. The area impacted by the proposal is largely modified due to the existing Cotter Reservoir and upstream Bendora and Corin Reservoir systems, previous pine plantation operations and the effects of the damage caused by the 2003 bushfires. All land within the proposal area is unleased Territory land. The local environment contains deeply incised river valleys along the Cotter, Paddy s and Murrumbidgee Rivers. The surrounding elevated lands to the east and west above the river valleys and gorges comprise generally gently undulating hills. Figure ES.1 provides the regional location of the proposal in the ACT. Proposal justification and need The ACT Government released a report titled Think water, act water a strategy for sustainable water resources management in The report looked at all aspects of ACT water resources and identified a series of objectives to guide sustainable management of water resources in the ACT. The key challenge for the ACT in the medium and long term is to build additional water supply assets that can cope with reduced average inflow into the reservoirs and longer, more frequent droughts, without having to impose high level water restrictions on the community for extended periods. The following criteria were identified for the development of new water supply options capable of meeting this challenge: Maximising the use of existing service infrastructure, both ACTEW s and others. Increasing the diversity of sources of water (both rainfall and rainfall independent options). Ensuring that adopted choices include at least one (1) source of water which is not dependent on rainfall in ACTEW s water supply catchments. Maximising operational flexibility to provide backup capabilities in the event any part of the system is out of operation for whatever reason. Providing a net economic benefit to the community. Optimising outcomes from capital and operational costs and minimising the consequent flow-on cost to consumers. Minimising the environmental impact of the water supply solutions. In response to Think water, act water a strategy for sustainable water resources management, ACTEW launched the Future Water Options proposal in , which investigated the viability of future water supply options in terms of these six (6) key assumptions: The ACT Government s water conservation targets will be met. The environmental flows will be delivered according to ACT Government guidelines. The rehabilitation of the catchment will respond to bushfires. The population will continue to grow according to the ACT Government s Spatial Plan. ACTEW will meet its service obligations to customers. The projections of climate change and climate variability will occur in accordance with predictions made at that time. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/4524 3

11 Thorough investigations over four (4) years led to the identification of the Enlarged Cotter Dam as one of the proposals recommended by ACTEW as an important initiative needed to secure the ACT and region s water supply by: Delivering a net economic benefit to the community. Having minimal impact on threatened fish populations. Providing environmental benefits through improved catchment conditions and an enhanced understanding of habitat and opportunities for endangered species within and in the vicinity of the reservoir. Using existing infrastructure via the pump station at Lower Cotter and the Mt Stromlo Water Treatment Plant. Drawing water from a reliable catchment (Cotter River) in times of drought. Capturing environmental flows that are released from the Corin and Bendora Reservoirs that often spill over the current Cotter Reservoir. Generating economic benefits as a result of construction and the expertise that it will bring to the ACT. Providing to economic and social benefits to the community derived from spending less time subjected to water restrictions. Options and alternatives In the planning and selection of new water supply assets for the region, ACTEW assessed all relevant options, both large and small scale as well as localised, to ensure a solution that will deliver water security through a diverse range of measures. Each option was assessed against Triple Bottom Line (TBL) criteria and was developed to yield the best options for recommendation to the ACT Government. A summary of these outcomes is provided in Table ES.1. 4 WATER SECURITY MAJOR PROJECTS AUGUST 2009

12 Table ES.1 Water supply options. Option Social Economic Environment New reservoir in the Cotter Catchment Existing reservoir site on Territory land. Positive community sentiment arising from a reliable water supply. No increase in diversification. Impacts on landscape and visual amenity. Disturbance to community during construction, particularly road users, local residents and users of recreational facilities within and adjacent to the Cotter precinct. Requires appropriate management of heritage and cultural values High yield at relatively low cost. Provides net economic benefit through less frequent occurrence and severity of water restrictions. Creates local employment opportunities. Comparatively reliable water supply. Requires pumping to Mount Stromlo Water Treatment Plant. Minimal environmental impacts. Largely disturbed area which has been heavily impacted by bushfire and previous forestry activities. Requires management of threatened fish species. Removal and inundation of native and exotic vegetation. Impacts on the habitat and potential habitat of threatened species. Greenhouse gas emissions associated with construction and operation of the reservoir. ENLARGEMENT OF THE COTTER RESERVO R AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/ Tennent Reservoir Positive community sentiment due to diversification. Largest reservoir option available. Uncertainty of future inflows. Leaseholder relocation necessary to provide protection to the reservoir. Catchment remediation necessary to protect water quality. Road relocation. Impacts on landscape and visual amenity. Requires consideration of heritage and cultural values. Longer timeframe to build and fill than proposal. Higher cost than proposal. Damming of an unregulated river. Flooding impact on the endangered Yellow Box woodlands. Impacts in aquatic and terrestrial ecology. Greenhouse gas emissions associated with construction and operation of the reservoir.

13 6 AUGUST 2009 WATER SECURITY MAJOR PROJECTS Option Social Economic Environment Tantangara Transfer Angle Crossing option (Murrumbidgee to Googong) Positive community sentiment due to diversification. Requires changing Snowy Hydro s operating license. Requires inter-jurisdictional approvals. Requires negotiations with owners of water entitlements. May require re-assessment of catchment activities and appropriate management practices. Risk to ACT water quality as contamination events upstream may occur without notification to ACTEW. Potential for protracted negotiations. Potential for changes to the recreational facilities available at Angle Crossing. Provides additional diversification. Requires inter-jurisdictional approvals. Requires negotiations with land owners. Disturbance to community during construction, particularly road users, local residents and landholders. Changes to local environment including noise levels and visual amenity. Potential for changes to the recreational facilities available at Angle Crossing. Cost effective. Improves use of Googong Reservoir. Evaporative and other losses through run of river delivery. Improved use of the Googong Reservoir. Time effective to implement. Extraction only permitted when there is sufficient flow in the Murrumbidgee River. Comparatively low environmental impact as no new reservoir will be necessary to store water. Requires installation of pumping infrastructure on the Murrumbidgee River and piping to transfer water to Googong Reservoir. Greenhouse gas emissions associated with pumping. Comparatively low environmental impact as no new reservoir will be necessary to store water. Impacts on Murrumbidgee River through the installation of pumping infrastructure.

14 Option Social Economic Environment Seawater Source Proven technology. Inter-jurisdictional approvals. Rainfall independent and therefore more reliable and consistent supply. Positive community sentiment due to diversification Higher construction and operating costs. Higher energy use and greenhouse gas emissions due to treatment processes and pumping uphill from the coast to the ACT. May impact aquatic and terrestrial ecology during both construction and operation. Requires disposal of salt brine. Installation of 100 kilometres (km) of piping infrastructure. Groundwater Positive community sentiment due to diversification. Risk of contamination due to surrounding land use practices. No large aquifers in or near the ACT. Transfer costs to the ACT network. Greenhouse gas emissions associated with extraction and pumping to the ACT. Depending on location, may impact aquatic or terrestrial ecology. Extraction may not be sustainable. ENLARGEMENT OF THE COTTER RESERVO R AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/ Water Purification Scheme Stormwater use Proven technology. Requires community understanding and support. Poor water quality. Large storages required. Provide water for the maintenance of recreational facilities including sports grounds, parks and ovals and other beneficial uses. Potential for positive impacts on landscape and visual amenity. Higher cost. May not be used in wetter periods. Less dependent on rainfall than a reservoir. Would assist in avoiding restrictions under extremely dry conditions in the future. Creates local employment opportunities. Local use of existing storages can be cost effective. The most cost effective systems are already implemented. Highly variable quantities. Creates local employment opportunities. Constructed in area already impacted by the Lower Molonglo Water Quality Control Centre. Higher energy use. Greenhouse gas emissions associated with treatment and supply. Provides some stormwater control. May impact aquatic or terrestrial ecology.

15 8 AUGUST 2009 WATER SECURITY MAJOR PROJECTS Option Social Economic Environment Rainwater Collection (private tanks) Greywater use Other non potable reuse options large scale irrigation Accelerated demand management Cloud seeding Supplement existing drinking water use. Poses a risk to public health if appropriate management is not adopted. Can be used safely in toilets and laundry. Care needed in handling due to potential health issues. Replaces use of potable water on gardens. Disturbance during installation of infrastructure. Provides water for the maintenance of recreational facilities including sports grounds, parks and ovals. Potential for positive impacts on landscape and visual amenity. Raises issues of equity of access to suitable recreational opportunities. More efficient use of water. Fast tracks ACT Government s existing program. Benefits current drought situation. Requires considerable community support. No additional long-term benefit. Negative community sentiment arising from uncertainty of water supply. Higher cost. Creates local employment opportunities. Rainfall dependent. Difficult to obtain large enough storage. Higher cost Ongoing maintenance. Reliability of supply based on household water use practices. Creates local employment opportunities. Higher cost. Reliable non potable supply. Creates local employment opportunities. Seasonal use of water. Creates local employment opportunities. Unproven technology. Reliability is not guaranteed, may increase rainfall or may not. Requires ongoing research by ACTEW, a process which may take several years. Reduces stormwater runoff. Reduces sewerage flows (and treatment costs). Could potentially maintain or provide habitat for aquatic or terrestrial ecology. Low environmental impact. Impacts on natural rainfall patterns and distribution.

16 Option Social Economic Environment Watermining TM Reduces drinking water demand. Further locations being investigated. Provides water for the maintenance of recreational facilities including sports grounds, parks and ovals. Potential for positive impacts on landscape and visual amenity. Raises issues of equity of access to suitable recreational opportunities. Higher cost. Seasonal use. Not a major supply option. Creates local employment opportunities. Greenhouse gas emissions associated with construction and operation infrastructure. Evaporation control on reservoirs Impacts the visual amenity of reservoirs. Does not provide any additional supply. Not cost effective. May impact aquatic ecology. ENLARGEMENT OF THE COTTER RESERVO R AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/4524 9

17 Of the options listed in the preceding table, the following are considered reliable future supply options which satisfy the six (6) planning assumptions: The enlargement of the Cotter Reservoir (the proposal). The transfer of water from the Murrumbidgee River to the Googong Reservoir. The implementation of a water purification scheme at Lower Molonglo Water Quality Control Centre. The storage and transfer of water from Tantangara Reservoir. The construction of Tennent Reservoir be retained as a longer term option. Many of the other options have a supporting role to play in reducing the demand for water, improving water efficiency or providing some additional supply on a localised or fit for purpose basis. After examining these options individually and in varying combinations against the criteria, ACTEW determined the proposal as a high priority option due to the following reasoning: It provides the greatest net economic benefit to the community. It will deliver amounts of water similar to those projected for the large Tennent Reservoir option, but at half the capital cost and with less risk. It can also be brought into operation more quickly. It was assessed by the fish impact study conducted by Lintermans (2005) as having the lowest environmental impacts of any of the reservoir options. It will make use of existing infrastructure via the pump station at Lower Cotter and the Mount Stromlo Water Treatment Plant. It will draw water from a catchment that is much more reliable in times of drought than the Tennent catchment or the Googong catchment. It will capture the environmental flows that are released from the Corin and Bendora Reservoirs, which often spill over the existing Cotter Reservoir. It will capture much of the overflow from storm events that the current reservoirs in the Cotter system cannot store. The proposal also meets the requirements of the Triple Bottom Line assessment. Description of the proposal The proposal includes the design, construction and operation of a main dam, two (2) saddle dams and associated works and infrastructure. The new dam wall will be approximately 8 0m high and the adjacent saddle dams will be built to an approximate height of 12 m and 16 m, respectively. The existing reservoir and 283 hectares (ha) of land will be inundated and a further 36 ha of land will be cleared for construction and temporary ancillary works. The design of the proposal, including the main dam wall, saddle dams, spillway, protection works, outlet works and upgrade works, are all based upon environmental conditions and planning issues related to the local area and its uses, technical factors and future operational requirements. All designs will be reviewed by the ACT Technical Regulator in accordance with the New South Wales (NSW) Dam Safety Committee to ensure safety and compliance with all legislation prior to construction commencing. Subject to approval, construction of the proposal is planned to commence in September Construction activities will impact approximately 21 ha of native and 35 ha of non-native vegetation. During construction of the proposal the existing Cotter Reservoir will remain operational in order to continue supply to Canberra and the region. The existing reservoir is also required in order to maintain key habitats for threatened aquatic species. 10 WATER SECURITY MAJOR PROJECTS AUGUST 2009

18 Once construction is completed and the reservoir fills (expected to take 2-6 years) an additional 92.5 ha of native vegetation and 139 ha of non-native vegetation will be inundated. While some areas contain moderate to good quality vegetation and potential suitable habitat for listed threatened species, the majority of the area impacted by the proposal is already highly disturbed due to previous land uses and the effects of the 2003 bushfires. These disturbed areas are not considered suitable potential habitat for listed threatened species. The new reservoir is intended to become an active reservoir characterised by fluctuating water levels, more frequent abstraction and a greater capacity to capture inflows from the upper Cotter River catchment. The reservoir will be operated in accordance with all operational licensing requirements and ACTEW s commitment to ongoing management and monitoring procedures. This approach will ensure a negligible effect on flows, both upstream and downstream of the proposal, as shown in system operation modelling undertaken in the catchment, and maintain the health and future viability of the surrounding environment. Statutory requirements As the Cotter Reservoir is located exclusively within the ACT, it is subject to statutory requirements at both Territory and Commonwealth levels. The proposal is subject to planning approvals under the ACT Planning and Development Act 2007, which requires the preparation of an EIS for all development proposals that are to be assessed under the impact track. The proposal is also subject to compliance with other relevant Territory legislation including the National Capital Plan, Heritage Act 2004, Environmental Protection Act 1997 and Fisheries Act The proposal is subject to the requirements of the EPBC Act 1999 for matters of national environmental significance. A referral to the DEWHA was submitted and the proposal was determined as a controlled action, which requires further assessment via a PER. The purpose of the PER is to identify the impacts on any listed threatened species and ecological communities associated with the proposal. Environmental impacts and mitigation The construction of the proposal has the potential to have an significant impact on threatened terrestrial and aquatic species listed under the EPBC Act 1999 and as such, was determined to be a controlled action. Threatened species that may be impacted by the proposal include: The vulnerable Pink-tailed Worm Lizard (Aprasia parapulchella). The vulnerable Pale Pomaderris (Pomaderris pallida). The endangered Macquarie Perch (Macquaria australasica). The vulnerable Murray Cod (Maccullochella peelii peelii). The endangered Trout Cod (Maccullochella macquariensis). The potential impacts include: Disturbance or removal of known or potential habitat. Inundation of spawning habitat and nursery grounds in Cotter River upstream of existing reservoir. Drawdown of the Cotter Reservoir affecting habitat and food availability. Reduced flows in Cotter River downstream of the new Cotter reservoir. Assessments carried out on the relevant listed threatened species against the EPBC Act Policy Statement 1.1 Significant Impact Guidelines Matters of National Environmental Significance (Department of Environment, Water, Heritage and the Arts, 2006), concluded that the proposed action, the enlargement of the Cotter Reservoir is not likely to have a significant impact on these species. ACTEW has developed a suite of management and mitigation measures including monitoring programs, habitat creation and offsets to ensure that the impact of the proposal on the listed threatened species is not ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

19 significant. This extends to ensuring the health and vitality of the wider environment and its preservation for future generations. The mitigation measures for the management of the listed terrestrial species include: Establishing the responsibilities for the rehabilitation program. Identifying, mapping and delineating any areas of environmental significance within the construction footprint. Installing exclusion zones to protect areas of potential habitat for the Pink-tailed Worm Lizard (Aprasia parapulchella) and Pale Pomaderris (Pomaderris pallida) where practical. Implementation of weed management strategies. Implementation of erosion, sedimentation and stormwater controls consistent with relevant guidelines. Collecting seeds and propagules of native species and propagate for use in future replanting and rehabilitation works. Recovering suitable felled trees within the inundation area and stockpile for use in restoration works. Rehabilitating and revegetating the areas disturbed during construction as soon as practicable. Creating artificial rock outcrop habitats within rehabilitated areas using any additional natural rock material extracted and unused during the process of dam construction. Undertaking monitoring of restored and rehabilitated areas to determine success and implement corrective action, such as targeted weed management or soil erosion control works. Conducting ongoing liaison with relevant stakeholders, such as Parks Conservation and Lands (PCL) a division within the ACT Department of Territory and Municipal Services (TAMS). In addition, whilst potential impacts upon these threatened terrestrial species will be adequately avoided, managed and mitigated, it has been agreed as part of the ACT EIS process that a reasonable sized area would be allocated for rehabilitation of native vegetation, to compensate for the permanent loss of terrestrial habitat resulting from the construction of infrastructure and the increased area of inundation. The mitigation measures for the management of the listed aquatic species include: Preventing the introduction of the epizootic haematopoietic necrosis (EHN) virus and Redfin Perch during construction through the implementation of suitable management plans. Providing artificial fish habitats to compensate for loss of macrophytes as cover. Minimising cormorant predation by maintaining suitable fish cover. Managing fish passage to provide continued access to spawning sites. Implementation of an appropriate fish monitoring program to guide the medium and long term management of fish assemblage in the new reservoir. Preventing the introduction of alien fish during construction through the implementation of suitable preventative management plans. Ensuring appropriate temperatures for releases from Bendora Reservoir to avoid incorrect temperature signals to fish during spawning. Preventing spillage incidents during construction through the implementation of suitable management plans. Preventing the introduction of alien fish during construction through the implementation of suitable preventative management plans. 12 WATER SECURITY MAJOR PROJECTS AUGUST 2009

20 Installing an aeration system to destratify the enlarged Cotter Reservoir to counteract oxygen depletion. Designing fish friendly infrastructure, including the appropriate treatment of finished quarry faces, to provide suitable fish habitat. Designing the off-take tower to avoid fish mortality. Managing construction site erosion and sedimentation through the implementation of suitable management plans. Conducting ongoing liaison with relevant stakeholders, such as ACT EPA and TAMS PCL where applicable. Community and stakeholder consultation ACTEW has undertaken a broad consultation program to gauge the opinions of the wider community on a range of water security issues since Consultation involved: Liaison with referral authorities to discuss the proposal and the scope of the Environmental Impact Statement (EIS). Public consultation with community groups and authorities during the preparation of the EIS and during public notification. ACTEW intends to continue an ongoing program of community and stakeholder consultation throughout the delivery of the proposal. Proposal timeline The proposal is currently in the planning and approvals phase with construction due to commence in September Table ES.2 provides the overall program of works for the proposal. Table ES.2 Overall program of works. Item Submission of the draft Public Environment Report to DEWHA Date July Consultation and assessment of PER July Submission of Development Application (to ACTPLA) July Detailed design June 2009 September ACT determination of DA August Commonwealth Minister for the Environment makes determination September Commence construction September Construction complete and commence filling December New reservoir at full supply level December (based on 2 6 years). As of July 2009 detailed design of the proposal is continuing and the final costs associated with the proposal are being determined as part of a target outturn cost by August ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

21 1 Introduction This chapter provides an overview of the Enlarged Cotter Dam proposal and introduction to the PER. 1.1 Overview The proposal will involve the creation of a larger reservoir by constructing a new dam wall approximately 125 metres (m) downstream of the existing Cotter Reservoir on the Cotter River in the Australian Capital Territory (ACT). The proposal will also involve two saddle dams on the right abutment (to the southern end of the main dam wall). The new dam will be approximately 80 m high and the adjacent saddle dams will be built to an approximate height of 12 m and 16 m. The full supply level of the reservoir will be approximately 550 m AHD (Australian Height Datum). The proposal will, once filled, increase the storage capacity from four gigalitres (GL) in the existing Cotter Reservoir to 78GL. The main dam will be constructed of roller compacted concrete (RCC) and the saddle dams will be constructed of earth/rock fill with a clay core. Figure 1.1 below provides a photomontage of the concept design of the proposal five (5) years post construction. Figure 1.1 Artist s impression of the proposal viewed from Moores Hill five (5) years post construction. The dam outlet works will incorporate provision for drawing water from multiple depths in the reservoir. The proposal will also require valving and pumping arrangements to allow for a variety of water extraction arrangements to respond to changing operational and environmental requirements. These modifications will enable: A blend of Cotter Reservoir and Murrumbidgee River water to be treated at Mount Stromlo Water Treatment Plant. 100 per cent of Cotter Reservoir water to be treated at Mount Stromlo Water Treatment Plant. 100 per cent of Murrumbidgee River water to be treated at Mount Stromlo Water Treatment Plant. 14 WATER SECURITY MAJOR PROJECTS AUGUST 2009

22 Murrumbidgee River water to be used for Cotter River environmental flow via recirculation pipe work. Cotter Reservoir water to be used for Cotter River environmental flow. The existing Cotter Reservoir is part of the ACT s water supply network and is required to remain in full operation throughout the construction period of the new dam. This will require the construction of a small temporary dam and temporary diversion culvert from the existing dam wall through the site of the new dam. The flood storage capacity of the existing dam will also be increased during the construction period by installing temporary barriers fixed to the crest of the existing dam wall and stilling basin end wall. The main construction site and quarry works will be located to the south-west of the proposed dam wall, on the right abutment. The quarry will supply the majority of aggregate for use in the production of concrete for the main dam and filters for the associated saddle dams. Other construction activities on site include crushing of rock, and stockpiling of aggregate materials, batching and delivery of RCC and conventional concrete to the dam and saddle dam sites, haulage and storage of materials required in construction processes (including sand, cement and concrete additives), construction of both temporary and permanent accesses and temporary fuel storage. The design of the main engineering infrastructure will be finalised as the detailed design of the proposal progresses. A summary of the scope of works is provided in Table 1.1. Table 1.1 Scope of works summary. Component Main dam Saddle dams Quarry Clay borrow areas Earthworks Haul/access roads Road intersection upgrades Rehabilitation works Electricity Supply Description A roller compacted concrete (RCC) dam, about 125 m downstream from the existing Cotter dam. The dam will be approximately 80 m high and will provide a full supply level (FSL) for the new reservoir of approximately 550 m AHD and associated engineering infrastructure including an intake tower, dam pipe work, stilling basin and abutment return channel Two (2) saddle dams will be located on the right hand side of the main dam wall. These will be approximately 12 and 16 m high with crest lengths of approximately 330 m. A rock quarry will be developed to extract local rock. The location of the quarry is southwest of the right abutment. Three (3) clay borrow areas (located predominantly under the FSL of the proposal) will be used to win onsite materials for construction of the main dam and saddle dams. Main construction areas for dam and saddle dams as well as construction set out pads. Permanent (including roads upgrades). Brindabella Road. Paddy s River Road. Native vegetation rehabilitation proposed on areas impacted upon by construction. Permanent electrical supply to proposal, including dam infrastructure and destratification units (mixers). ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

23 1.2 Context The proposal to enlarge the Cotter Reservoir is one (1) of a suite of new initiatives developed by ACTEW to secure the future water supply for the ACT and surrounding region. The proposal was announced by the ACT Government in October 2007, recognising the necessity to expand existing water supply infrastructure to withstand the effects of ongoing drought conditions and associated low inflows into ACT reservoirs. Figure 1.2 below provides the 2-year, 5-year and 10-year average total inflows into to Canberra s water supply system (Corin, Bendora and Googong Reservoirs) over the period of record (from 1871 to the present). Figure 1.2 Moving average inflows to Corin, Bendora and Googong Reservoirs. The past five (5) to ten (10) years represent the most severe long term dry period from 1871 to the present. Recent years exhibit inflows that are consistently lower than average, with remarkably similar low inflows from late Summer to early Winter. Using stochastic data, on average, a five (5) year period worse than the last five (5) years would occur once every 19 years. Therefore, the last few years would be a drought even with the impacts of predicted climate change. The Commonwealth Scientific and Industrial Research Organisation (CSIRO) Climate Change Report (2003) comments that there is evidence of a shift in the last 20 years, with several locations (Michelago is an exception) near to Canberra showing a small decline in rainfall and a decrease in inter-annual variability after the mid to late 1980s. A similar shift has been well documented in the southwest of Western Australia. The existing drought has resulted in the lowest inflows into the Canberra water supply catchments since The third lowest inflows of any year on record were produced in 2006, behind 1901 and However, the 1910s and 1940s also contained long term droughts where average inflow was only a little higher than experienced during the current period. It is noted, during 1950 to 1980 consistently high inflows were experienced, which have not been reproduced at other times. The inflows experienced since 1980, including the current drought conditions, appear similar to the period of record. 16 WATER SECURITY MAJOR PROJECTS AUGUST 2009

24 It cannot be definitively stated that the current south-eastern Australian dry period is influenced by climate change, rather than merely the result of natural climate variability. However, evidence suggests that climate change is affecting weather patterns around the globe. Although the recent drought experienced resembles previous recorded dry periods, this does not necessarily indicate that anthropogenic (human induced) climate change is not influencing current conditions. The lack of variability in recent climate also appears more pronounced than in earlier dry periods. 1.3 Objectives The ACT Government released its water resources strategy Think water, act water a strategy for sustainable water resources management (ACT Government, 2004a) on 28 April The strategy assigned ACTEW with the responsibility for assessing the reliability of the existing water supply and recommending options for new water sources for the ACT Government by March This strategy identified a series of objectives to guide sustainable management of water resources in the ACT, in particular, two (2) key objectives are to: Increase the efficiency of water usage. Provide a long term reliable source of water for the ACT and region. The Enlarged Cotter Dam is one (1) of the recommendations proposed by ACTEW and accepted by the ACT Government that is required to secure the ACT and region s future water supply. The overarching objective of the proposal is to increase the security of Canberra s water supply through increased storage capacity. 1.4 Scope and legislative basis of the PER In October 2008, ACTEW referred the proposal to the Commonwealth Department of Water Environment, Water, Heritage and the Arts (DEWHA) as required under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999). As required under the Act, ACTEW advised the Commonwealth the proposal has the potential to impact on matters of national environmental significance. ACTEW also advised DEWHA that it is progressing with ACT approvals under the Planning and Development Act 2007 which requires the preparation of an Environmental Impact Statement (EIS) for all development proposals that are to be assessed under the Impact Track. ACTEW included the draft EIS (prepared pursuant to Section 216(2) of the Planning and Development Act 2007) as part of the referral documentation. DEWHA determined on 12 November 2008 that under Sections 75 and 78 of the EPBC Act 1999 the construction of the proposal will be a controlled action (as per the Notice of Referral Decision and Designated Proponent Controlled Action Decision on Assessment Approach EPBC 2008/4524). The relevant controlling provision is based on the decision that it appears the proposal is likely to have a significant impact on listed threatened species and ecological communities (sections 18 and 18A of the EPBC Act 1999). DEWHA has requested that a PER be prepared to further assess the potential for significant impact on matters protected by the Australian Government under Chapter 4 of the EPBC Act 1999, specifically: The vulnerable Pink-tailed Worm Lizard (Aprasia parapulchella). The vulnerable Pale Pomaderris (Pomaderris pallida). The endangered Macquarie Perch (Macquaria australasica). The vulnerable Murray Cod (Maccullochella peelii peelii). The endangered Trout Cod (Maccullochella macquariensis). This PER has been prepared in accordance with the requirements of the EPBC Act 1999, EPBC Regulations 2000 (Schedule 4) and the written guidelines provided to ACTEW by DEWHA on 17 February ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

25 1.5 Studies, surveys and consultations to inform the proposal The studies, surveys and consultations undertaken to inform the proposal utilised rigorous and industry accepted methodologies and drew on relevant expert knowledge to ensure that the information gathered was focussed, current and reliable. All documentation was also independently peer reviewed for adequacy and content to ensure that the conclusions drawn by the specialist authors were acceptable Future Water Options In response to the ACT Government strategy Think water, act water, ACTEW launched the Future Water Options project on 30 April The project built on earlier work that had identified possible new water sources for the ACT and region as documented in the Options for the next ACT Water Source report (ACTEW, 2004a). Among more than 30 options, the report specifically highlighted and investigated three (3) main water sources for future supply to Canberra and the ACT. These options were: Building a new reservoir near Mt Tennent, south of Tharwa. Enlarging the existing Cotter Reservoir. Transferring water from Tantangara Reservoir in New South Wales (NSW) to the ACT. Studies were undertaken using a thorough, best practice approach to assess and evaluate environmental, social, economic and technical issues and preparation of preliminary engineering designs for the various alternatives Fish Impact Study The Fish Impact Study was undertaken by the Wildlife Research and Monitoring Unit of Environment ACT (now the ACT Environment Protection Authority (ACT EPA)) (ACT Government, 2005a) to assess the impacts of proposed future water supply options on fish and crayfish populations. The study assessed the impact of proposal on six (6) threatened fish or crayfish species (listed under Commonwealth, NSW and ACT legislation) in the Upper Murrumbidgee catchment. These species include: The Macquarie Perch (Macquaria australasica). The Trout Cod (Maccullochella macquariensis). The Murray Cod (Maccullochella peelii peelii). The Two-spined Blackfish (Gadopsis bispinosus). The Silver Perch (Bidyanus bidyanus). The Murray River Crayfish (Euastacus armatus). The study identified issues surrounding the impact of the proposal, which have been identified and are currently being quantified, with mitigation measures being refined through further investigation. These issues have been further assessed in the subsequent ECD Fish Management Plan (discussed in Section below) with the mitigation measures and environmental management strategies detailed in the study incorporated into construction and operational commitments for the proposal Aquatic Ecology Study The Aquatic Ecology Study (Future Water Options) was undertaken by the Water Research Centre, University of Canberra (2005). The aim of the study was to establish whether there is a major constraint or impediment to implementation of any of the proposed future water supply options because of significant aquatic biodiversity issues (excluding fish) and complement the work on fish which was undertaken simultaneously in the Fish Impact Study (ACT Government, 2005a). This report provides a description of the existing aquatic habitat and associated biological assemblages that may be affected by each of the options, directly or indirectly including; possible future inundation areas, and areas within and adjacent to any pipeline 18 WATER SECURITY MAJOR PROJECTS AUGUST 2009

26 or channel corridors downstream of proposed storages. The study also identifies potential effects or constraints arising from the following: Vulnerable, threatened or endangered species. Sites and extent of any significant wetlands in the catchments that may be impacted by the options. Any wetlands or aquatic places listed or interim listed on the register of the National Estate that may be affected by the options. Effects of potential alterations to water quality and flow regimes on aquatic flora and fauna. Fragmentation. The environmental management strategies detailed in the study have been incorporated into construction and operational commitments for the proposal ECD Fish Management Plan The ECD Fish Management Plan (ActewAGL, 2009a) was prepared by ActewAGL, on behalf of ACTEW, to provide information on how threatened fish species will be protected during the construction filling and operational phases of the proposal. The information presented is intended to assist in obtaining the relevant licences and approvals in accordance with Commonwealth and ACT legislation. The overarching objective of the ECD Fish Management Plan is to ensure that the aquatic communities and habitats of the lower Cotter River are maintained or rehabilitated to support native fish and crayfish species. The Plan has been rigorously peer reviewed and was informed through extensive stakeholder involvement. The Plan makes full use of existing relevant environmental information, but also identifies and addresses knowledge gaps to ensure all management strategies are appropriate Constructed homes for threatened fishes in the Cotter River catchment: Phase 1 Report This is one (1) of a suite of projects to address identified threats and is designed to investigate whether threatened fish species will utilise constructed artificial habitats in water supply reservoirs. This phase has involved the construction of habitats, which took place over a nine (9) month period in This phase has been successfully completed in September 2008 by the University of Canberra and has achieved the following outcomes: A literature review related to habitat for threatened fishes, habitat enhancement in water supply reservoirs, cost-effective materials for artificial habitats that are reservoir-safe, and appropriate techniques for assessment of habitat use. The review revealed a range of natural and artificial materials are used in creating or restoring fish habitat. It also highlighted the need for an adaptive management approach. A conceptual project design (including peer review). The selection of experimental sites within the Cotter reservoir. The recruitment of personnel. The purchase of the required equipment. A pilot study of reef construction techniques and application of telemetry equipment and methods. The collection of adult fish and surgical implantation of radio tags. An assessment of fish presence at intervention sites before reef construction, using radio-tagging methods and underwater video recording. The study design has been externally reviewed and endorsed by appropriately qualified experts, with the pilot study demonstrating the efficacy and reliability of the study design and methods. Phase 1 has also explored the potential for providing artificial spawning habitats for Macquarie Perch (and the ACT listed Twospined Blackfish) in the Cotter catchment and developed a conceptual design for possible investigation of ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

27 habitat use by these species, with a view to trialling the enhancement of spawning habitat in Phase 2 (Refer Appendix B2) Constructed homes for threatened fishes in the Cotter River catchment: Phase 2 Report Phase 2 of the project, from early 2009 to August 2010, builds on Phase 1 to deliver high quality research outputs and management advice essential to the threatened fishes in the Cotter catchment. The primary focus is on the Macquarie Perch, whose only remaining viable population in the ACT is within the Cotter Reservoir. Phase 2 has the following aims: Determine whether adult Macquarie Perch will use artificial habitat for shelter when emergent macrophytes are not available. Provide guidelines for construction of long term habitat to sustain threatened fishes during the construction and operation of the proposal. Preliminary findings and advice on the design and construction of artificial habitats for use by Macquarie Perch in the Cotter Reservoir will be provided by the end of August The final project outputs are scheduled for completion by August Terrestrial biodiversity assessment A terrestrial flora and fauna assessment was prepared as part of the EIS by Biosis Research Pty Ltd (Biosis, 2009a) to evaluate the potential impact of enlarging the Cotter Reservoir. The evaluation was based upon flora and fauna surveys across the study area between December 2007 and May 2008, which involved extensive survey transects for plants, vegetation mapping, trapping, detection and observations for grounddwelling, arboreal and flying mammals, bird observations, active searches for reptiles and amphibians and spotlighting for nocturnal fauna. The aims of the study were: To describe the vegetation and habitats of the study area. To determine the likely presence of rare and threatened species of plant and animal. To consider the extent of impact of the proposed development and make recommendations to mitigate impacts. The report proposes a number of recommendations aimed at ensuring the long term viability of native terrestrial flora and fauna Land status report This report was prepared by KMR Consulting (2008) to examine the current land ownership, management and land use in the areas potentially affected by the proposal as part of the EIS process. Areas examined include: The proposal area. The Cotter catchment area surrounding the proposal. The western end of the access route for construction traffic. The information for this report was collected from publicly available sources including the Land Titles Office, the Territory Plan, publications and plans produced by TAMS. Discussions were held with officers of the ACT Government and the Commonwealth Government for the purposes of identifying interests in land, sources of information, clarifying information and confirmation that sources used provided the most up-to-date information available. 20 WATER SECURITY MAJOR PROJECTS AUGUST 2009

28 1.5.9 Community consultation on the draft Environmental Impact Statement This report, prepared by ACTEW (2009b), details the stakeholder and community engagement activities undertaken during the consultation on the draft EIS for the proposal and identifies the outcomes. This program complemented the ACT Planning and Land Authority s (ACTPLA) formal public notification of the draft EIS. The report and EIS community consultation program builds on a long term commitment by ACTEW to involve the broader community and key stakeholders in the planning for future water supply options for Canberra. The Cotter Reservoir holds particular significance in the Canberra community as a well-loved recreation area and it is important that their opinions and feedback continues to be an integral part of proposals investigations and developments The Cotter Dam Option This report, prepared by ACTEW (2005a) specifically on the Cotter Reservoir, is part of a suite analysing the future water options for the ACT, identified as part of the ACT Government s Think water, act water strategy and assesses the various alternatives for the future use of the Cotter Reservoir. It illustrates a logical increase in the utilisation of the Cotter catchment, based on its history as Canberra s main water supply since the time of Canberra s settlement, its designation as such in the relevant planning documents and legislation, and a high and reliable rainfall record Enlarged Cotter Dam update report This report was prepared by ACTEW (2007b) was developed as part of the Water Security Program to provide comment on investigations and other work carried out on developing the Cotter Dam Option between 2005 and 2007 and to draw attention to any changes which might have occurred over this period. This report provides an update to The Cotter Dam Option report (ACTEW, 2005a), informs EIS investigations and supports the progression of the proposal Enlarged Cotter Dam Terrestrial Species Report Pomaderris pallida and Aprasia parapulchella This report (Appendix B1) has been prepared by Biosis Research Pty Ltd (2009b) and documents the terrestrial flora and fauna impact assessment undertaken as part of the PER to evaluate the potential impact of increasing the capacity of the existing Cotter Reservoir from four GL to 78GL. The evaluation was based upon extensive flora and fauna surveys across the study area between December 2007 and May The report describes: Two (2) nationally vulnerable species Pomaderris pallida (Pale Pomaderris) and Aprasia parapulchella (Pink-tailed Worm Lizard). The potential impacts from the proposal on these species. The assessment (Appendix B of the Biosis report) of those potential impacts against the EPBC Act Policy Statement 1.1 Significant Impact Criteria (Department of the Environment, Water, Heritage and the Arts, 2006), concluding there will be no significant impact these species. The report also describes the establishment of approximately 400ha of native vegetation as direct compensation for the loss of native and non-native vegetation caused by the construction activities and increased inundation of the reservoir. However, this was not proposed as an offset due to impacts on the potential habitat for these terrestrial species. Prior to inclusion in the PER, this report was peer reviewed by two (2) independent experts to verify the accuracy and completeness of the information presented. The qualifications and experience of these expert peer reviewers are presented in Appendix C. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

29 1.6 Summary of priority environmental and management issues The Guidelines for a Public Environment Report Cotter Dam Expansion, Paddy s River Road, ACT have identified several priority environmental and management issues relating to matters of national environmental significance, namely listed threatened species and ecological communities (terrestrial and aquatic biodiversity) Terrestrial biodiversity The area impacted by the proposal provides habitat types that range from very poor to good condition. Areas previously used intensively for pine plantations and settlements generally have poor habitat attributes and low native species diversity. In contrast, relatively intact riparian communities, dry woodlands and open rocky outcrops and gully slopes (within the Cotter River gorge) provide important habitat opportunities for a more diverse range of flora and fauna, including some rare and threatened species. Some of these areas have high conservation value as potential habitat and are part of local and regional wildlife movement corridors. The presence of two (2) nationally listed threatened species Pomaderris pallida and Aprasia parapulchella were investigated, although no individuals of either species were recorded in the vicinity of the proposal (Biosis, 2009b). Both species have a wide, though scattered, distribution along the Murrumbidgee River and Molonglo River corridors and are recorded within one kilometre of the study area. Although there was no substantive evidence of either species occurring within the dam construction footprint, the restricted access to some sections of the southern slope, and total exclusion from the northern slope (though neither species is commonly recorded on slopes with southerly aspects) was a limitation in establishing the presence or absence of these species. Importantly, the combination of rocky habitat, native vegetation cover and a northerly aspect suggests the presence of suitable habitat for these species Aquatic biodiversity Enlarging the reservoir will result in disturbance of aquatic biodiversity during construction, loss of upstream habitat due to inundation and hydrological disturbance to the lower Cotter River. A larger reservoir will have proportionally larger impacts on the Murrumbidgee River and upstream habitat. The construction of a reservoir does, however, provide for the controlled release of water to mimic natural flows or maximise ecological benefits at critical times. A key determinant of the impact on downstream aquatic biodiversity is the design and operation of the reservoir allowing for an appropriate environmental flow regime. Three (3) fish species; Macquarie Perch, Trout Cod and Murray Cod, listed as endangered and vulnerable, could potentially be affected by the proposal. Macquarie Perch The main potential impacts of the proposal on Macquarie Perch have been identified by Lintermans (2005) and the ACT Government (2007a) as: Loss of preferred habitat and protective cover due to inundation of macrophyte reed beds. Disruption of breeding cycles by the inundation and destruction of critical spawning habitat in the Cotter River immediately upstream of the Cotter Reservoir. There is also a risk that the storage level of the enlarged reservoir may coincide with an area containing minor barriers to fish movement that will prevent spawning migrations at critical times of the year. The preferred habitat of the Macquarie Perch is cool, shaded, upland streams with deep rocky pools and substantial cover. However, they survive well in impoundments such as the Cotter Reservoir provided that there is access to spawning habitat, which in this case is the Cotter River, upstream of Cotter Reservoir. An expansion in alien fish species populations due to the larger reservoir, which may lead to increased predation by species such as trout, or increased competition from species, such as the Eastern Gambusia (Gambusia holbrooki ) and Oriental Weatherloach (Misgurnus anguillicaudatus). 22 WATER SECURITY MAJOR PROJECTS AUGUST 2009

30 An increase in the number of cormorants in the larger reservoir cormorants are known to prey on Macquarie Perch during spawning migrations into the Cotter River. An increased risk of introducing the fish epizootic haematopoietic necrosis (EHN) virus into the Cotter Reservoir as a result of design, construction and operation of the proposal. Murray Cod Murray Cod are located in the Murrumbidgee River downstream of the existing reservoir and the Cotter River. They are a valuable recreational fishing species and are not considered threatened in the ACT. The likely key impacts to the Murray Cod population in the Murrumbidgee River include the following: Potential changes to suitable conditions for spawning habitat due to potential downstream flow alterations. Potential changes to recruitment and spawning ability due to potential downstream flow alterations. Trout Cod Trout Cod are located only in the Bendora Reservoir in the ACT and therefore the impact of the proposal on this species would be minimal. However, it is likely that at least some individuals have been displaced downstream into the Cotter River between Bendora and Cotter reservoirs and that the species will colonise or be stocked into Cotter Reservoir. Apart from the risks to these species, the proposal may also produce some potential benefits for these species and include: A substantially larger body of water (and thus potential habitat) for these four (4) threatened species. This may also provide additional food resources, refuge areas from predators and an enhanced thermal refuge from high summer water temperatures. Enhanced boulder habitat which could be provided as a result of the construction activity resulting from the enlargement process. Potential reduction in some existing movement barriers that currently limit upstream movement of native species (due to the flooding of such barriers by the enlarged reservoir). Enhanced stream habitat which could be provided as a result of the construction activity resulting from the enlargement process. This would involve reducing the armouring of stream beds. Greater flexibility with large environmental flow releases from Bendora Reservoir (as the water could still be captured and used by the proposal). Each of these priority issues are detailed and assessed in Chapters 7 and 8 for terrestrial and aquatic ecology, respectively. 1.7 Responsibilities for preparing the PER This PER has been prepared by ACTEW Corporation Limited (ACTEW). A number of personnel were involved in the preparation and peer review of the report. A list detailing each person, their qualifications and involvement is provided in Appendix C. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

31 1.8 Structure of the PER The PER has been structured to correspond with the requirements of the Guidelines for a Public Environment Report Cotter Dam Expansion, Paddy s River Road, ACT and the EPBC Regulations (Schedule 4), Table 1.2 PER structure. Chapter Outline ES Executive summary 1 Introduction A description of the components, objectives and context of the proposal, the scope and requirements of the PER, studies that have been undertaken and priority environmental and management issues. 2 Background A description of the background to the proposal including current and future capacity and uses of the Cotter Reservoir, the current status of the proposal and schemes, plans or policies relevant to the proposal. 3 Location and tenure A description of the size and location of the proposal area, in particular the location and boundaries of land tenures and areas of conservation value which may be impacted by the proposal. 4 Proposal justification and need Addresses the specific objectives and justification of the proposal in terms of the principles of ecologically sustainable development, as defined by the EBPC Act Options and alternatives An analysis of the feasible alternatives to the enlargement of the Cotter Reservoir, the environmental and socio-economic impacts of each alternative, including not proceeding with the proposal and a discussion of why the proposal is a preferred option. 6 Description of the proposal A description of the design, construction and operation of the proposal as relevant to the assessment of impacts on listed threatened species, ecological communities and the local environment. 7 Environmental values and management of impacts: Terrestrial A detailed description of relevant environmental values, potential impacts, environmental objectives, monitoring programs and management strategies for listed terrestrial species in the vicinity of the proposal. 8 Environmental values and management of impacts: Aquatic A detailed description of relevant environmental values, potential impacts, environmental objectives, monitoring programs and management strategies for listed aquatic species in the vicinity of the proposal. 9 Community consultation A description of the ongoing community consultation program and community sentiments regarding the proposal. 24 WATER SECURITY MAJOR PROJECTS AUGUST 2009

32 Chapter Outline 10 Conclusion A concluding statement of impacts on listed threatened species and recommendations to avoid adverse consequences. 11 References A listing of the information sources used to prepare the PER. 12 Glossary and abbreviations Terms and definitions provided to assist the reader in understanding the technical content of the PER. 13 Appendices Supplementary information provided to support the PER. 13 A PER Guidelines cross reference table A table showing where the issues identified in the Guidelines for a Public Environment Report Cotter Dam Expansion, Paddy s River Road, ACT can be referenced in the PER. 13 B Studies Specialist Terrestrial Species Report Study undertaken by independent experts to assess the potential impacts of the proposals on listed threatened terrestrial species. Progress Report on Project 1 Study undertaken to assess the current success of Project 1 Artificial fish habitats. 13 C Study team Details the expertise of the individuals involved in the preparation of the PER. 13 D Environmental record of the person proposing the action Details the proponents environmental record and policy. 13 E ACTEW Corporation Limited referral documentation A copy of the referral documentation provided to DEWHA. 13 F Detailed legislation Further detailed descriptions of the legislation relevant to the proposal. 13 G Consultation A summary of the meetings and presentations with government authorities and stakeholder groups in the development of the draft EIS. 13 H PER guidelines A copy of the covering letter and PER guidelines submitted to ACTEW from DEWHA. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

33 2 Background This chapter discusses the background to the proposal, current and future capacity and uses of the Cotter Reservoir and current status of the proposal, including relevant planning instruments. 2.1 Background to the proposal The enlargement of the Cotter Reservoir is required to secure reliable water supply and meet the future demand for water due to the continual growth of the ACT. The need for a reliable water supply has been reinforced due to the effects of predicted climate change. The proposal is one (1) of the preferred options for delivering improved security to Canberra s water supply. The ACT Government in a press release announced the proposal in October 2007 (the ACT Government decision and announcement of the key initiatives for securing Canberra s Water Supply) as one (1) of a suite of initiatives to secure the ACT s water supply. The selection of major infrastructure initiatives was based on more than four (4) years of investigations undertaken by ACTEW, ActewAGL and the ACT Government to identify sustainable future water sources for Canberra and the region. These investigations included: The ACT Government s Think water, act water a strategy for sustainable water resources management (2004a). ACTEW s Future Water Options project 2004/2005 (2005b). ACTEW s Review of Future Water Options Assumptions (2006). ActewAGL s Review of Future Water Option (2007a). ACTEW s Recommendations to the ACT Government regarding the Security of the ACT s water supply (2007a). Each of the above studies are detailed in Section 1.5 and are the basis for the ACT Government s water plan announced on 23 October 2007, in the media release Enlarged Cotter Dam, Murrumbidgee Extraction and Pilot Purification Plant: Highlights of Water Plan (ACT Government, 2007h). 2.2 The future of the Cotter Reservoir The proposal will increase the capacity of the Cotter Reservoir from four GL to approximately 78GL increasing the ACT s overall storage capacity by one third. Once constructed, the workforce, catchment management and other key operating parameters for the proposal will be similar to the operation of the existing reservoir. Notably, with the exception of the inundation area, management requirements of the catchment will not change. The proposal will play a significant role in Canberra s water supply system. Where the existing reservoir has, until recently, rarely been used, the new reservoir will be actively operated as a water supply reservoir. In this role it will be regularly and intentionally drawn down to ensure the capacity to capture high flow events and supply water to Canberra. Therefore, the key differences in operation between the existing and future Cotter reservoirs will be: The more frequent extraction of water (and hence increased variability in water levels). The improved ability to manage the quality of the water drawn or released from the reservoir. The improved ability to capture environmental flow releases from upstream dams. 26 WATER SECURITY MAJOR PROJECTS AUGUST 2009

34 2.3 Relevant statutory and planning instruments and important government guidelines Commonwealth legislation There are a number of Commonwealth statutes in relation to this proposal and include: EPBC Act 1999 (this is not detailed). Australian Capital Territory (Planning and Land Management) Act Water Act Native Title Act Australian Capital Territory (Planning and Land Management) Act 1998 The Australian Capital Territory (Planning and Land Management) Act 1988 establishes the National Capital Authority (NCA) as the Commonwealth government authority with responsibility to prepare and administer a National Capital Plan, with the intention of representing the Commonwealth interest in the Territory. The important planning instruments are: National Capital Plan. National Capital Open Space System (NCOSS). River corridor land. Mountains and bushland. These instruments are further described in Appendix F. The proposal to enlarge the Cotter Reservoir has been developed to be consistent with the policies of the National Capital Plan (ACT Government, 2002a). The proponent has had direct discussions with the NCA regarding this proposal and their support was reinforced by their letter received during the notification period of the draft EIS (personal communication, 30 January 2008). Water Act 2007 On 3 March 2008 the Commonwealth s Water Act 2007 came into effect. This legislation was enacted to make provision for the management of water resources in the Murray-Darling Basin. More detail is provided in Appendix F. Given that the proposal and its associated activities are primarily related to augmenting water storage capacity for the ACT, they are not likely to impact upon the objects of the Act or Basin Plan, or contradict terms of the intergovernmental Agreement on Murray-Darling Basin Reform (Department of Environment, Water, Heritage and the Arts, 2008c). It can therefore be concluded that the implications of the Water Act 2007 for the proposal are relatively limited (compared to the other legislation described above). The concurrence of the Murray-Darling Basin Authority may be required in terms of establishing additional storage capacity in the Cotter Reservoir. Under the agreement the ACT adheres to a Water Abstraction Cap of 42 GL per year net. This amount will not change as a result of either the construction or operation of the proposal (Department of Environment, Water, Heritage and the Arts, 2008c). Native Title Act 1993 The Commonwealth Native Title Act 1993 was developed to provide for the recognition and protection of native title for those people whose descendants are now known as Aboriginal peoples and Torres Strait Islanders who inhabited Australia before European settlement. The main objectives of the Act is to provide for the recognition and protection of native title, establish a pathway for future native title dealings, provide a mechanism for native title claims and to provide for, or permit, the validation of past acts, and intermediate period acts, invalidated because of the existence of native title. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

35 Given that all lands within the proposal area are either owned by the ACT Government or leased from the ACT Government by ACTEW, the Native Title Act 1993 has no bearing on the proposal Territory (ACT) legislation All development proposals within the ACT are required to have regard to and comply where applicable to the total statute of the ACT (all legislation with associated sub-laws, regulations, notifiable and disallowable instruments). Legislation of relevance to the proposal include: Planning and Development Act Heritage Act Environment Protection Act Nature Conservation Act 1980 (NC Act 1980). Water Resources Act Utilities Act Water and Sewerage Act Fisheries Act Occupational Health and Safety Act Work Safety Act Discussion on the applicability of the ACT Planning and Development Act 2007 is provided below. The remainder of the above listed statutes and their applicability are provided in Appendix F. Planning and Development Act 2007 The Commonwealth, through the Australian Capital Territory (Planning and Land Management) Act 1998, requires that the ACT Legislative Assembly make laws to establish a territory planning authority. The role of the authority is to prepare and administer a plan in respect of all land within the ACT other than designated areas, in a manner not inconsistent with the National Capital Plan. In accordance with the Act, ACTPLA administers the Territory Plan. This is the primary statutory planning document against which development proposals are assessed. The Territory Plan identifies land zoning in all areas of the territory. The nature of the approval process depends on the nature of the proposal and the zoning of the land that the proposal will affect. A development application (DA) made under the Act is assessed in one (1) of three (3) tracks of increasing complexity reflecting the nature of the proposal. The three (3) tracks are code, merit and impact. Under the Planning and Development Act 2007, any proposal assessed under the impact track requires the preparation of an EIS. As stipulated in Schedule 4 of the Act, an EIS has been prepared by ACTEW to assess the relevant environmental impacts of the proposed dam as it is at least ten metres high. The EIS has been prepared in accordance with the Scoping Document provided by ACTPLA to assess the significance of environmental impacts relevant to the ACT. To inform the preparation of the EIS a range of specialist studies, reports and consultations were undertaken. ACTEW submitted a draft EIS to ACTPLA that was publicly notified in October A total of 16 public and agency comments were received. As required by the Act, ACTEW revised the draft EIS taking all received comments into consideration and submitted the final EIS to ACTPLA on 17 February ACTPLA s consideration of the final EIS resulted in a Section 224 Notice, a request for further information, being prepared. The Section 224 Notice was lodged on 8 May The final EIS was approved by the ACT Planning Minister on 19 June 2009 and a DA (as described in Section 123 of the Act) has been submitted to ACTPLA for approval. 28 WATER SECURITY MAJOR PROJECTS AUGUST 2009

36 The DA will be assessed as per the requirements described in Divisions 7.2 and 7.3 of the Act and involve consideration against the supplementary Acts (as per the list above) Other important Commonwealth and Territory policies In developing the proposal ACTEW has also drawn on the guidance, recommendations and requirements of Commonwealth and ACT Government policies. These include: Water availability in the Murray Darling Basin Sustainable Yields Project. ACT Management of public land. Weathering the Change The ACT Climate Change Strategy Draft Lower Cotter Catchment Recreation Strategy Draft ACT Heritage Guidelines Sustainable Community Attitudes Study. ACT Environmental Flow Guidelines Bush Capital Legacy iconic city, iconic natural assets. Integrated Nature Conservation Plan. Southwest ACT Rural Sub-catchment Plan These policies and their applicability to the proposal are discussed in Appendix F Outcomes In the research undertaken to inform the proposal, the issues raised by above legislation, plans and policies were investigated. The proposal aims to create no significant adverse impacts and maintain future sustainability of all affected catchments. Impacts and mitigation measures are detailed in Chapter 7 for terrestrial ecology and Chapter 8 for aquatic ecology All approvals required Table 2.1 provides a list of the approvals required for the proposal. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

37 30 AUGUST 2009 WATER SECURITY MAJOR PROJECTS Table 2.1 List of the approvals required for the proposal. Approval Legislation Authority Required documentation Timing Status EPBC approval for a controlled action. EIS and DA. Land and easement acquisition (proposed establishement of Crown leases and service easements over infrastructure). Cotter Road, Haul Road, Early works DA's. Exemption for licence to take water (for construction). Licence to take water (operations). Commonwealth EPBC Act ACT Planning and Development Act ACT Planning and Development Act ACT Planning and Development Act DEWHA. Minister for Environment. ACTPLA. Minister for Planning. ACTPLA, TAMS PCL. Public Environmental Report. Request for Scoping document. Draft EIS. Final EIS. Response to 224 Notice. DA. Land and easement acquisition processes (if required). Pre-construction. This report. Pre-construction. Final EIS submitted 17 February Response to Section 224 Notice submitted 8 May Final EIS approved 19 June DA submitted June Pre-construction. ACTEW is investigating land occupancy licence. ACTPLA. DA matters. Pre-construction. DA submitted June ACT Water Resource Act TAMS, ACT EPA. Letter for exemption/application to take water. Pre-construction. ACT Water Resource Act TAMS, ACT EPA. Licence application. Postconstruction. Heritage approvals. ACT Heritage Act ACT Heritage Council. Conservation (heritage) Management Plan. Licence to salvage. Waterway works licence. ACT Water Resource Act TAMS, ACT EPA. Waterway works licence application. Pre-construction. Pre-construction. Approval will be sought in parallel with DA assessment (2009). Approval will be sought at the end of the construction phase. Approval will be sought in parallel with DA assessment (2009). Approval will be sought in parallel with DA assessment (2009).

38 Approval Legislation Authority Required documentation Timing Status Environmental authorisation (Extraction of material (not water) from a waterway). ACT Environment Protection Act TAMS, ACT EPA. Environmental authorisation application. Pre-construction. Approval will be sought in parallel with DA assessment (2009). Clearing of native wegetation. CEMP approval. Endorsement of Dam Safety. ACT NC Act 1980 EPA. Application with supporting documentation ACT Environment Protection Act TAMS, ACT EPA. CEMP with associated management sub-plans. Pre-construction. Pre-construction. Approval will be sought in parallel with DA assessment (2009). Approval will be sought in parallel with DA assessment (2009). ACT Utilities Act ACTPLA. Statement of compliance Pre-construction Submitted as condition of DA. ENLARGEMENT OF THE COTTER RESERVO R AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

39 2.4 Monitoring enforcement and review procedures Environmental Management System An Environmental Management System (EMS) has been prepared in accordance with the Australian/New Zealand Standard ISO 14001:2004 (Environmental Management System) requirements to provide an overarching framework for identifying environmental issues, monitoring environmental performance and reporting outcomes during the delivery of the proposal. The key component is the Environmental Policy developed to provide the overall objectives for environmental management of issues for the proposal. The EMS has also been developed to meet the requirements of the ActewAGL Environmental Management Plan ( ) and policy statement. The EMS comprises of a Construction Environmental Management Plan (CEMP) and an Operation Environmental Management Plan (OEMP) and a series of management sub plans specific to environmental elements associated with the construction and operation activities. Each plan will provide the monitoring, enforcement and review procedures for all environmental issues during construction and operation activities. Monitoring will be undertaken through regular inspections and auditing to evaluate performance. Enforcement (or compliance) with the objectives of the overarching EMS and CEMP/OEMP s will be conducted and documented through the corrective action (and non-conformance) procedure (and in accordance with quality assurance provisions). Management review will be provided annually to evaluate performance and ensure system objectives are continually met. These provisions will allow for continuous improvement of operations during the delivery of the proposal. Further details of the CEMP, management framework and OEMP are provided in the following sections. Figure 2.1 provides a diagrammatic representation of the environmental management system for the delivery of the proposal. 32 WATER SECURITY MAJOR PROJECTS AUGUST 2009

40 Figure 2.1 Framework environmental management system. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

41 2.4.2 Construction Environmental Management Plan The key performance objective set by the BWA is to ensure compliance with all environmental legislation and approvals, including minimising pollution, waste generation and minimising environmental impacts during the construction of the proposal. The purpose of the CEMP is to provide an easily interpreted reference document that ensures all the proposals environmental commitments, safe guards and mitigation measures from the: Bulk Water Alliance Environmental Management System. Environmental planning and approvals. Project Alliance Agreement. These commitments, safe guards and mitigation measures are will be implemented, monitored, audited/reviewed and improved during the course of construction activities. In addition, the purpose of the CEMP is also to document the risk identification and management process for the construction techniques to be adopted by the BWA, and to document the systematic process of implementing controls to minimise the impacts of construction activities on the environment. The CEMP provides a workable document for construction crews to ensure that construction activities occur in a manner which minimises any potential negative impacts on both the natural environment and ACT s potable water supply. It uses formalised procedures, site surveillance, training and checklists to ensure protection measures are in place. The CEMP operates under the principles of an EMS with formalised nonconformance management and documented closure of identified corrective actions. This CEMP, management sub-plans and Construction Method Statements (CMS) are detailed in the following sections. The following objectives and associated key performance targets (where applicable) will also be adopted as part of the implementation of the CEMP as detailed in Table 2.2. Table 2.2 Objectives and targets. No. Objectives Targets 1 To employ best management practices to ensure that the construction proposal meets environmental legislative requirements. 2 To employ best environmental management practice to ensure compliance with all planning approvals. 3 To employ best management practice to minimise noise and vibration impacts. 4 Apply best management practices to soil and water quality management onsite. 5 To minimise air pollution from construction activities. No breaches of ACT or Commonwealth environmental legislative requirements. No non-compliance with planning approvals. Maintain noise and vibration impacts within the criteria detailed in the Noise and vibration management plan. Meet best practice water quality criteria for all water leaving construction areas during dry weather conditions and designed storm events to avoid water quality impacts. Meet air quality goals referred to in the Air Quality Management Plan. 34 WATER SECURITY MAJOR PROJECTS AUGUST 2009

42 No. Objectives Targets 6 To minimise impacts to the environment caused by the management of contaminated soil. 7 To protect vegetation and fauna within and adjacent to construction activities. 8 To avoid pollution of the environment caused by spills or leaks onsite. 9 To minimise waste resulting from proposal activities. Manage contaminated soils in accordance with Environmental legislative requirements and ACT EPA guidelines. No disturbance or damage to vegetation communities outside the construction corridor. No harm to threatened or protected flora and fauna. No major spills onsite. 100 % recycling of recyclable materials or re-use onsite Management sub-plans The management sub-plans document the aspects, impacts, safeguards and monitoring requirements for each key environmental element, and also nominate who is responsible for implementing those controls and the frequency/timing of implementation. These sub-plans also include checklists of obligations and safeguards in relation to each element. The sub-plans follow prescriptive content requirements of the BWA, ACT and Commonwealth legislative requirements. These sub plans will include: Terrestrial flora and fauna management plan. Aquatic flora and fauna management plan. Soil and water quality management plan. Noise and vibration management plan. Air quality management plan. Waste avoidance and resource recovery management plan. Environmental emergency response management plan (including bushfire and flood). Landscape rehabilitation management plan. Quarry management plan. Carbon (sustainability) management plan. Drilling and blasting management plan. Lighting management plan. Batch plant management plan. Conservation (heritage) management plan. Traffic and public safety management plan. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

43 2.4.4 Construction Method Statements CMS are documents detailing proposed work procedures and specific environmental control measures for activities which require more detailed attention and are developed at the planning phase prior to activities occurring on site. Once approved, they provide a step by step assessment of work activities and appropriate mitigation measures to minimise potential environmental impacts. CMS are developed by the construction site engineer in consultation with the superintendent and site environmental representatives. Each will include: Title, date and revision number. Summary of proposed activities. Location of the activity/site. Timing of works and expected duration. Details of any approvals/permits required. Step-by-step description of work activities. Assessment of the predicted level of environmental risk and community concern. Detailed consultation requirements. Environmental elements identified by the BWA from their environmental due diligence investigations. Implementation details such as: Measures to avoid and/or minimise negative environmental impacts. The methods proposed to implement the CMS, such as plans, schedules and work instructions. Site specific monitoring, inspection and test plans Operation Environmental Management Plan The OEMP provides a framework for the management of specific environmental issues during the operational stage of the proposal and incorporates specific ongoing monitoring and reporting requirements. Requirements are based on the same documents, approvals and agreements as those for the CEMP. Monitoring and reporting conducted during filling and operations will be measured against the objectives detailed in the OEMP and the requirements of all governing statutes (e.g. licence, permits), standards and guidelines (e.g. Australian Standards, National Association of Testing Authorities (NATA)). 2.5 Relation of the proposal to other actions Several actions are being undertaken in the vicinity of the proposal site (surrounding the Cotter River catchment) and include: The revegetation of the Lower Cotter catchment currently being undertaken by the ACT Government and ACTEW. The augmentation of the Cotter Pumping Station project to be undertaken by ACTEW through the BWA. The Murrumbidgee to Googong water transfer project to be undertaken by ACTEW through the BWA. The Moores Hill viewing platform to be undertaken by ACTEW. The Casuarina Sands upgrade to be undertaken by ACTEW. The implementation of various projects as part of the ECD Fish Management Plan currently being undertaken by ACTEW through the BWA. 36 WATER SECURITY MAJOR PROJECTS AUGUST 2009

44 Each of the above are being undertaken independently of the proposal, are not within the proposal site and are not expected to have a cumulative impact on the proposal or on matters of national environmental significance. Further details on each action are provided as follows Revegetation of the Lower Cotter catchment The revegetation of the Lower Cotter catchment is being undertaken to remediate areas following the 2003 bushfires. Since 2005, extensive rehabilitation works have been undertaken, with over 1000ha revegetated in a joint project between the ACT Government and ACTEW. The project had the dual role of remediation of areas damaged by the 2003 bushfires, and also involved catchment remediation to improve the water quality in the existing Cotter Reservoir. The work also provided for a possible future enlargement of the reservoir. This work is being undertaken independently of the proposal, but will complement the restoration activities that will be undertaken following construction. It is expected that these works will have a beneficial impact on listed terrestrial and aquatic species in the vicinity of the proposal through the provision of potential habitat and improved water quality in the reservoir and Cotter River Augmentation of the Cotter Pumping Station Works are currently being undertaken by ACTEW to augment the existing pumps at the Cotter Pumping Station. This project is being undertaken independently of the proposal and is not expected to have any impact of matters of NES or impact on Commonwealth land. ACTEW does not intend to refer this action to DEWHA Murrumbidgee to Googong water transfer The Murrumbidgee to Googong water transfer proposal, currently under development by ACTEW, would involve the abstraction of water from the Murrumbidgee River south of the ACT, and transfer to the Googong Reservoir for storage. This proposal has the potential to impact matters of national environmental significance, notably the Murray Cod, which may be present in the Murrumbidgee River in the vicinity of works. The proposal has the potential to impact listed threatened species, it will be referred to DEWHA for consideration under the EPBC Act Moores Hill viewing platform A viewing platform will be constructed on Moores Hill, adjacent to the proposed site, to allow safe visitation and viewing of the Cotter Reservoir during and after construction. The platform will provide an opportunity for the community to interact with the reservoir and will form an integral part of the community engagement and education program. Preliminary designs are currently being prepared and will take into account any areas identified as potential habitat for listed threatened terrestrial species. It is unlikely that this proposal will affect any matters of NES or impact on Commonwealth land, therefore, ACTEW does not intend to refer this action to DEWHA Casuarina Sands upgrade This project proposes the upgrade of the existing picnic facilities at Casuarina Sands, a recreational area located in the Cotter Precinct. These works will provide a positive legacy for the community. No works are proposed within riparian habitat or the Cotter River making it unlikely that this proposal will affect any matters of NES or impact on Commonwealth land. ACTEW does not intend to refer this action to DEWHA ECD Fish Management Program The ECD Fish Management Program described in Chapter 8 involves the ongoing preparation and implementation of the ECD Fish Management Plan (ActewAGL, 2009a), which involves the delivery of a suite of projects (in the vicinity of the proposed site). Actions are targeted at gaining additional information on threatened aquatic species, with necessary approvals and licenses sought should they be required. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

45 3 Location and tenure This chapter provides details on the location and tenure of the proposal including information on the location of known and potential habitat for listed threatened species and ecological communities. 3.1 Location of the proposal The proposal is located on the Cotter River approximately 18km due west of Canberra city in the ACT. The location in a regional context is depicted in Figure 3.1. The focus of the proposal is within an area colloquially known as The Cotter. While this area is not formally defined, it generally includes the area around the confluence of the Cotter, Paddy s and Murrumbidgee rivers, including Cotter Avenue, Cotter Campground, Casuarina Sands, the existing Cotter Reservoir and pumping station. 3.2 The Cotter River catchment The ACT s western boundary was largely chosen to follow the boundary of the Cotter catchment. Most of the catchment has enjoyed a high level of protection since the early 1900 s to support a safe and secure water supply for Canberra. The Lower Cotter Catchment has been subject to a much higher level of disturbance as a result of human activity when compared with the upper sub-catchments. Prior to the establishment of the ACT (and the completion of the Cotter Reservoir in 1915 which was Canberra s only water storage facility for over 40 years) approximately 3,000ha of the Lower Cotter Catchment were cleared for grazing purposes. Overgrazing resulted in serious soil erosion which was further exacerbated by rabbits, and in order to protect the catchment (and Canberra s water supply) freehold and grazing leases within the catchment were terminated by To stabilise the landscape, a program of tree planting was established with 3,000ha of pine trees (Pinus radiata) in 1931 (Australian National University, 1973). Over time more Eucalypt forest was cleared for pine plantations (1931 to 1961) however this practice ceased due to community pressure and concerns about the impacts on water quality in the Cotter River and Reservoir. Prior to the 2003 fires, 4,200ha of pine plantations were established in the lower catchment. The 2003 bushfires destroyed most of the Lower Cotter Catchment, including the pine plantations. Figure 3.2 illustrates the land use patterns adjacent to the Cotter Reservoir in the Lower Cotter Catchment. In recent years there have been various revegetation and rehabilitation activities conducted by the Government, CSIRO and ACTEW to assist in the post fire restoration. Although small pockets of pine plantations remain the majority of the catchment is now managed as native vegetation or revegetation areas, as shown. 38 WATER SECURITY MAJOR PROJECTS AUGUST 2009

46 Figure 3.1 Location of the proposal. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

47 Figure 3.2 Lower Cotter catchment land use and access trails. 40 WATER SECURITY MAJOR PROJECTS AUGUST 2009

48 3.3 Tenure The EIS (ACTEW, 2009a) included a detailed assessment titled the Land Status Report (KMR Consulting, 2008). The report identified all lands within the proposal area are either unleased land owned by the ACT Government under the custodianship of TAMS, or land that is currently leased by ACTEW. Land use in the area is consistent with uses permitted in the Territory Plan land use zones. The land that may be affected is zoned as Mountains and Bushlands, and River Corridor, with overlays for Plantation Forestry, Public Open Spaces and Parklands and the Protection of Water Supply. Table 3.1 and Figure 3.3 provide details on land affected by the proposal. Table 3.1 Land that may be affected by the proposal. District Block Land status Lessee/custodian Coree 29 Unleased/public land/gazetted park. ACT Government (TAMS Environment). Coree 34 Unleased/public land. ACT Government (TAMS Environment). Coree 210 (35) Unleased/other assets. ACT Government (TAMS Forests). Paddy s River 284 Unleased/public land. ACT Government (TAMS Environment). Paddy s River 200 Unleased/public land. ACT Government (TAMS Environment). Paddy s River 283 Unleased/public land. ACT Government (TAMS Environment). Paddy s River 178 Unleased/public land. ACT Government (TAMS Environment). Paddy s River 80 Unleased/public land. ACT Government (TAMS Environment). Paddy s River 179 Unleased/public land. ACT Government (TAMS Environment). Paddy s River 213 Unleased/other assets. ACT Government (TAMS Forests). Paddy s River 323 Unleased/public land. ACT Government (TAMS Forests). Paddy s River 322 Unleased/part public land. ACT Government (TAMS Forests/ Environment). Coree 39 Unleased/public land. ACT Government (TAMS Environment). Cotter River 13 Unleased/public land. ACT Government (TAMS Environment). Cotter River 12 Unleased /other assets. ACT Government (TAMS Forests). Cotter River 18 Unleased/public land. ACT Government (TAMS Forests). ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

49 Figure 3.3 Land potentially affected by the proposal. 42 WATER SECURITY MAJOR PROJECTS AUGUST 2009

50 3.4 Areas of conservation value and the location of known listed threatened species The proposal is located in areas of national conservation significance as deemed under the EPBC Act However, most of the direct impacts of the proposal as a whole will be on areas of low conservation value. Due to the nature of the proposal there will be permanent impacts on some areas of regional significance (along the Cotter River with the future inundation area and areas surrounding the main reservoir). Figure 3.4 shows the areas of conservation significance in relation to the proposal. There are two (2) known threatened (terrestrial) species under the EPBC Act 1999 in the vicinity of the proposal area. These are the: The vulnerable Pink-tailed Worm Lizard (Aprasia parapulchella). The vulnerable Pale Pomaderris (Pomaderris pallida). Chapter 7 provides further details on terrestrial species including the location of known and potential habitat. There are two (2) known (aquatic) threatened aquatic species listed under the EPBC Act 1999 present in the Cotter River: The endangered Macquarie Perch (Macquaria australasica) present in the existing Cotter Reservoir. The endangered Trout Cod (Maccullochella macquariensis) present in the Bendora Reservoir. The vulnerable Murray Cod (Maccullochella peelii peelii) is also a listed species and is present in the Murrumbidgee River, downstream of the confluence with the Cotter River (and the proposal). Chapter 8 provides further details on aquatic species including the location of known and potential habitat. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

51 Figure 3.4 Conservation values. 44 WATER SECURITY MAJOR PROJECTS AUGUST 2009

52 4 Proposal justification and need This chapter provides information on the specific objectives and justification for the proposal. It details the outcomes of thorough investigations over four (4) years in determining the proposal as the preferred option. The chapter also details the consistency of the proposal with the objectives and principles of Ecological Sustainable Development as indicated in the EPBC Act 1999 and the National Strategy Proposal justification and need The proposal to enlarge the existing Cotter reservoir is not new. As the ACT and Canberra have grown so has the demand for urban water. The current projections of climate change have reinforced the need for a reliable certain water supply for the region. The selection of the Enlarged Cotter Dam (the proposal) as a preferred option for improving the security of Canberra s water supply is based on the extensive studies detailed in the following sections Think water, act water The ACT Government released its water resources strategy Think water, act water a strategy for sustainable water resources management (ACT Government, 2004a) on 28 April This strategy assessed all aspects of ACT water resources, including water supply, demand management, institutional arrangements, regulation and innovation. Previous analysis indicated the ACT would need to augment the water supply by 2017 to meet demand for a population of approximately 405,000. Several issues emerged that motivated reassessment of this prediction: The current drought was developing into one of the worst on record, with experts concerned about permanent climate change for the region. The Cotter River water supply catchment was almost completely burnt in the bushfires of 2003 and was expected to deliver reduced inflows to water storages as it recovered. The ACT Government announced a population policy in the Canberra Spatial Plan (ACT Government, 2004b) of 500,000 by The Government s water strategy, Think water, act water, had set water efficiency targets of a reduction in per capita mains water use of 12 per cent by 2013 and 25 per cent by ACT Environmental Flow Guidelines (ACT Government, 2006), first introduced in 1999, were under review. As water restrictions continued, the impacts on the community were being realised as significant, requiring a decision about what levels of water restrictions would be acceptable in planning for a long term reliable water supply. Think water, act water charged ACTEW with the responsibility for assessing the reliability of the existing water supply and recommending options for new water sources for the ACT Government, and set a target of March 2005 to achieve this Future Water Options In response to Think water, act water, ACTEW launched the Future Water Options project on 30 April This study built on earlier work that had identified possible new water sources for the ACT and region as documented in the Options for the next ACT Water Source report (ACTEW, 2004a). Among more than ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

53 30 options, the report specifically highlighted and investigated three (3) main water sources for future supply to Canberra and the ACT. These options were as follows: The building of a new reservoir near Mt Tennent, south of Tharwa. The enlargement of the existing Cotter Reservoir. The transfer of water from the Tantangara Reservoir (in NSW to the ACT). ACTEW established a project team of specialists (referred to as the Future Water Options project team) in water resources management, hydrological modelling, environmental studies, planning analysis, engineering, economics and related areas to conduct this analysis. The project team comprised more than 20 engineers, scientists and other professionals drawn from ACTEW, ActewAGL, other ACT authorities and specialist contractors and consultants. Studies were undertaken to assess and evaluate environmental, social, economic and technical issues and prepare preliminary engineering designs for the various alternatives. After nine (9) months of detailed study and analysis the Future Water Options project team provided their findings and recommendations to the ACTEW Board and the ACT Government in April Findings and recommendations were provided to the ACT Government in two (2) key reports: An assessment of the need to increase the ACT s water storage (ACTEW, 2004b), predicting the future reliability of the existing supply. Future Water Options for the ACT Region Implementation Plan: a recommended strategy to increase the ACT s water supply (ACTEW, 2005b) recommending implementing options to increase the reliability of the ACT s water supply. The final recommendations of Future Water Options were to implement: The Cotter Googong Bulk Transfer, a scheme that permits surplus water from the Cotter water supply catchment to be transferred through the existing reticulation network for storage in the Googong Reservoir. The Angle Crossing Option, which allows water to be transferred from the Murrumbidgee River near Angle Crossing to the Googong Reservoir, via run of river flow into Burra Creek. Additionally, it was recommended: The remaining options of the project, enlarging the Cotter Reservoir (to 78GL), a small (43GL) or a large (159GL) Tennent Reservoir, and transferring water from Tantangara Reservoir down the Murrumbidgee River into the ACT be retained as future viable options. ACTEW undertake the necessary work program to be ready to implement one (1) of these options if required. The work program was to include a regular review of the key assumptions that the studies were based on, and technical studies to support the approval process. Additional technical analysis be undertaken for each of the reservoir options, including refining the dam design, further detailed examination of pipeline routes and additional examination of the benefits of building a new water treatment plant near the Tennent Reservoir versus transferring water from the Tennent Reservoir into the Mount Stromlo Water Treatment Plant. 46 WATER SECURITY MAJOR PROJECTS AUGUST 2009

54 4.1.3 Actions since 2005 Since 2005 a number of supply and demand management measures have been initiated including the following. Cotter to Googong Bulk Transfer The Cotter to Googong Bulk Transfer commenced operation in 2005 and has proved successful in transferring up to 12 gigalitres per year (GL/yr) from the Cotter River storages to Googong Reservoir. Further analysis identified the construction of a Murrumbidgee River pump station at Lower Cotter, in addition to Angle Crossing, could have similar benefits. This option has also been implemented. The Cotter Reservoir and Cotter Pumping Station were progressively reintroduced into operation as part of the supply system in A new 80 ML/d pump station was built in the Murrumbidgee River and is now pumping water to the Mount Stromlo Water Treatment Plant. Drought Contingency Program ACTEW is implementing a drought contingency program to supplement supplies in the continuing drought and impending Stage 4 Water Restrictions. These measures include: Upgrading the Murrumbidgee River Pump Station. Refurbishing the Cotter Pumping Station. Providing a recycled water pipeline from the Lower Molonglo Water Quality Control Centre. Optimising the North Canberra Water Recycling Scheme. The basis of the drought contingency program is to maximise use of existing water sources, primarily the Murrumbidgee River and Cotter Reservoir, through minor works and adjustments to operational procedures. Further Works The planning assumptions that underpinned the Future Water Options program were reviewed in The key assumptions reviewed included: Climate variability and climate change. Impacts on inflows to the ACT Reservoirs following the 2003 bushfires. Future population growth from the ACT and Queanbeyan and the possibility to service additional areas. Reduction targets in per capita water use set by the ACT Government. Environmental flow requirements. Acceptable levels for the duration, frequency and severity of water restrictions during drought times. The findings of this investigation showed that there were no major changes to the variables outlined above and no changes to the government recommendations made in April 2005 were required Report to Government In 2007, ACTEW reviewed the Future Water Options program (ActewAGL, 2007a). The severe impact of the protracted drought was clearly highlighted in the record low inflows recorded during The situation forced ACTEW to review Canberra s water supply and explore alternatives to ensure future water security. In July 2007, ACTEW presented the ACT Government with a number of recommendations to further secure the ACT and region s water supply (ACTEW, 2007a). The recommendations were based on extensive analyses including work completed by ACTEW in 2004 and 2005 as well as updates and additional work completed specifically for this review. More than 30 reports supported the recommendations and were made available to the public via the ACTEW website and in hard copy format. These reports included investigations into a range of matters including the following. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

55 Main reports The Cotter Dam Option (ACTEW, 2005a). The Tantangara Dam Option (ACTEW, 2005d). Water Security for the ACT and Region (ACTEW, 2007a). Community Consultation Report (ACTEW, 2007d). Enlarged Cotter Dam Update (ACTEW, 2007b). Water Purification Scheme for the ACT (ACTEW, 2007e). Angle Crossing Option (ACTEW, 2007f). Technical studies and supplementary reports Economic benefit-cost analysis of new water supply options (Centre for International Economics, 2005). The Tennent Dam Option (ACTEW, 2005c). Future Water Options Review, Water Security Program (ActewAGL, 2007a). Planning Approvals Water Security Program (CB Richard Ellis, 2007a). Methodology for evaluating Future Water Options (Centre for International Economics, 2007b). Land Status Report on the Proposed Water Security Program (KMR Consulting, 2007). Cotter Recreation Issues Paper (CB Richard Ellis, 2007b). Enlarged Cotter Dam Cost Estimates Review (Rider Levett Bucknall, 2007a). Enlarged Cotter Dam Review and Update of Cost Estimates and Comparisons (GHD, 2007a). Preliminary Ecological Review for the Proposed Water Transfer from LMWQCC to Cotter Catchment (Biosis, 2007). Seawater Desalination Concept Report (GHD, 2007b). Inputs to the Water Purification Process Preliminary Assessments (Water Futures, 2007). Water Purification Plant Options Assessment Study (CH2M HILL, 2007a). Proposed Water Purification Plant Power Supply Study for LMWQCC (PACE Consulting Engineers, 2007). Preliminary Review of Environmental Factors for Discharge of Recycled Water into Cotter Reservoir (Ecowise, 2007a). Technical Feasibility Assessment of a Water Purification Plant at Lower Molonglo Water Quality Control Centre (CH2M HILL, 2007b). Pumping Station and Pipeline from LMWQCC to Cotter Preliminary Sizing and Cost Estimates (ActewAGL, 2007b). Pumping Station and Pipeline from LMWQCC to Cotter Cost Estimates Review (Rider Levett Bucknall, 2007b). Water Quality Monitoring Program for Use of Purified Water in the Canberra Water Supply Network (Ecowise, 2007b). Salt Management Sub-Report 1 Treatment Options for Dewatering Brine Waste (CH2M HILL, 2007c). Salt Management Sub-Report 2 Review of Offsite Disposal Options Evaporation Ponds (CH2M HILL, 2007d). 48 WATER SECURITY MAJOR PROJECTS AUGUST 2009

56 Salt Management Sub-Report 3 Review of Offsite Brine Disposal Options Pipelines (CH2M HILL, 2007e). Salt Management Sub-Report 4 Review of Offsite Brine Disposal Options Landfill and Other Alternatives (CH2M HILL, 2007f). Salt Management Sub-Report 5 Discharge to Molonglo and Murrumbidgee River System (CH2M HILL, 2007g). Salt Management Sub-Report 6 Social and Human Impacts (CH2M HILL, 2007h). Salt Management Sub-Report 7 Review of Options Multi-Criteria Analysis (CH2M HILL, 2007i). These reports remain available to the public ( or by request from ACTEW. In making its 2007 recommendations, ACTEW noted that its Future Water Options report (ACTEW, 2005b) to the ACT Government included recommendations that were explicitly based on six (6) key assumptions. ACTEW undertook to monitor those assumptions and report back to the Government if any significantly changed. A major change occurred in relation to climate change and climate variability (ACTEW, 2007a). In earlier reports, based on the most pessimistic approach to analysis by the CSIRO ACTEW assumed a 30 per cent reduction in long term average inflows into our reservoirs. In fact, over the period average inflows declined by 63 per cent and in 2006, by nearly 90 per cent. ACTEW advised that the medium to long term outlook was for a further significant deterioration in the ACT s long term average inflows from a 30 per cent reduction to almost a 50 per cent reduction. The current situation is described in Chapter 1 of this report: however the 2007 predictions have been borne out and the ACT is still in a situation requiring significant new/expanded water supply infrastructure to ensure the region s future water security. ACTEW indicated to the Government that the key challenge for the medium to long term was to build additional water supply assets that could function with both much reduced long term average inflows into our reservoirs as well as with more frequent and longer drought periods. ACTEW reviewed the 2005 report and recommended a series of new investments including: Immediately increase the storage capacity of the Cotter Reservoir from 4 to 78GL. In addition to extracting more water from the Murrumbidgee at the Cotter Pump Station, the ACT Government also develop the same capacity from Angle Crossing (2005 recommendation detailed above). ACTEW also advised that it believed the ACT must have a new source of water that is largely independent of rainfall in our existing catchments and recommended that consideration be given to either the Tantangara Transfer or Water Purification Scheme. ACTEW stated that more analysis and planning were required prior to it being in a position to decide between these options. ACTEW committed to conducting these investigations and advised the ACT Government in late 2008 / early 2009 on which should be implemented Why the change in recommendations? Six (6) assumptions underpinned the Future Water Options reports of The proposal remains a preferred option as it satisfies each of these assumptions, as shown in Table 4.1. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

57 Table 4.1 Proposed enlargement of the Cotter Reservoir assumptions and performance. Assumptions Performance Options must remain viable under the Government s water conservation targets. Options must allow the continued delivery of environmental flows in accordance with ACT Government guidelines. Options must continue to provide adequate supply as catchments respond to bushfire. Options must satisfy a population which grows in accordance with the ACT Government s Spatial Plan. Options must allow ACTEW to meet its service obligations to customers. Options must be robust and be able to withstand current predictions for projected climate change and climate variability. Recent assessment of these assumptions has shown several trends including: A deterioration in inflows into water storages. A pessimistic future climate outlook. Population increases greater than those foreshadowed in the Canberra Spatial Plan (ACT Government, 2004b). These predictions reinforce the need for the ACT Government to have in place a diverse range of measures, including the proposal, to ensure that the ACT community is protected from severe water restrictions and has a secure water supply for future generations. Climate change and climate variability Based on the same cautious approach that ACTEW has previously taken to the analysis conducted by CSIRO, but adjusted with new data from the last nine (9) years, average annual inflows were estimated to be approximately 105GL a year to the three (3) main ACT reservoirs. In fact the last three (3) years has seen an average inflow into the ACT s water storages of 50GL. This represents a substantial reduction from the long term average inflows (approximately 200GL per year) and a further reduction from the average annual inflows that was assumed based on CSIRO climate change research from the 2005 Future Water Options report (132GL a year). Figure 4.1 demonstrates long term inflows into ACT storages. Figure 4.2 demonstrates the reduction in inflows to three (3) ACT storages over the last nine (9) years. The continued decline in inflows and the continuing uncertainty of climate change, suggests prudent investment to ensure future water security for the ACT. 50 WATER SECURITY MAJOR PROJECTS AUGUST 2009

58 Figure 4.1 Long term inflows into Corin, Bendora and Googong Reservoirs ( ). Figure 4.2 Annual inflows into Corin, Bendora and Googong Reservoirs ( ). ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

59 The ACT currently require to extract 65 to 70GL a year to meet customer demand. Approximately 30GL are lost due to evaporation, spills from reservoirs after major storm events and environmental flows. In light of this the ACT require approximately 100GL to flow into the storages every year. Water supply planning can not be based on average inflows of 100GL being available each year. This is because both the CSIRO analysis (Commonwealth Scientific and Industrial Research Organisation, 2003) and the modelling supporting ACTEW s 2007 report show that within that average, there will be droughts both longer and drier than the current drought. Such droughts are expected to occur with significantly greater frequency than in the past. The inflows into our storages for 2006 were 26GL, in 2007 were 66GL and in 2008 were 59GL. These years remain significantly below our long term average and even lower than the 105GL ACTEW estimated in its 2007 report to the ACT Government. As stated previously, and now further reinforced by the climatic conditions of the past three (3) years, the key challenge for the medium and long term is to build additional water supply assets. Additional assets must have the capacity to store and function with a much reduced long term average inflows, and withstand more frequent drought conditions which are longer and drier than recent/current experience, without the need to impose high level water restrictions for extended periods. ACTEW investigations to date demonstrate that there is a need for additional water supply capacity. The financial cost of this extra capacity is an essential investment that was justified (and accepted by the ACT Government) on the grounds of ensuring the ACT and region s water security. Since ACTEW s 2007 report to the ACT Government (ACTEW, 2007a), which noted some fundamental changes to climate predictions, ACTEW has been undertaking an ongoing review of available evidence to more accurately forecast the climate scenario in the short to medium term. Reports from CSIRO (Commonwealth Scientific and Industrial Research Organisation, 2003), CSIRO and the Bureau of Meteorology (Commonwealth Scientific & Industrial Research Organisation and Bureau of Meteorology, 2007), the NSW Government and the Murray Darling Basin Commission (Murray-Darling Basin Commission, 2008) were utilised to support a scenario that predict hotter and drier weather for the foreseeable future, with little chance of improvement in rainfall and the likelihood of significantly above average temperatures. Population increases Population projections have changed, with predictions by the Australian Bureau of Statistics (ABS) of increases greater than were foreshadowed and used in the Canberra Spatial Plan (ACT Government, 2004b). Using the high growth scenarios from the ABS, the 2032 population of the ACT and Queanbeyan is now predicted to be 562,152 persons, an increase of 46,000 persons (approximately 9 per cent) over the Spatial plan predictions. If cross border water supply was required, this figure would include outlying areas of the ACT and the 2032 population would increase further to 570,585 persons (in excess of 10 per cent increase). The ACT Government s Think water, act water strategy (ACT Government, 2004a) prescribes the use of high population growth projections by stating that work being done to predict when new water supply infrastructure will be needed will therefore be using these higher growth projections for contingency planning to ensure that, if increased water supply is needed, necessary planning and design will be done well in advance of the need to begin construction. This strategy remains to be Government policy, and the further increases in population projections indicate that prudent supply planning continues to be necessary Criteria for new water supply assets The proposal was selected as a preferred option as it satisfies the criteria for new water supply assets. These criteria and the ability of the proposal to meet them are provided in Table WATER SECURITY MAJOR PROJECTS AUGUST 2009

60 Table 4.2 Criteria for new water supply assets. Criteria Performance Maximising the use of existing service infrastructure, both ACTEW s and others. Increasing the diversity of sources of water (both rainfall and rainfall independent options). Ensuring that adopted choices include at least one (1) source of water which is not dependent on rainfall in ACTEW s water supply catchments. Maximising operational flexibility to provide backup capabilities in the event any part of the system is out of operation for whatever reason. Providing a net economic benefit to the community. Optimising outcomes from capital and operational costs and minimising the consequent flow-on cost to consumers. Minimising the environmental impact of the water supply solutions. Economic benefit approach ACTEW s report to the ACT Government (ACTEW, 2007a) set out a net economic benefit approach which was also applied in the Future Water Options report (ACTEW, 2005b; Centre for International Economics, 2005, 2007a, 2008). The net economic benefit of implementing each scenario is calculated by deducting the capital and operating costs of each supply option from the gross economic benefit to the community arising from any reduced time in drought restrictions (further details are provided in Section 5.11 of the EIS). Gross economic benefits The costs of restrictions have been updated since the 2007 report (Centre for International Economics, 2008) and are summarised in Table 4.3. Table 4.3 Previous and revised costs of water restrictions ($ million/yr). Temporary Water Restriction Level Restriction costs used in previous modelling (Stage 4 costs*3.5) Restriction costs used in current modelling Stage 1 $ 5.6 $ 7.0 Stage 2 $ 44.9 $ 48.8 Stage 3 $ 62.1 $ Stage 4 $ $ Using these costs, ACTEW has examined three (3) different climate scenarios to assess the benefits associated with the options proposed. It is important to note that with different climate scenarios, different combinations of water supply options provide the optimum solution to achieve the desired level of security. With increased water security, harsher stages of water restrictions would be avoided, except during extremely adverse climatic conditions. The proposal aims to minimise the duration the ACT community spends within the harsher temporary water restrictions. As described in the following sections the proposal is an integral component of future water supply solutions. Three (3) scenarios have been chosen as the future climate is more uncertain than any other assumption used in ACTEW s water supply planning to date. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

61 4.1.7 Water Security Options under various scenarios Climate Scenario 1:2030 climate If the future climate is similar to the predicted 2030 climate change scenario (i.e. a reduction in annual inflows of approximately 50 per cent) then the combination of the proposal and the Murrumbidgee to Googong Water Transfer, is predicted to successfully reduce the time the ACT will spend in severe water restrictions (ACTEW, 2007a). The addition of the Tantangara Transfer provides even further reduced time in restrictions. Climate Scenario 2: Repetition of the last six years climate The reduced inflows in the past few years have been much worse than that predicted by the 2030 climate change scenario outlined above. In fact since 2001, the decrease in inflow has been approximately 65 per cent. As ACTEW has previously stated, in addition to the proposal, increased pumping from the Murrumbidgee River speeds drought recovery and keeps storages at a higher level. It also indicates that the Tantangara Transfer, when teamed with increased Murrumbidgee pumping, is the best performing option in the early stages of recovery, assuming it can be implemented in the timeframe required. This analysis reinforces the need to increase pumping from the Murrumbidgee River, with the addition of the Tantangara Transfer to provide additional diversity and security, as shown in Figure 4.3. Figure 4.3 Projected storage with climate continually repeating. Climate Scenario 3: Repetition of 2006 Climate If the climate experienced in 2006 is more typical of the future ACT climate, permanent Stage 4 restrictions are expected unless all feasible options the proposal, Murrumbidgee to Googong Water Transfer, Tantangara Transfer scheme and the large Water Purification Scheme are implemented as soon as practical. Even with all these major infrastructure items in place it will take some years before restrictions are no longer required. 54 WATER SECURITY MAJOR PROJECTS AUGUST 2009

62 Figure 4.4 shows that given a repeat of the 2006 climate scenario, the ACT would be in Stage 4 restrictions and eventually run out of water somewhere between 2016 and The graph shows the importance of the Tantangara Transfer scheme, and the ability to pump this water via the Murrumbidgee to Googong Water Transfer, to the ACT s long term water security. The figure also highlights that should no action be taken and the 2006 climate becomes the norm Canberra is likely to run out of water by 2013, or be faced with more severe water restrictions than what is currently being experienced. Figure 4.4 Projected storages with repeated 2006 climate. To avoid a situation where Canberra could potentially run out of water, or experience frequent and protracted periods in more stringent restrictions, it is important to consider recent climate history as a potential indicator of long term future climate trends. In this climate scenario the importance of the Tantangara Transfer becomes apparent. In Figure 4.4 the hydrological modelling demonstrates that building the proposal, the Murrumbidgee to Googong Water Transfer and Tantangara Water Transfer (orange line) significantly delays the ACT running out of water. While there have been some suggestions that this climate scenario is unlikely, the climate of the past three (3) to five (5) years indicates that a trend towards this climate could be realised. Evidence of this change has been seen in the ACT over the past three (3) years: Inflows in 2006 were 26GL. Inflows in 2007 were 66GL. Inflows in 2008 were 59GL. This demonstrates a significant reduction compared to historical long term average flows. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

63 4.2 Proposal objectives The primary objective of the proposal is to increase the water security of the ACT and region by providing increased storage capacity of potable water in an Enlarged Cotter Dam. Secondary objectives of the proposal include: Long term sustainability of threatened fish species in the Cotter catchment. Ensuring dam safety to protect community and workers in and around the proposal site. Informing the community regarding the development of the proposal, including appropriate conservation of cultural and natural heritage. Maintaining appropriate environmental flows downstream of the proposal. These objectives are intended to form a framework to guide the development of the proposal and ensure it is delivered in accordance with the objectives and principles of National Strategy for Ecological Sustainable Development (Department of the Environment, Water, Heritage and the Arts, 1992) and the EPBC Act Objectives and principles of the EPBC Act 1999 The Commonwealth EPBC Act 1999 provides a national scheme for environment and heritage protection and biodiversity conservation. In particular, Section 3 and 3A of the Act provides guiding Ecologically Sustainable Development objectives and principles to be addressed in the assessment of proposed actions to which a significant impact may occur. ACTEW have addressed each of these principles for the proposal, as detailed below. Compliance with the principles has been assessed on the permanency of the proposal and as such take into account a whole of life approach to the proposal from design and construction to inundation and operation. This section specifically justifies the proposal against these assessment criteria Objectives Section 3 of the EPBC Act 1999 provides the overarching objectives of the Act are discussed as follows: To provide for the protection of the environment, especially those aspects of the environment that are matters of national environmental significance There are five (5) species of national environmental significance that have been identified by the Commonwealth and each has been assessed in relation to the significant impact criteria under the EPBC Act Specialist assessments for both terrestrial and aquatic biodiversity have determined that the proposed action, the construction, inundation and operation of the proposal, will not have a significant impact on these items of national environmental significance. Each report provides recommendations to manage the risk of any significant impact through the provision of a number of mitigation measures. The environmental management strategies will form part of the Environmental Management Plan (for construction and operations), which will be prepared and implemented to provide a framework for environmental management during the construction and operation phases of the proposal. The plan will contain site-specific procedures, work method statements, corrective action management and control plans to manage each environmental issue. To promote ecologically sustainable development through the conservation and ecologically sustainable use of natural resources The proposal incorporates measures to minimise resource consumption and waste generation, and encourage reuse and recycling. These measures will be implemented as an integral component of the CEMP detailed in Section To promote the conservation of biodiversity As part of the EIS (ACTEW, 2009a) and PER processes, specialist studies have been undertaken to assess the potential impacts of the proposal on biodiversity and recommend ways it may be conserved. ACTEW will deliver the proposal in line with all recommendations to protect threatened species and promote the conservation of biodiversity. These measures are described in detail in Chapter 7 for terrestrial species and Chapter 8 for aquatic species. 56 WATER SECURITY MAJOR PROJECTS AUGUST 2009

64 To provide for the protection and conservation of heritage The enlargement of the Cotter Reservoir will be delivered inline with prescribed measures for the protection and conservation of heritage items and values. A full Aboriginal and non-indigenous cultural heritage impact assessment has been undertaken by Navin Officer Heritage Consultants Pty Ltd as part of the EIS. The assessment included a detailed field survey to identify all places and objects of cultural heritage value within the area around the existing reservoir, including areas to be inundated or may be disturbed by construction activities. Representatives from recognised Representative Aboriginal Organisations, the Buru Ngunnawal Aboriginal Corporation, Consultative Body Aboriginal Corporation, Little Gudgenby River Tribal Council and the Ngarigu Currawong Clan participated in the assessment of Aboriginal cultural heritage places and objects. The outcomes of the assessment concluded there are no cultural heritage items within the study or proposal development areas listed on the National Heritage List, the Commonwealth Heritage List or the Register of the National Estate. Therefore, there are no constraints relating to the heritage provisions of the various Commonwealth Acts which establish and define these lists. Furthermore, there are no known or anticipated potential impacts of the proposal on cultural heritage values located on Commonwealth lands or lands controlled by Commonwealth authorities. A Conservation Management Plan (CMP), developed as part of the CEMP and approved by the ACT Heritage Council, will be used to manage all issues in relation to protection and conservation of cultural heritage values. The plan will include procedures relating to displaying sensitivity in conduct of personnel for the traditional owners and their values of the land, and those relating to procedures for any unexpected finds. Other approvals for the proposal required by ACT legislation will be sought (refer Section 2.3). To promote a co-operative approach to the protection and management of the environment involving governments, the community, land-holders and indigenous peoples The proposal will involve a co-operative approach to the protection and management of the Cotter River and the surrounding environment involving government, the community, landholders and indigenous peoples. The existing Cotter Reservoir and Cotter catchment are located within the Namadgi National Park. The lands are managed by ACT Parks, Conservation and Lands (PCL) who are the custodians and land managers for biodiversity conservation and overall park management and operations. The Ngunnawal people are the traditional owners of the land and representatives are engaged through PCL on an employment basis within the park, and through ACTEW in the development of the EIS. The reservoir itself is managed by ACTEW, with operations and maintenance activities being undertaken by ActewAGL. The users of the land are the community who utilise the area for the national park, its rivers and swimming areas for recreational activities and spiritual enjoyment. All land within the proposal area is either unleased territory land owned by the ACT Government under the custodianship of PCL or leased by ACTEW. All management activities for the Cotter Reservoir and catchment are undertaken in accordance with the ACT Government s Lower Cotter Catchment Strategic Management Plan (ACT Government, 2007b). The aim of the plan is to restore the lower Cotter catchment to a natural and stable condition that supports the delivery of clean water and that also allows for a range of activities that are compatible with the protection of water resources. The plan recognises the importance of the Lower Cotter Catchment as a water supply catchment for Canberra and sets out the framework for the management of the catchment and activities therein in light of a number of strategic requirements, including domestic water supply. Throughout the delivery of the proposal there will be numerous opportunities for engagement with the government, community, landholders and indigenous peoples as has been to date and will continue throughout the design, construction and operation of the reservoir. The management of the completed reservoir including access would need to be managed jointly between the various groups. Chapter 9 provides further information. To assist in the co-operative implementation of Australia s international environmental responsibilities The proposal will assist in the co-operative implementation of Australia s international environmental responsibilities and commitments. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

65 Australia s international responsibilities relate to the commitments made in signing of the Kyoto Protocol in As a signatory, the Australian government is committed to a reduction of 20 per cent of greenhouse gases by ACTEW are committed to voluntarily minimising all greenhouse gas emissions associated the construction and operation of the proposal. This commitment is also in accordance with the objectives on a regional level, the ACT Climate Change Strategy, Weathering the Change 2007 and will assist in meeting ACT, Australian and international reduction targets. To recognise the role of indigenous people in the conservation and ecologically sustainable use of Australia s biodiversity, and To promote the use of indigenous peoples knowledge of biodiversity with the involvement of, and in co-operation with, the owners of the knowledge ACTEW recognises the important role of Aboriginal people in the sustainable use of natural resources. Their guidance has been sought and employed throughout the planning approvals phase for the proposal. To gain an understanding of the conservation of Aboriginal values, ACTEW sought the guidance of all ACT Aboriginal organisations with an interest in the proposal. Four (4) local Aboriginal organisations responded with an objective to represent traditional cultural values and interests within the ACT. These groups consisted of the Buru Ngunnawal Aboriginal Corporation, Consultative Body Aboriginal Corporation, Little Gudgenby River Tribal Council and the Ngarigu Currawong Clan. These groups are recognised as Representative Aboriginal Organisations under the ACT Heritage Act Personnel from each group were invited to participate in the comprehensive field (archaeological) survey program and represent the interests of their group throughout the proposal in the development of the EIS. However, due to limitations in insurance cover, representatives from the Consultative Body Aboriginal Corporation were unable to participation in field survey. There was continued consultation with the Corporation on the field results, draft reports and in the provision of recommendations for the EIS. Throughout the field survey, the rationale for the selection of sample survey areas was discussed with each representative and opportunities to nominate additional areas were discussed. The potential archaeological values of the proposal area were also discussed, together with the potential impacts of the proposal. ACTEW has and will continue to encourage the ongoing involvement of Aboriginal peoples in key aspects of the proposal Principles of Ecologically Sustainable Development The following provides an assessment of the proposal against the principles in Section 3A of the EPBC Act 1999 and take into account the outcomes of this PER. Decision-making processes should effectively integrate both long term and short term economic, environmental, social and equitable considerations The ACT Government in October 2007 announced the proposal as part of its response to ACTEW s recommendations to address and secure the regions water supply (ACTEW, 2007a). The recommendations are based on the findings of the Future Water Options project completed by ACTEW in After examining each option and in varying combinations, ACTEW determined the proposal is a high-priority option as it took into consideration long and short term economic, environmental and social issues. The proposal: Will provide the greatest net economic benefit to the community and it will deliver amounts of water similar to those projected for the large Tennent Reservoir option, at half the capital cost and less risk, and be brought into operation more quickly. Was assessed by the fish impact study conducted by Lintermans (2005) as having the lowest environmental impacts of any of the reservoir options. Will have minimal impact on threatened aquatic fauna or terrestrial flora and fauna populations. Will result in environmental benefits derived through improved catchment condition and improved understanding and habitat opportunities for endangered species within the reservoir. 58 WATER SECURITY MAJOR PROJECTS AUGUST 2009

66 Will lead to economic and social benefits for the ACT community as a result of less time spent in harsher levels of water restrictions. If there are threats of serious or irreversible environmental damage, lack of scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation. Specialist assessment has been undertaken in the development of this PER to address the requirements for identifying any knowledge gaps or limitations that exist in undertaking the assessment and report preparation. Where knowledge gaps exist, monitoring and investigation programs have already been put in place by ACTEW to minimise any risk of serious or irreversible environmental damage. These monitoring and investigation programs were initially developed as part of the preparation of the EIS (ACTEW, 2009a), and have been expanded to ensure they fulfil Commonwealth requirements. These programs have been initiated to provide clarification to ensure measures to prevent environmental impact or degradation due to the proposal will not occur. The principle of inter-generational equity that the present generation should ensure that the health, diversity and productivity of the environment is maintained or enhanced for the benefit of future generations The enlarged reservoir will provide a clean, reliable and equitable water supply for the ACT. Increasing the storage capacity of the Cotter Reservoir from four to 78GL is part of a suite of infrastructure projects proposed by ACTEW to diversify the ACT water supply and provide greater security into the future. The Cotter Reservoir became the primary water supply for the ACT after the 2003 bushfires severely impacted on water quality and supply from the Corin Reservoir and its catchment. At this time, the Mt Stromlo Water Treatment Plant was augmented to provide increased treatment levels for the raw water being received from the Cotter Reservoir. The enlargement of the Cotter Reservoir is a priority option for ACTEW as: The location of the proposed reservoir will enable the capture of more inflows from the Cotter catchment. The proposal will allow greater control of the duration, volume and quality/temperature of environmental flow releases along the Cotter River. The proposal will impact a largely modified/disturbed area in preference to the more pristine environments of the catchments of Bendora and Corin (within the Namadgi National Park). The proposal will provide ongoing rehabilitation and restoration of highly disturbed (pine/bushfire) areas. This will ensure water collected in the reservoir from the supply catchment is of higher quality and hence requires less treatment. Construction and operational greenhouse gas emissions can and will be offset. The proposal satisfies the principles of ecologically sustainable development. Furthermore, the enlargement of the Cotter Reservoir has a number of beneficial effects namely the ongoing rehabilitation and revegetation of the Lower Cotter Catchment. These issues were detailed as part of the EIS and are as follows: An upgrade of the existing Cotter precinct recreational facilities will be undertaken as part of a recreation planning process by ACTEW. There will be an opportunity to reintroduce the community to the Cotter precinct. Due to the scale and duration of the proposal within the ACT, it is envisaged that construction activities and operation of the reservoir will attract visitors. A viewing platform, visitor information and associated facilities will be provided to enhance this opportunity. Community and user group consultation will continue to be undertaken throughout the proposal to meet the needs of the community now and into the future. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

67 The conservation of biological diversity and ecological integrity should be a fundamental consideration in decision-making Decisions on the proposal, with the potential to impact biological diversity and ecological integrity of the Cotter River and the surrounding region, have been informed by extensive specialist studies and based on expert recommendations. Chapters 7 and 8 detail the specific management, mitigation measures and offsets that will be applied to the proposal to ensure and that the biological diversity and ecological integrity of the area are maintained throughout the lifecycle of the proposal. These measures will be fully implemented through the development of an environmental management plan, for the construction and operations aspects of the proposal. Furthermore, ACTEW will ensure that decisions made on each of the above measures are consistent with proposal objectives and environmental management strategies and the National Recovery Plans for these species, where applicable. Improved valuation, pricing and incentive mechanisms should be promoted Through the EIS and PER, ACTEW have identified the environmental and other consequences of the proposal and specified mitigation measures to manage adverse impacts. During construction, these measures will be delivered through the development and implementation of Environmental Management Plans for the proposal. ACTEW has valued the cost of these plans and accounted for this component as part of the capital cost. At the completion of construction, ongoing monitoring (particularly of aquatic biodiversity and water quality) is a condition of licensing. This will be factored into operating costs. All costs associated with the design, construction and operation of the proposal will be reflected in the price customers pay for the supply water, under direction of the Independent Competition and Regulatory Commission. To complement supply-side incentive mechanisms, ACTEW will continue to encourage a reduction in potable water use for both residential and commercial/industrial use through demand management policy, including Permanent Water Conservation Measures and Temporary Water Restrictions when necessary due to climatic conditions and a tiered pricing structure with higher prices charged for water consumption above specified targets. 60 WATER SECURITY MAJOR PROJECTS AUGUST 2009

68 4.4 Consequences of not proceeding The consequences of not proceeding with the proposal would result in not providing the ACT with the diversity required for the future security of its water supply and place the future use of ACT water resources at risk. This would result in a number of significant social, environmental and economic consequences for the ACT including: Not meeting the requirements for providing certainty for ACT water supply options and sources. The direct social detriment and inequity resulting from measures that failed to deliver adequate, reliable and affordable water for the ACT community. A weakening of community cohesion with political and civic tension, non-preferred family dispersion, intergenerational family caring and less communal activity in brown landscapes. The cost to the community of ongoing water restrictions. This would be increasingly detrimental to the Canberra region over the coming years. The health and well-being costs to the community in terms of increases in anxiety and stress, lower levels of affordable outdoors sports and recreational activities. A green environment has positive social and psychological impacts to a community when compared to a brown environment, particularly where there are impacts on health and personal recreational activities (such as private gardening, swimming in the Cotter and Murrumbidgee Rivers). The cost of repairing drought damaged private or public sport fields, parks, roadside reserves and watercourses. The result of negative publicity for the ACT as the bush capital/garden city image resulting in a reduction in tourism, which is the regions major export. Community wide social and economic costs associated with water restrictions. Significant limitations placed on industries reliant on potable water, reducing the attractiveness for investment in and establishment of businesses in the ACT. Not proceeding with the proposal would also result in lost opportunities for positive socio-economic impacts for the ACT. In particular, if the proposal does not go ahead there will be limited increase in employment opportunities or demand for manufacturing services provided during the design and construction phases of the proposal. This would result in limited opportunities for the services of specialist tradespersons, engineers and consultants and unskilled labour, office support, steel fabricators, suppliers of concrete, building and fencing supplies and vehicle suppliers. If the proposal does not proceed, an opportunity to stimulate the local economy would be lost. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

69 5 Options and alternatives This chapter provides an analysis of the options and alternatives considered by ACTEW to secure the ACT s urban water supply. 5.1 Options for the next ACT water source When considering the need for new water sources investigations are commonly based on estimates of population growth, existing water consumption, environmental flows and assuming the worst possible drought (when compared to historic records). Initial consideration of the future water needs of Canberra estimated that new water sources would be required when the population of the ACT and Queanbeyan reached 405,000. The ABS predicts that this level will be reached in In April 2004 ACTEW published a report entitled Options for the Next ACT Water Source (ACTEW, 2004a). This report identified it was necessary to include other important factors such as the effects on the availability of water due to bushfires, impacts of climate change and climate variability, water consumption patterns and the possibility of future requirements to supply water to neighbouring towns and new development estates in surrounding NSW. In conducting and reassessing the ACT future water requirements the report examined a wide range of options for a new source of water. In doing this it also re-assessed previously proposed schemes and investigated new options. The full lists of options were reviewed and grouped into shortlisted and not shortlisted options based on their relative merits. The following is an outline of the options considered. Table 5.1 Options identified in Options for the Next ACT Water Source. Shortlisted options Options not shortlisted Enlarged Cotter Reservoir, with water supply to the Mount Stromlo Water Treatment Plant. Tennent Reservoir, with water supply to Mount Stromlo or Tuggeranong Water Treatment Plants. Coree Reservoir, with four (4) different options: Coree arch to Bendora gravity main. Coree arch to Coree gravity main. Coree embankment to Bendora gravity main. Coree embankment to Coree gravity main. Tantangara Transfer with four (4) different options: Pump to Cotter River. Tunnel. Yaouk Valley to Porcupine Creek. Yaouk Valley gravity pipeline. Water farm. Cross border supplies from sources other than the Tantangara Reservoir. Groundwater. Stormwater reuse. Riverlea Reservoir on Paddy s River. Welcome Reef Reservoir on the Shoalhaven River in NSW. Carwoola Reservoir on the Molonglo River. Lower Cotter Catchment Reservoir (below Bendora). Enlarged Corin Reservoir. Enlarged Bendora Reservoir. Enlarged Googong Reservoir. Raising Googong Spillway (fuse plug). The options shortlisted were chosen for their ability to feasibly supply water to the ACT under a set of six (6) key planning assumptions detailed in Table 4.1, in Chapter WATER SECURITY MAJOR PROJECTS AUGUST 2009

70 5.2 Assessment of social, economic and environmental parameters Analyses conducted for the Future Water Options (ACTEW, 2005b) project utilised the principles of Triple Bottom Line (inline with those methods described by Department of the Environment, Water, Heritage and the Arts, 2003 and Group 100, 2003) to assess the social, economic and environmental impacts of the proposed options. In order to comprehensively evaluate future water options, assessment criteria were developed based on the sustainability dimensions set out by the ACT Office of Sustainability in the document People Place Prosperity: a policy for sustainability in the ACT (ACT Government, 2003) in consultation with industry experts and interested members of the community. The 12 assessment criteria provided in Table 5.2 include the social, economic and environmental factors which require consideration (ACTEW, 2005b). Table 5.2 Sustainability criteria for evaluation of Future Water Options (ACTEW, 2005b). Criteria Risk to public health. Heritage and cultural values. Landscape and amenity values. Recreational opportunities. Cost and affordability. Reliability. Employment creation. Distribution of costs and benefits. Effect on aquatic ecology. Effect on terrestrial ecology. Greenhouse gas emissions. Intrinsic value. TBL Category Social. Social. Social. Social. Economic. Economic. Economic. Economic. Environment. Environment. Environment. Environment. The above criteria are designed so that: There is equal consideration of social, economic and environmental factors. They represent the key issues involved in the comparison of the options as identified in public and agency consultation, can be measured for the different options, and cover the sustainability areas to ensure proper account is being taken of all factors to achieve objectives. They are able to show a difference for the various options. They do not overlap, in order to avoid the problems of double counting. They reflect local, regional, basin-wide, national and worldwide concerns and interests. They provide a direct measure of inter-generational equity. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

71 5.3 Future Water Options 2007 review In response to the recent reduction in inflows, ACTEW s 2007 report to Government (ACTEW, 2007a) undertook another review of water supply options for Canberra. The review assumed that demand management targets were met and considered all the previous water supply options (including those outlined above and the findings of the strategy Future Water Options, (ACTEW, 2005b)), including: The do nothing option. Enlargement of the Cotter Reservoir. Tennent Reservoir. Tantangara Transfer. Angle Crossing option (Murrumbidgee to Googong Water Transfer). Seawater desalination. Groundwater. Water purification scheme. Stormwater. Rainwater collection (private tanks). Grey water use. Other non-potable reuse options. Accelerated demand management. Cloud seeding. Watermining TM. Evaporation control on reservoirs. The feasibility of these options was determined based on their compatibility with the six (6) key planning assumptions, including any changes to these assumptions that had occurred since 2005 and the social, environmental and economical implications of their implementation. Following this process those ranked highest were recommended to the ACT Government as viable options for future water supply sources. Those options not recommended may be employed to minimise the demand for potable water and assist the community in meeting ACT Government target reductions for potable water use. Others may also be retained should they be needed in the future The do nothing option A key aspect of the Future Water Options Study was an assessment of the need for an additional water supply option. The report An Assessment of the Need to Increase the ACT s Water Storage (ACTEW, 2004b) determined that new scientific knowledge of the potential combined effects of climate change and bushfire impacts has meant that additional water storage will be needed sooner than previously expected. The predictions of future conditions using the six (6) planning assumptions show that reservoir storage levels would become low to very low in periods of drought. The ACT will not run out of water, but only if severe and onerous water restrictions are applied, or unless some unforeseen event occurs. Furthermore, over the coming years, water restrictions will be increasingly detrimental to the community and at the same time become less effective. This is because restrictions would come on top of a substantial reduction in per capita water use through meeting the water efficiency targets, which within themselves will require permanent water restrictions. 64 WATER SECURITY MAJOR PROJECTS AUGUST 2009

72 Unless the ACT is willing to accept the regular recurrence of water restrictions of a severity and frequency unprecedented in planning elsewhere in Australia, then additional water supply is required, and the do nothing option is not feasible. Full details of the option assessment are contained in Water security for the ACT and region Recommendations to the ACT Government, (ACTEW, 2007a). A summary of the options considered are provided below New reservoir in the Cotter Catchment As part of the Future Water Options studies in 2005, four (4) alternatives involving the Cotter catchment were considered (ACTEW, 2005b): Construction of a new 73GL Coree Reservoir (instead of the proposal), upstream from the existing Cotter Reservoir. Retain the existing reservoir, plus greater use of environmental flow releases from Bendora Reservoir. Enlargement of the existing reservoir to a 45GL Cotter Reservoir. Enlargement of the existing reservoir to a 78GL Cotter Reservoir (i.e. the proposal). The Coree Reservoir option has been found to be more expensive to construct than the proposal as additional concrete is required due to the wider valley. The pump station and pipeline that would be required for this option are also more expensive as a new power supply would need to be provided. As the proposal would be downstream of a new Coree Reservoir, it will capture more inflows (larger catchment). The proposed Coree Reservoir would be higher in elevation and would have slightly less energy costs from pumping. From a water quality perspective, a new Coree Reservoir would have marginally better quality water, but with the completion and upgrading of the Mount Stromlo Water Treatment Plant, water from lower Cotter can easily and successfully be treated. A new Coree Reservoir is likely to have negative impacts on endangered fish in the existing Cotter Reservoir as it would prevent upstream passage to existing river habitat and breeding grounds. The 2005 studies also recommended that ACTEW include the review of existing infrastructure such as pipelines, pumping stations and water treatment plants associated with these options to determine upgrade needs to convey the water to various locations within the Canberra and Queanbeyan water supply system. In this review the Cotter Reservoir options were refined and it was determined that the best option would be to construct a separate dam wall downstream of the existing dam wall as opposed to incorporating the existing structure in a new one (raising the existing dam wall). The primary reasons for this recommendation were: The volume of the existing dam wall was too small to provide any financial benefit or saving in construction cost. Technical and practical difficulty associated with ensuring an adequate bond between the existing dam wall and a new wall. Concerns in relation to the quality of the concrete in the existing dam wall and whether it could withstand the load of a much larger structure on it. Construction issues associated with incorporating the existing intake tower and pipe work would have added a significant degree of complexity which offset any gains from use of the old reservoir. With the existing Cotter Reservoir back into operation there are no significant benefits through greater use of environmental flow releases from Bendora Reservoir. The smaller (45GL) Cotter option was primarily discarded on the basis of hydrological assessment (it did not add sufficiently to future water yield) and because of a potential fish passage threat to the existing Macquarie Perch population. Extensive modelling of the 78GL Cotter Reservoir option did not show the same potential fish passage problem as indicated with the 45GL option. Further studies have been conducted since 2005 to ensure fish passage will not be affected by the proposal. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

73 The Future Water Options Review (ActewAGL, 2007a) included a detailed review of the proposal which led to the Enlarged Cotter Dam: Update Report (ACTEW, 2007b) This report reconfirmed the proposal as a favoured infrastructure option to secure the ACT s water supply. A summary of the performance of any new reservoir (i.e. not only the proposed ECD option) in the Cotter catchment against the principles of Triple Bottom Line is provided in the following table. Table 5.3 New reservoir in the Cotter catchment summary of performance. TBL category Performance of option Social Economic Environment Existing reservoir site on Territory land. Positive community sentiment arising from a reliable water supply. No increase in diversification. Impacts on landscape and visual amenity. Disturbance to community during construction, particularly road users, local residents and users of recreational facilities within and adjacent to the Cotter precinct. Requires appropriate management of heritage and cultural values High yield at relatively low cost. Provides net economic benefit through less frequent occurrence and severity of water restrictions. Creates local employment opportunities. Comparatively reliable water supply. Requires pumping to Mount Stromlo Water Treatment Plant. Minimal environmental impacts. Largely disturbed area which has been heavily impacted by bushfire and previous forestry activities. Requires management of threatened fish species. Removal and inundation of native and exotic vegetation. Impacts on the habitat and potential habitat of threatened species. Greenhouse gas emissions associated with construction and operation of the reservoir Tennent Reservoir One (1) of the alternative reservoir options considered as part of the Future Water Options project was the construction of the Tennent Reservoir on the Gudgenby River in the Naas Valley (ACTEW, 2005c). The construction of this reservoir would also require building a new water treatment plant on site or pumping of water to the existing Mount Stromlo Water Treatment Plant. The proposed reservoir included a number of complexities that would need further assessment and would translate into a long design and planning lead time before implementation including: The Naas Valley has an existing community of rural lessees who would need to be relocated if a reservoir was built. The site has an existing road linking Tharwa with the Boboyan Road, which would need to be entirely relocated. The site has areas of Yellow Box Grassy Woodlands, which have national significance (EPBC listed communities). The woodlands are also home to several threatened species of birds. The site has a number of European and Aboriginal Heritage sites. 66 WATER SECURITY MAJOR PROJECTS AUGUST 2009

74 Apart from these matters, the key issue against this option is the uncertainty of flows in the Gudgenby river system. This river has long term average flows of approximately 57GL per year, compared to 138GL per year for the Cotter River. Over the last six (6) years the Tennent catchment inflows have reduced by 70 per cent compared to 40 per cent in the Cotter Reservoir and 35 per cent for Tantangara reservoir. This provides a clear indication that the Gudgenby River flows are much less resilient to drought than the other river systems considered. To further illustrate this reduction, it is worth considering that had the Tennent Reservoir been in place in 2006 it would have received inflows of less than six (6) GL in total. This option is also the most expensive reservoir option that was considered. In 2005, capital costs for the Tennent Reservoir were estimated at $ 292 million (159GL reservoir), with annual operating costs likely to be similar or slightly lower than the existing water supply system. Preliminary investigations and modelling predict five to ten years to build and fill the reservoir (assuming average annual inflows against predicted climate change reductions). ACTEW recommends retaining the Tennent Reservoir site as a future water supply option for the ACT. Further reading on the Tennent Reservoir is provided in the Tennent Option Report (ACTEW, 2005c). A summary of the performance of the Tennent Reservoir against the principles of Triple Bottom Line is provided in the following table. Table 5.4 Tennent Reservoir summary of performance. TBL category Social Economic Environment Performance of option Positive community sentiment due to diversification. Largest reservoir option available. Uncertainty of future inflows. Leaseholder relocation necessary to provide protection to the reservoir. Catchment remediation necessary to protect water quality. Road relocation. Impacts on landscape and visual amenity. Requires consideration of heritage and cultural values. Longer timeframe to build and fill than the proposal. Higher cost than the proposal. Damming of an unregulated river. Flooding impact on the endangered Yellow Box woodlands. Impacts in aquatic and terrestrial ecology. Greenhouse gas emissions associated with construction and operation of the reservoir Tantangara Transfer This option was initially evaluated under the Future Water Options project (ACTEW, 2005d) and has been further developed since then. In light of the recent changes to national water management, this option appears to be more promising than when it was when last considered by ACTEW in 2004/2005. The Tantangara Transfer involves the following main actions: Purchasing water from irrigators downstream of the ACT. Storing purchased water in Tantangara Reservoir. Transporting that water from Tantangara to the ACT (Most likely run of river transfer along the Murrumbidgee River). There are some considerable uncertainties with this option that remain unresolved including: ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

75 Having a Murray Darling Basin Water Cap agreed for the ACT. Altering the Snowy Hydro s operating licence. Protracted negotiations with other parties (including licence owners, Snowy Hydro and the NSW and Commonwealth Governments). The cost to purchase water was estimated to be approximately $38 million. Operating costs will be a function of negotiations with Snowy Hydro and others. In accordance with the ACT Government directive, work is progressing on this option. A summary of the performance of the Tantangara Transfer against the principles of Triple Bottom Line is provided in the following table. Table 5.5 Tantangara Transfer summary of performance. TBL Category Performance of option Social Economic Environment Positive community sentiment due to diversification. Requires changing Snowy Hydro s operating license. Requires inter-jurisdictional approvals. Requires negotiations with owners of water entitlements. May require re-assessment of catchment activities and appropriate management practices. Risk to ACT water quality as contamination events upstream may occur without notification to ACTEW. Potential for protracted negotiations. Potential for changes to the recreational facilities available at Angle Crossing. Cost effective. Improves use of the Googong Reservoir. Evaporative and other losses through run of river delivery. Comparatively low environmental impact as no new reservoir will be necessary to store water. Requires installation of pumping infrastructure on the Murrumbidgee River and piping to transfer water to Googong Reservoir. Greenhouse gas emissions associated with pumping Angle Crossing option (Murrumbidgee to Googong) The Angle Crossing option was a primary recommendation of Future Water Options in 2005 (ACTEW, 2005b). The scheme involves the installation of a weir and pumps in the Murrumbidgee River at or near Angle Crossing at the southern border of the ACT. Water would be pumped, via a pipeline, from Angle Crossing, under the Monaro Highway to Burra, before being discharged into Burra Creek. The recent agreement for a regional approach to water management has helped in obtaining better regional support for this option. A summary of the performance of the Angle Crossing option against the principles of Triple Bottom Line is provided in the following table. 68 WATER SECURITY MAJOR PROJECTS AUGUST 2009

76 Table 5.6 Angle Crossing option (Murrumbidgee to Googong) summary of performance. TBL category Social Economic Environment Performance of option Provides additional diversification. Requires inter-jurisdictional approvals. Requires negotiations with land owners. Disturbance to community during construction, particularly road users, local residents and landholders. Changes to local environment including noise levels and visual amenity. Potential for changes to the recreational facilities available at Angle Crossing. Improved use of Googong reservoir. Quick to implement. Extraction only permitted when there is sufficient flow in the Murrumbidgee River. Comparatively low environmental impact as no new reservoir will be necessary to store water. Impacts on Murrumbidgee River through the installation of pumping infrastructure Seawater source Desalination of seawater to serve Canberra and Queanbeyan was also considered as a potential water source for the ACT as part of the Future Water Options assessment (ACTEW, 2004a). This option would consist of: A seawater reverse osmosis process plant located on approximately 35ha on the NSW south coast. The intake and outlet would be located in water depths of approximately 20m offshore to optimise dispersion and intake water quality. The plant would have a capacity of 50 ML/d. A one pass reverse osmosis process would be required if the water is to be delivered to the Queanbeyan River. A two pass reverse osmosis process would be required if the water is to be delivered directly to the existing water supply network so as to match existing water quality. The intake would draw approximately 140 ML/d to produce 50 ML/d of potable water. Reject water would be discharged to the ocean as is the case with similar plants in Sydney and Perth. A 750 (millimetre) mm diameter pipeline approximately 100km long, located within road reserves wherever possible, would connect the plant with the existing supply system. There would be a main pump station at the plant site and three (3) more along the route. Electricity would be sourced from the grid. The proposal would need to be assessed under the NSW Environmental Planning and Assessment Act A 2.5 year to three year timeframe would be required to gain approval, construct and commission the plant (ActewAGL, 2007a). This option is not considered appropriate at this point in time, mainly with regards to the potential complexity in obtaining approval to construct a proposal of this scale as well as the estimated cost for construction and operation (ActewAGL, 2007a). A summary of the performance of desalination of seawater against the principles of Triple Bottom Line is provided in the following table. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

77 Table 5.7 Seawater source summary of performance. TBL category Performance option Social Economic Environment Proven technology. Inter-jurisdictional approvals. Rainfall independent and therefore more reliable and consistent supply. Positive community sentiment due to diversification Higher construction and operating costs. Higher energy use and greenhouse gas emissions due to treatment processes and pumping uphill from the coast to the ACT. May impact aquatic and terrestrial ecology during both construction and operation. Requires disposal of salt brine. Installation of approximately 100km of piping infrastructure Groundwater Groundwater, in the ACT and surrounding NSW, was examined in the Future Water Options studies and is still not considered a viable option. Groundwater can provide benefits on a small localised scale and is already being extracted and used at various locations in the ACT. More detail on the consideration of the groundwater option is available from the report Options for the Next ACT Water Source (ACTEW, 2004a). A summary of the performance of groundwater use against the principles of Triple Bottom Line is provided in the following table. Table 5.8 Groundwater summary of performance. TBL category Performance of option Social Economic Environment Positive community sentiment due to diversification. Risk of contamination due to surrounding land use practices. No large aquifers in or near the ACT. Transfer costs to the ACT network. Greenhouse gas emissions associated with extraction and pumping to the ACT. Depending on location, may impact aquatic or terrestrial ecology. Extraction may not be sustainable Water Purification Scheme ACTEW is investigating adoption of existing (advanced) technology to treat used water (waste water) to a standard that is safe for human consumption. Membrane filtration and reverse osmosis is the preferred combination of treatment processes that provides a multi-barrier approach to water purification. Membrane filtration uses hollow fibre membranes with fine pores to filter particles and micro-organisms. The membrane surface acts like a screen to retain the microorganisms; similar to a screen door that retains insects. This step removes microscopic particles, contaminants and pathogens. Reverse osmosis is the process of pushing water through a membrane or filter that traps almost all suspended and dissolved substances and micro-organisms to one side and allows water to come out the other side. The membranes have very small pores, small enough to trap more than 99 per cent of sodium and chloride ions. This step removes pollutants such as salts, organic compounds and viruses. 70 WATER SECURITY MAJOR PROJECTS AUGUST 2009

78 A further process under consideration (as part of a multi barrier approach) is the inclusion of ultra violet disinfection and advanced oxidation. Ultra violet light is used to disinfect water. UV light is effective at destroying micro-organisms such as Giardia and Cryptosporidium and other pathogens. Oxidation is effective in destroying chemical compounds. Strong oxidation agents such as hydrogen peroxide are commonly used to remove trace organic constituents. This proposal could also take advantage of natural water treatment processes by letting the purified water flow into the natural environment (wetland). A summary of the performance of water purification against the principles of Triple Bottom Line is provided in the following table. Table 5.9 Water purification scheme summary of performance. TBL category Social Economic Environment Performance of option Proven technology. Requires community understanding and support. Higher cost. May not be used in wetter periods. Less dependent on rainfall than a reservoir. Would assist in avoiding restrictions under extremely dry conditions in the future. Creates local employment opportunities. Constructed in area already impacted by the Lower Molonglo Water Quality Control Centre. Higher energy use. Greenhouse gas emissions associated with treatment and supply Stormwater use Stormwater harvesting is promoted in the ACT Government s Think water, act water strategy, as it can assist towards meeting the 25 per cent target reduction of drinking water consumption per person by It is also factored into the ACT Government s Waterways: Water Sensitive Urban Design General Code (2008b) that targets a 40 per cent reduction in drinking water use for all new developments and re-developments. The ACT Government carries out stormwater harvesting from most urban ponds and lakes for use on community parks and ovals. Golf courses, nurseries and other large water users also use stormwater. The ACT Government is currently undertaking the Canberra Integrated Urban Waterways Project with assistance from the Australian Government Water Fund. This proposal will implement stormwater storage, harvesting and use up to three GL/yr by 2015 as well as providing stormwater improvement benefits. A feasibility study is currently underway to determine what level of use is feasible. The proposal will cost $ 17 million (excluding ongoing operation, maintenance and monitoring costs). It is expected that the use of storm water will assist in the management of demand for potable water, but will not provide a secure future water supply. A summary of the performance of stormwater use against the principles of Triple Bottom Line is provided in the following table. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

79 Table 5.10 Stormwater use summary of performance. TBL category Performance of option Social Economic Environment Poor water quality. Large storages required. Provide water for the maintenance of recreational facilities including sports grounds, parks and ovals and other beneficial uses. Potential for positive impacts on landscape and visual amenity. Local use of existing storages can be cost effective. The most cost effective systems are already implemented. Highly variable quantities. Creates local employment opportunities. Provides some stormwater control. May impact aquatic or terrestrial ecology Rainwater collection (private tanks) Rainwater tanks can store runoff from the roof for garden watering and other household uses, contributing towards reducing the residential water demand and serving as a water conservation measure. The ACT Government s Rainwater tanks: Guidelines for residential properties in Canberra (2008c) provides information on this subject. Rainwater tanks are promoted in the ACT Government s Think water, act water strategy, as they can assist towards meeting the 25 per cent target reduction of drinking water consumption per person by The strategy recognises the benefits of installing a rainwater tank in terms of water saving and stormwater reduction. The effectiveness of a tank is increased when the water is used for internal purposes such as toilet flushing, clothes washing as well as garden watering effectively providing a way for the tank water to replace drinking water all year round. The ACT Government has provided household rebates for the installation of rainwater tanks to assist the community contribute to water conservation. To be eligible for a rainwater tank rebate, the tank must be plumbed for some internal use, for example to the laundry or toilet. The use of rainwater tanks is also promoted in the ACT Government s Waterways: Water Sensitive Urban Design General Code (2008b). It is estimated that the cost for installing a tank in all households in the ACT would be approximately $ 330 to $ 550 million and deliver approximately eight GL/yr. Rainwater tanks are also dependent on rainfall thereby reducing the benefit of rainwater tanks during drought periods. There is limited opportunity for citywide rainwater tank use at levels above what is already being put in place. Although rainwater tanks are dependent on rainfall and they can be expensive to install they represent a means to reduce dependence on mains water. The assessment found this option to be a costly solution that would not translate into the storage required to secure the ACT s future water needs. At best this could be a supporting solution but is not a preferred option for future water supply. A summary of the performance of rainwater collection against the principles of Triple Bottom Line is provided in the following table. 72 WATER SECURITY MAJOR PROJECTS AUGUST 2009

80 Table 5.11 Rainwater collection (private tanks) summary of performance. TBL category Social Economic Environment Performance of option Supplement existing drinking water use. Poses a risk to public health if appropriate management is not adopted. Can be used safely in toilets and laundry. Higher cost. Creates local employment opportunities. Rainfall dependent. Difficult to obtain large enough storage. Reduces stormwater runoff Grey water use Grey water is wastewater from hand basins, showers, spas, washing machines, laundries, (but not from the toilet or urinal which is black water). The use of grey water varies from bucketing or siphoning, connecting the outlet drain to a diversion pipe or installing an appropriate grey water treatment system. Grey water use is promoted in the ACT Government s Think water, act water strategy, which includes a target to increase reclaimed water from five to 20 per cent by The strategy is continuing to investigate ways to encourage the take-up of grey water use with consideration being given to incentives and rebate schemes. It is also promoted in the ACT Government s Waterways: water sensitive urban design general code (2008b). Grey water use can replace some drinking water use and contributes to water conservation measures. In addition, it also reduces wastewater flows, which reduces treatment costs and discharge volumes to waterways. Due to poor water quality however, untreated grey water should only be used for irrigation and cannot be stored for more than 24 hours unless an appropriate treatment system is used (ACT Government, 2007d). While grey water use may assist in reducing the demand for potable water, it is not a preferred option for large scale augmentation future water supply. A summary of the performance of grey water use against the principles of Triple Bottom Line is provided in the following table. Table 5.12 Grey water use summary of performance. TBL category Social Economic Environment Performance of option Care needed in handling due to potential health issues. Replaces use of potable water on gardens. Higher cost Ongoing maintenance. Reliability of supply based on household water use practices. Creates local employment opportunities. Reduces sewerage flows (and treatment costs). ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

81 Other non potable reuse options large scale irrigation Non-potable reuse options involve the extension of the existing ACT water reuse schemes for irrigation purposes. This provides additional reuse of water for irrigation of open spaces, parks, ovals and golf courses through Central Canberra, Belconnen, Woden and Tuggeranong and effectively reducing the use of potable water for these uses by approximately three GL/yr. This proposal will require a capital cost of more than $ 100 million. Additional capacity beyond this extension becomes even more expensive. To implement this proposal, approximately 100km of new pipelines will need to be constructed through largely existing urban areas. It also requires several pumping stations to be constructed and connection to decommissioned reservoirs. The demand for non-potable reuse is mostly limited to seasonal demand during warm and dry periods. It has the advantage of allowing use of sports ovals through periods of drought, but does not reduce the probability that severe restrictions will be required for larger Canberra, particularly in current and future droughts. The scheme could only be implemented in some parts of the city, resulting in a potential inequitable distribution of the resource, with some areas benefitting by having access to playing fields during drought whereas other areas of the city would not. This scheme provides only limited additional flexibility to the water supply system, as it provides non-potable water to limited areas of Canberra only through the summer months. It does not supplement the drinking water supply during years with low inflows to reservoirs (like 2006) and only provides limited offsets to the drinking water supply during periods of water restrictions. ACTEW continues to examine ways to further expand non-potable reuse where it is viable, including assessment of storage options, seeking suitable winter demand and water pricing. A summary of the performance of non potable reuse against the principles of Triple Bottom Line is provided in the following table. Table 5.13 Other non-potable reuse options (large scale irrigation) summary of performance. TBL Category Social Economic Environment Performance of proposal Disturbance during installation of infrastructure. Provides water for the maintenance of recreational facilities including sports grounds, parks and ovals. Potential for positive impacts on landscape and visual amenity. Raises issues of equity of access to suitable recreational opportunities. Higher cost. Reliable non potable supply. Creates local employment opportunities. Seasonal use of water. Could potentially maintain or provide habitat for aquatic or terrestrial ecology Accelerated demand management This option requires implementing activities to build on the current ACT Government s demand management (water conservation) program and target a 20 per cent per capita water consumption reduction by 2011, rather than the government s proposed target of 25 per cent reduction by This will involve increased technical assistance and financial incentives to: Adopt low-flow showerheads, dual flush toilets, internal water audits, water-efficient gardens and leak minimisation. Ensure commercial and business establishments use water efficiently and minimise leaks. To install rainwater tanks and grey water recycling systems. 74 WATER SECURITY MAJOR PROJECTS AUGUST 2009

82 Some proposed demand management measures of the Government s 25 per cent reduction are planned for new houses yet to be built, or involve new appliances not yet readily available (Institute for Sustainable Futures, 2003). As these features cannot be brought forward to any significant extent, the full 25 per cent demand reduction may not be achievable by 2011 and ACTEW only considered this option able to deliver a 20 per cent reduction. The outcomes of the analysis of this option indicate a short term advantage with no long term impact on future demand. The cost of this option is approximately $ 150 million. The ranking of this option compared to others indicates this is not a preferred option to provide necessary water security (ActewAGL, 2007a). A summary of the performance of accelerated demand management against the principles of Triple Bottom Line is provided in the following table. Table 5.14 Accelerated demand management summary of performance. TBL category Social Economic Environment Performance of option More efficient use of water. Fast tracks ACT Government s existing program. Benefits current drought situation. Requires considerable community support. No additional long term benefit. Creates local employment opportunities. Low environmental impact Cloud seeding Cloud seeding is a form of weather modification which changes the amount or type of precipitation that falls by dispersing substances into clouds to serve as cloud condensation or ice nuclei. The usual intent is to increase precipitation, but hail suppression is also commonly practiced with these methods. Silver Iodide and dry ice are the most commonly used substances in cloud seeding. Seeding requires clouds to contain liquid water colder than zero degrees Celsius. The introduction of a substance such as Silver Iodide, which has a crystalline structure similar to that of ice, then induces freezing and promotes precipitation. Clouds can be seeded from the air or ground level. Snowy Hydro Limited embarked on a six (6) year research project of winter cloud seeding to assess the feasibility of increasing snow precipitation in the Snowy Mountains. As there have been no cloud seeding studies in the Canberra region, preliminary investigations of seeding types and frequency of suitable atmospheric conditions are required, followed by a four (4) to six (6) year experiment. The correct cloud formations are required for cloud seeding to be successful, therefore research into the types and abundance of clouds over the Canberra water catchment areas needs to be undertaken to determine the usefulness of cloud seeding in the region. ACTEW, ActewAGL and Snowy Hydro Limited are cooperating to understand the potential of cloud seeding for the ACT. A proposal is being developed that builds on the expertise that Snowy Hydro Limited has obtained in the cloud seeding operations to assist with meteorological research into the appropriateness of cloud seeding for the ACT. While cloud seeding has been shown to be effective in altering cloud structure and size and converting cloud water to ice particles, it is more controversial whether cloud seeding increases the amount of precipitation at the ground. This is partly problematic given the difficulty associated with discerning how much precipitation would have occurred had cloud seeding not take place. Nevertheless, there is more credible scientific evidence for the effectiveness of winter cloud seeding over mountains (to produce snow) than there is for seeding warm-season cumuliform (convective) clouds. Cloud seeding essentially makes the wet times wetter and has minimal benefits in dry times. Benefits of cloud seeding will generally only become tangible over a ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

83 long term period, following a trial period to assess effectiveness. On this basis cloud seeding was ruled out as a reliable future water source for the ACT. A summary of the performance of cloud seeding against the principles of Triple Bottom Line is provided in the following table. Table 5.15 Cloud seeding summary of performance. TBL category Performance of option Social Economic Environment Negative community sentiment arising from uncertainty of water supply. Unproven technology. Reliability is not guaranteed, may increase rainfall or may not. Requires ongoing research by ACTEW, a process which may take several years. Impacts on natural rainfall patterns and distribution Watermining TM Watermining TM is a process by which wastewater is taken from a sewer system and treated for reuse in the local vicinity, such as for irrigating ovals, parks and playing fields. ACTEW currently operates a Watermining TM scheme at Southwell Park (Lyneham, ACT), supplying irrigation water for the adjacent Southwell Park playing fields. The plant was commissioned in 1995 as a demonstration facility of new technology. In 2005, ACTEW investigated localised Watermining TM opportunities for the ACT including Watermining TM schemes in areas including Kambah, Stirling, Isabella Plains, Condor, Melba and Charnwood. Investigations highlighted that wastewater harvesting and reuse schemes were expensive and even if maximised across the ACT at a localised scale, would provide little benefit to the overall security of the ACT water supply. Although Watermining TM may have opportunities to benefit individual sites in the ACT, it does not have the potential to provide sufficient water at a reasonable cost to meet the security required for current and future droughts ACTEW continues investigations into the opportunities and constraints for individual sites proposed for additional wastewater harvesting and reuse facilities within the ACT. These investigations consider smaller scale plants than previously considered. A summary of the performance of Watermining TM against the principles of Triple Bottom Line is provided in the following table. 76 WATER SECURITY MAJOR PROJECTS AUGUST 2009

84 Table 5.16 Watermining TM summary of performance. TBL category Social Economic Environment Performance of option Reduces drinking water demand. Further locations being investigated. Provides water for the maintenance of recreational facilities including sports grounds, parks and ovals. Potential for positive impacts on landscape and visual amenity. Raises issues of equity of access to suitable recreational opportunities. Higher cost. Seasonal use. Not a major supply option. Creates local employment opportunities. Greenhouse gas emissions associated with construction and operation infrastructure Evaporation control on reservoirs ACTEW also investigated techniques for reducing evaporation from existing water supply reservoirs. None of the options examined provided a cost effective solution. The options were only suitable for the smaller reservoirs, Bendora and Cotter, which have relatively insignificant evaporation losses compared to Googong and Corin reservoirs and will not provide any significant increase to the ACT s water security if implemented. ACTEW will continue to review new products and techniques that become available. A summary of the performance of evaporation control on reservoirs against the principles of Triple Bottom Line is provided in the following table. Table 5.17 Evaporation control on reservoirs summary of performance. TBL category Social Economic Environment Performance of option Impacts the visual amenity of reservoirs. Does not provide any additional supply. Not cost effective. May impact aquatic ecology. 5.4 Cost benefit analysis In addition to Triple Bottom Line, a cost benefit analysis of available options was undertaken, with ongoing assessment since Future Water Options in Assessment methodology compared the value of increased water security that results from new water storage and supply options against the cost of providing the new water source (ACTEW, 2007c). The net economic benefit of implementing each Future Water Options scenario was calculated by deducting the capital and operating costs of each supply option from the gross economic benefit to the community from greater water security and less time spent in drought restrictions. Assessment considered the benefit of options under modelled future climate conditions, simulated by extending 133 years of observed weather by standard hydrological process and adjusted to account for the CSIRO s most pessimistic climate projection for the ACT in the year ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

85 5.5 ACT Government decision major water security initiatives In October 2007, following from the ACTEW Water Security recommendations (ACTEW, 2007a), the ACT Government announced a range of initiatives that will be implemented to secure Canberra and the region s water supply into the future and unlock the potential to provide water through extended drought periods. The proposals endorsed by the ACT Government include: The enlargement of the Cotter Reservoir (this proposal) from four GL to 78GL, with planning and design work to begin immediately and work expected to be completed within three (3) to five (5) years. The installation of infrastructure to increase the volume of water transferred from the Murrumbidgee River to the Googong Reservoir. The design of a demonstration water purification plant, with the water produced during demonstration to be used for purposes other than drinking (ACT Government Press Release, October 2007). These represent the preferred options for the ACT, satisfying the key planning assumptions, Triple Bottom Line and cost benefit assessments. 78 WATER SECURITY MAJOR PROJECTS AUGUST 2009

86 6 Description of the proposal This chapter provides details on the design, construction and inundation/ operation and decommissioning phases of the proposal as relevant to the assessment of impacts on the listed threatened species. It also includes a detailed assessment of the short and long term, and down and upstream changes in water flows due to the proposal. 6.1 General description The enlarged Cotter Reservoir proposal consists of a main dam located on the Cotter River, approximately 125m downstream of the existing Cotter Reservoir, in the Lower Cotter catchment, with two (2) saddle dams to the right abutment facing downstream and associated engineering infrastructure. The regional context of the proposal was provided in Figure 3.1. The main dam wall will be approximately 80m high with an associated full supply level of approximately 550m AHD. The two (2) saddle dams will be built to an approximate height of 12m and 16m, respectively. The main dam wall will be constructed of RCC, with some engineering components constructed from conventional concrete, and the saddle dams will to be constructed of earth/rock fill with a clay core (ACTEW, 2009a). 6.2 Scope of works The proposal includes the design, construction, and the inundation/operation of the main reservoir and associated engineering infrastructure, including site establishment and the decommissioning of the existing Cotter Reservoir. The scope of works associated with the proposal include: Detailed geotechnical investigation for all works (including main infrastructure, quarry and borrow areas). Design and construction of the main dam, intake structure, spillway and the saddle dams. Design and construction of protection works (flood diversion around site works during construction). Design and construction of dam outlet works, including flow control valves, control instrumentation and gauging. Site establishment of temporary structures used during construction, including site compounds, ablution facilities, quarry, clay borrow areas, batching and crushing plants, and fencing. Design and construction of upgrade works required for site access routes, haul roads and forestry tracks. Design and installation of a system to mix the water in the reservoir to maintain water quality. Investigation, design and installation of power supply and communications infrastructure (likely to be wireless) to service construction and ongoing operational requirements. Development and implementation of a community and stakeholder engagement program and provision of community education and visitors services. Implementation of the ECD Fish Management Plan, which includes ecological studies and artificial habitat design and construction. Decommissioning of the existing Cotter Reservoir. Rehabilitation and revegetation following construction activities. The design, construction and inundation/operation of the proposal are described in the following sections. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

87 6.3 Design The design is based on environmental conditions, planning issues, technical matters such as geology, and ongoing operational requirements for the future reservoir. The design of the dam structure and outlet works will take into account the natural and physical values of the surrounding area, the appearance of the dam and its integration into the local Cotter recreational area. Design will also address the possible progressive impoundment of water during construction and ensure the ability to meet ongoing abstraction licence conditions, operational requirements associated with the existing reservoir being part of Canberra s water supply system and mandated environmental flows. The design process will involve the following key aspects: Undertaking hydraulic modelling of dam and spillway and assessment in line with Australian National Committee on Large Dams (ANCOLD) guidelines. Revising existing geotechnical investigations and defining the scope for additional investigations (including dam site, foundation grouting, quarry, saddle dams, access roads). Assessing potential quarry materials and carry out physical and chemical analysis together with crushing trials and preliminary RCC mix designs. Assessing the extent of foundation grouting and stabilisation requirements. Assessing main and saddle dam arrangement options for primary and/or auxiliary spillways. Developing internal drainage design (optimise the number and location of galleries, determine ventilation, lighting and operational requirements). Undertaking dam stability analysis in line with ANCOLD guidelines for normal, unusual and extreme load conditions using international guidelines on dam stability criteria (Canadian Dam Association, 2007; Federal Energy Regulatory Commission, 2002; United States Army Corps of Engineers 1995, 2000 and 2005; United States Department of the Interior, Bureau of Reclamation, 1987). Developing diversion solutions (including flood risk control, materials, closure structure). Developing coffer dam designs (upstream and downstream coffer dams) including location, geometry, height and materials. Reviewing options for fish-friendly design and construction of the main dam and coffer dam. Developing outlet tower and outlet works designs including mechanical, electrical and control. Developing a control and monitoring system for outlet. Developing solutions for access road and public viewing facilities. Developing a revised dam safety plan for the existing Cotter Reservoir during construction. Developing a dam safety plan for the new dam while under construction and once commissioned. Undertaking hydraulic design for pipe work and pumping infrastructure. Developing a decommissioning plan for the existing Cotter Reservoir, obsolete pipe work and pumping infrastructure. On completion, the design will be reviewed by ACTPLA, the technical regulator of utilities in the ACT, to ensure the safety of the structure, infrastructure and the community and to ensure compliance with relevant legislation, technical standards and codes. Once approved, the design will be implemented in accordance with any stipulated conditions and ACTEW s commitment to sound, ongoing management and monitoring procedures. 80 WATER SECURITY MAJOR PROJECTS AUGUST 2009

88 6.4 Construction Construction is due to commence in September 2009, with site establishment and other preliminary activities undertaken as allowed by the Territory and Commonwealth approvals processes. The construction of the proposed reservoir will be based on detailed designs (due for completion September 2009), which incorporate the findings and recommendations of the PER, EIS and DA processes. Works will include site establishment, the quarrying and stockpiling of dam building material, the preparation of concrete for construction of the dam and all of the peripheral works, placing of RCC and other general construction and maintenance activities Site establishment and layout The proposed site layout during construction activities is provided in Figures 6.1 and 6.2. The key items identified in the figures are: A substantial truck turning area adjacent to the concrete batch plants, for fly ash and cement deliveries. Working stockpiles. The quarries for sourcing local construction material. The crusher pad and material stockpile area, occupying approximately 150m by 200m, at the southern end of the works area. The efficient management of the materials through the site, which takes into account safety issues. The saddle dams which will be constructed prior to the main dam wall. A linear material delivery process starting at the crusher at the southern end of the site, feeding material to the working stockpiles. Material then moving northwards to the concrete batch plants, and from there the concrete mix loaded directly onto conveyor systems to be transported to the dam site for placement Dam construction process The main dam wall will be constructed of RCC, a technique which allows a high rate of concrete placement over a relatively short duration (approximately 12 months), with placement expected to peak at 50,000 cubic metres (m 3 ) per month. In addition to the speed of construction, RCC has the advantage of simplified placement procedures and can be undertaken 24 hours per day using the process shown in Figure 6.3 (ACTEW, 2009a). Both RCC and conventional concrete (used for other engineering components) will be produced from the onsite batch plant using aggregate sourced from the onsite quarry and other materials sourced offsite as necessary Associated works and onsite materials Works associated with construction activities for the establishment of the main engineering works, as described above, constitute the following: Establishment of a rock quarry for the winning of sand and aggregates for use in construction of the dam, saddle dams and other associated works. Establishment of materials borrow areas (primarily clay). Bulk earthworks for the construction of pads for construction lay down areas, permanent materials stockpiles on both northern and southern abutments, batching, crushing operations and preparation of the construction site for placement of the main dam and associated infrastructure. Upgrades of the intersections of Settlement Road and Paddy s River Road as well as Brindabella Road and Look-out Road. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

89 Rock quarry and materials borrow areas ACTEW has investigated and identified the location of a rock quarry and three (3) clay borrow areas (located predominantly under the full supply level (FSL) of the proposal) to be used to win onsite materials for construction of the main dam and saddle dams. The location of the quarry has been based on physical and chemical testing of rock and extensive geotechnical investigations. Appropriate design will ensure that the quarry will generally be below the FSL of the proposal. In construction of the saddle dams, material is required to create a waterproof core of approximately 50,000 m 3 of clay. Three (3) materials borrow areas have been identified (refer Figure 6.2) and preliminary investigations suggest these locations will yield suitable clay for creating the cores. Clay and other useful materials gained will be stockpiled within the construction area (adjacent to the proposed saddle dams) and treated/processed prior to being placed in the saddle dams. Treatment of clay material may involve drying out gained material and addition of a benign material such as lime or bentonite to improve the impermeability of the materials. Bulk earthworks construction site preparation (construction pads and haul roads) Stripping of the overburden at the main dam and saddle dam sites, quarry and main haul roads is estimated to produce approximately 500,000 m 3 of spoil. The different types and grades of material obtained from the stripping activities will be used for various applications within the construction site. Beneficial reuse options include the reuse of materials as aggregates in the construction of the engineering infrastructure (still being investigated), creation of construction pads to house construction activities, sediment/erosion protection structures and the like. Road intersection upgrades Both Settlement Road and Paddy s River Road will be upgraded to allow safe efficient access to the proposed construction area. Signage, fencing and lighting During construction, a number of temporary signs will be displayed to provide information on construction activities. These signs will not be illuminated and will be removed once construction in completed. Temporary and permanent fencing will be utilised to cordon off areas during construction and the operation of the proposal. Temporary lighting will be installed for use in areas during night time works for construction. Rehabilitation works All areas disturbed by activities during the construction of the proposal will be progressively rehabilitated following construction activities. Rehabilitation activities in relation to listed species are discussed in Section WATER SECURITY MAJOR PROJECTS AUGUST 2009

90 Figure 6.1 Concept diagram of the main engineering infrastructure and construction area. ENLARGEMENT OF THE COTTER RESERVO R AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

91 Figure 6.2 Indicative construction area at clay borrow sites. 84 WATER SECURITY MAJOR PROJECTS AUGUST 2009

92 Figure 6.3 Construction cycle for the main dam proposed RCC construction process. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

93 Figure 6.4 Concept diagram of the delivery of RCC to the dam conveyor (swinger) layout Plant and equipment The plant and equipment to be used for the construction of the main dam wall, saddle dam walls, access roads and the establishment of the quarry and clay borrow areas will include: Tracked dozers from D5 size through to D10. Front-end loaders, possibly four (4) or five (5), on aggregate stockpiling and storage. At least seven (7) off-highway trucks such as Caterpillar 769 or all terrain 35-tonne class to be used on both foundation excavation and RCC placement. Site concrete batching plants to produce the RCC, including a twin nine (9) cubic metre tilt drum mixer, possibly augmented by an additional smaller wet batch plant. A separate dry mix batch plant for site-batched concrete. The plant and equipment will be supported by a fully resourced on-site maintenance workshop with fuel storage, boilermaker facilities and personnel able to carry out hydraulic and electrical repairs. 86 WATER SECURITY MAJOR PROJECTS AUGUST 2009

94 Figure 6.5 Concept diagram of the layout of the tower crane (and showing spans over the proposed main dam wall). ENLARGEMENT OF THE COTTER RESERVO R AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

95 6.4.5 Potential impacts The construction of the dam wall and saddle dams and other associated ancillary activities will have an immediate, direct impact on native and non-native vegetation. Table 6.1 provides a summary of the vegetation that will be impacted by the proposal (Biosis Research, 2009b). Table 6.1 Estimated vegetation type and loss due to actions relating to the construction of the main dam wall and ancillary structures. Vegetation structure Area native vegetation (ha) Non-native vegetation (ha) Acacia Shrubland old pine plantation/wildings Eucalyptus macrorhynca dry woodland Casuarina cunninghamiana riparian woodland. 0.6 Former pine forest and exotic shrubland Total (ha) The potential impacts of the construction of the proposal on listed threatened terrestrial species and proposed mitigation measures and monitoring are detailed in Chapter Inundation Based on current modelling of rainfall events it is anticipated that it will take approximately 2 6 years for the reservoir to fill to the 78GL (ACTEW, 2009a). The loss of upstream riparian and gorge vegetation will be gradual and contingent upon the rate of inflow, but once the reservoir reaches full capacity its horizontal footprint will increase from its current 44.2ha to approximately 283ha (shown in Figure 6.6). This increase will inundate an estimated 92.5ha of moderate to good quality native vegetation when full. In addition, some 139ha of former pine plantation in various stages of regeneration would also be inundated by the proposal. Table 6.2 provides a summary of vegetation lost through inundation. 88 WATER SECURITY MAJOR PROJECTS AUGUST 2009

96 Figure 6.6 Comparison of the existing and proposed Cotter Reservoir inundation areas. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

97 Table 6.2 Estimated total vegetation loss at maximum reservoir capacity. Community Native and exotic vegetation (ha) Eucalyptus macrorhynca dry woodland Acacia riparian scrubland Acacia shrubland. 0.8 Eucalyptus viminalis riparian forest. 4.0 Casuarina cunninghamiana riparian woodland. 2.6 Callitris endlicheri woodland. 1.0 Reedland (Eleocharis, Phragmites and Typha). 3.3 Former pine forest and exotic shrubland Total (ha) Despite severe fire damage, the loss of 92.5ha of moderate to good quality native vegetation and the inundation of extensive rocky gorge habitat were considered substantial losses of mostly moderate to good quality native vegetation and a wide range of good quality terrestrial habitats. The potential impacts of inundation on listed threatened species and mitigation measures and monitoring are discussed in Chapters 7 and 8 for terrestrial and aquatic species, respectively. 6.6 Operation The new reservoir will become an active reservoir characterised by fluctuating water levels, more frequent abstraction of water and a greater capacity to capture additional inflows from the upper Cotter River. There will be two (2) key environmental issues that relate to the ongoing operation of the proposal: The management of the habitat of threatened aquatic species. The release of flows downstream of the reservoir (and the impact on threatened aquatic species and their habitats) Management of the habitat of threatened aquatic species The operating rules for the proposal will be designed to ensure the enlarged reservoir continues to support threatened aquatic species, including the management and monitoring of habitat (natural and artificial). This will also include ensuring there is sufficient water in the reservoir to allow access to artificial habitats and preventing barriers to fish movement during spawning migration to sections of the Cotter River upstream of the proposed reservoir Downstream flow releases Although the proposal will spill less frequently than the existing reservoir, it will allow increased environmental flows releases during drought conditions when water restrictions are necessary. The environmental flows which ACTEW is required to release for each of its water supply reservoirs are specified in the Environmental Flow Guidelines (ACT Government, 2006) and are enforced under the Water Resource ACT 1998 through the licence granted to ACTEW. The Guidelines have been developed using up to date scientific information and are designed to mimic natural river flows by identifying the essential features of the flow regime, including variability, seasonal variation, floods and intermittent dry periods (ACT Government 2006). The objective of the Guidelines is to achieve a balance between ensuring adequate supply for human consumption and protecting the health of 90 WATER SECURITY MAJOR PROJECTS AUGUST 2009

98 aquatic ecosystems. Under the current system, if water restrictions limiting the amount of water used by the community are in place, due to drought conditions and low storage volumes, the Guidelines specify special rules that permit the reduction of environmental flow releases. A larger reservoir will increase the available water supply and therefore reduce the time spent in water restrictions during drought conditions, meaning more environmental flows must be released to meet the normal requirements of the Environmental Flow Guidelines The modelled changes to downstream water flows are discussed in detail in Section 6.8. The potential impacts of the operation of the proposal on listed threatened species and mitigation measures and monitoring are discussed in Chapters 7 and 8 for terrestrial and aquatic species, respectively. 6.7 Decommissioning The enlarged Cotter Reservoir and associated water supply infrastructure will be designed for a life of at least 100 years. It is common practice that the operating components of the infrastructure (valves, pipes and the like) will require maintenance and will be upgraded over the lifetime of the reservoir. It is not considered that the reservoir itself be decommissioned and demolished at any time in the future. The maintenance and upgrading of dam components will be undertaken as required and environmental and planning approvals obtained during that time. The existing Cotter Dam will remain in situ and will be inundated by the new reservoir. To ensure the existing dam will no longer act as a water retention structure, its valves will either be removed or fixed open to permit water to flow through the structure and the tension on wall anchors will be released. At the end of construction activities, the quarry and borrow pit faces (both rock quarry and clay borrow areas) will be left in a safe condition and will be predominantly below the enlarged reservoir full supply level and may provide additional fish habitat. Other disturbed areas will include the rock crusher and storage areas, haul roads, saddle dams and the concrete production area. On completion of the works these areas will be reshaped to provide more natural landforms. The top surfaces will be ripped and planted. A decommissioning plan will be developed as part of the detailed design of the proposal. The plan will detail how the site will be shaped and rehabilitated following completion of construction activities. The intention of the plan will be to develop a site where the landscape post construction blends in with the existing landscape. This plan will detail the procedures for the management of topsoil, terrestrial ecology, post-construction terrain, site facilities and access roads. 6.8 Down stream changes in water flows The following section describes the monthly flows for the last ten years measured between Cotter Reservoir and the junction of the Cotter and Murrumbidgee Rivers. These are then compared against forecasted flows over a 20 year period for the same section of the Cotter River, including the period of time required to fill the Cotter Reservoir. Figure 6.7 shows the monthly total flows from the last ten years, measured at the Cotter Kiosk Gauging Station, on the Cotter River between the existing Cotter Reservoir and the Murrumbidgee River. This includes approximately five (5) years when the Cotter Reservoir was not used for water supply purposes. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

99 Figure 6.7 Monthly total flows downstream of the Cotter Reservoir for January 1999 to January The flows from 2006 onwards show a clear reduction in downstream flow. This can be attributed to drought conditions and an associated reduction in environmental flow requirements and the reinstatement of the Lower Cotter as a water supply source. The flows for this ten year period have an average of 2,700 megalitres per month (ML/month), with 5 per cent of flows equal to or in exceedance of 9,265 ML/month (the fifth percentile) and five per cent of flows equal to or less than 143 ML/month (the 95 th percentile). A percentile is defined as the value which is equalled or exceeded for a given percentage of time. In this case the fifth percentile is the flow rate which is equalled or exceeded 5 per cent of the time. This means the largest 5 per cent of flows are equal to or greater than the value of the 5 th percentile and all other flows are less than this value. The 95 th percentile is the flow rate which is equalled or exceeded 95 per cent of the time. This means 95 per cent of flows are equal to or greater than the value of the 95 th percentile and the lowest 5 per cent of flows are less than this value. Extensive modelling of the ACT water supply both with and without the implementation of the proposal has been conducted. This modelling has taken into account the key planning assumption established by ACTEW. To model the effect of climate change and variability on the ACT water supply, ActewAGL used stochastic data, generated numerically to obey the statistical properties of the historic flow data. Access to a large quantity of stochastic data allows droughts worse than those historically experienced (but that could still be reasonably expected to occur), and their impact on the ACT water supply to be modelled. Modelling of future climatic conditions used stochastic climate data to produce 200 different 48 year daily rainfall and evaporation sequences. These were then used to produce corresponding monthly streamflow sequences using rainfall runoff models and monthly per-capita demand sequences using a demand model, both calibrated to the historic data. 92 WATER SECURITY MAJOR PROJECTS AUGUST 2009

100 The 200 different 48 year streamflow and demand sequences were then modelled with the Resource Allocation Model (REALM) water supply system model, which allocates water from the various sources according to system constraints and operating rules designed to maximise water supply system security. These 200 model runs (also called replicates) were performed with a model representing the existing system, and a model representing the system with the Enlarged Cotter Reservoir. The latter model begins with the existing Cotter Reservoir, and includes the construction and filling time of the proposal. Both models began all of the modelling sequences with the same volumes of water in all of the reservoirs (that which were current at the time of the modelling). Possessing 200 possible outcomes for each month in a 48 year sequence beginning from the present allows the model results to be presented as a probability distribution. This provides a much more robust and realistic method for assessing likely future outcomes than simply reproducing a repeat of the historic climate sequence for the ACT. It is important to note that the analysis only considers the sensitivity to climate variability. While a range of other assumptions such as climate change, population change, demand reduction, yield reduction as a result of bushfires, environmental flow requirements, system operation rules, and the affect of drought restrictions on demand have been included in the modelling, analysis of the sensitivity of the model to variability in these assumptions has not been undertaken. The range of expected flows and the probabilities of these flows occurring over the period 2011 to 2031 downstream of Cotter Reservoir are shown in Figure 6.8. This 20 year period is from when construction of the proposal begins in the model. This does not differentiate between the short term period when the reservoir is filling and the long term operations of the reservoir. Figure 6.8 Downstream of Cotter Reservoir flow duration curve for the existing and proposed reservoirs ( ). ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

101 Figure 6.9 shows a time series of modelled flows for each month for 22 years with the proposal and with the existing Cotter Reservoir. This includes 20 years of comparative date with and without the proposal, and two years where neither scenario includes the proposal ( ). The average modelled results for each month are shown, as well as the 95 th and 5 th percentiles for each month. Percentiles are included to show the probability of high (5 th percentile and above) or low (95 th percentile and below) flows in any month. The lines do not correspond to a particular one of the 200 replicates, but represent statistical information based on all replicates. Figure 6.9 Monthly predicted flows downstream of Cotter Reservoir with and without the proposal. In the long term, Figure 6.9 shows with the proposal there is an increase in the 95 th percentile flows, due to a reduced probability of water restrictions. There is little change in the average or 5 th percentiles in the long term. The magnitude of these changes is quantified in Table 6.3. From January 2011 to January 2013 the average and 95 th percentile flows are lower with the proposal. This is due to the storage capacity of the new reservoir catching flood events and preventing spills while the enlarged reservoir is filling. Table 6.3 shows the change in average, 5 th percentile and 95 th percentile flow predictions for the short and long term. 94 WATER SECURITY MAJOR PROJECTS AUGUST 2009

102 Table 6.3 Short and long term modelled flow projections for downstream Cotter Reservoir. March 2011 to March 2013 With proposal Without proposal Change (% of without proposal) Mean annual flow (ML/yr). 17,400 38, % decrease. Mean flow (ML/month). 1,450 3, % decrease. 5 % flow (ML/month). 6,290 12, % decrease. 95 % flow (ML/month) %. April 2013 to March 2031 Mean annual flow (ML/yr). 35,200 37,830 7 % decrease. Mean flow (ML/month). 2,930 3,150 7 % decrease. 5 % flow (ML/month). 11,900 12,700 6 % decrease. 95 % flow (ML/month) % increase. In the short term, March 2011 to March 2013, there is approximately a 50 per cent reduction in the average and the 5 th percentile predictions. This is due to the new reservoir catching flood events as the reservoir fills. The 95 th percentile flow is not impacted. In the long term, taken as April 2013 to March 2031 the modelling indicates little change to the flows downstream of the Cotter Reservoir. The average is reduced by 7 per cent, the fifth percentile modelled result is reduced by 6 per cent and the 95 th percentile is increased by over 200 per cent, due to increased environmental flows. Figure 6.10 shows the modelled flows at Mt MacDonald, a gauging station on the Murrumbidgee River downstream of the confluence with the Cotter River, with and without the proposal. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

103 Figure 6.10 Flow duration curve for flows in the Murrumbidgee River at Mt MacDonald. Table 6.4 Flow statistics for Murrumbidgee River at Mt MacDonald. With proposal Without proposal Change (% of without proposal) Average flow (ML/yr). 272, , % decrease. Average (ML/month). 22,720 22, % decrease. 95 th percentile (ML/month) % increase. 5 th percentile (ML/month). 73,500 74, % decrease. Figure 6.10 and Table 6.4 indicate that the low flows in the Murrumbidgee River will increase, while high flows will have a small decrease as these flows will be managed by the operation of the new reservoir. Therefore, during operation, the new reservoir will not result in a significant change to flow in the downstream river system. The new reservoir will have the opportunity to provide managed environmental flows downstream into the Cotter and Murrumbidgee Rivers. 96 WATER SECURITY MAJOR PROJECTS AUGUST 2009

104 6.9 Upstream changes in water flow The following section provides monthly flows for the last ten years from a point between Bendora Reservoir and Cotter Reservoir. It then shows the results of forecasting over a 20 year period for the same section, including the period of time required to fill the Cotter Reservoir. Monthly total flows from the last ten years from the downstream Bendora Gauging Station, on the Cotter River between Bendora Reservoir and the Cotter Reservoir, are shown in Figure Figure 6.11 Historical monthly total flows downstream of the Bendora Reservoir for January 1999 to January The historical flows over the last ten years as show in Figure 6.11 have an average of 1,576 ML/month, a 5 th percentile of 5,976 ML/month and a 95 th percentile of 180 ML/month. The period from 2004 onwards shows a marked decrease in the frequency of spills, resulting from drought conditions. Figure 6.12 shows a flow duration curve of modelled releases and spills from Bendora Reservoir with and without the proposal. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

105 Figure 6.12 Flows downstream of the Bendora Reservoir 2011 to With the proposal in place most percentile flows will be slightly higher than without the proposal. During water restrictions the model assumes a reduced requirement for environmental flows. With the proposal there is less time in water restrictions, the water supply is less stressed and the full environmental flow allocation is met more of the time than without the proposal. The highest 10 per cent of modelled flows are of a smaller magnitude with the proposal than without. The pool maintenance flows required as part of the environmental flow regime are always met, however, large spill events in excess of these requirements are smaller with the proposal as under proposed operating rules Corin Reservoir will tend to be operated at a lower level. Figure 6.13 shows a time series of modelled flows downstream of the Bendora Reservoir for each month for 20 years with the proposal and with the existing Cotter Reservoir. The average modelled results for each month are shown, as well as the 95 th and 5 th percentiles for each month. A percentile defines the percentage of modelled results that equal or exceed the given value. These are included to show the probability of high or low flows in any month. 98 WATER SECURITY MAJOR PROJECTS AUGUST 2009

106 Figure 6.13 Monthly Predicted flows downstream of Bendora Reservoir with and without the proposal. Figure 6.13 shows the proposal has only a minor overall effect on the flows downstream of Bendora Reservoir. The most obvious difference with the proposal in place is a reduction in the 5 th percentile flows, consistent with Figure In both the short and the long term, including the period of time to construct and fill the proposal, the average flows with the proposal and without the proposal are similar. Table 6.5 shows the change in average, 5 th percentile and 95 th percentile flow predictions in ML/month for the short and long term downstream of Bendora Reservoir. Table 6.5 Short and long term modelled flow projections for downstream Bendora Reservoir. March 2011 to March 2013 With proposal Without proposal Change (% of without proposal) Mean annual flow (ML/yr). 25,000 25, % decrease. Mean flow (ML/month). 2,080 2, % decrease. 5 % flow (ML/month). 6,610 7, % decrease. 95 % flow (ML/month) %. April 2013 to March 2031 Mean annual flow (ML/yr). 25,700 25, % decrease. Mean flow (ML/month). 2,140 2, % decrease. 5 % flow (ML/month). 6,570 7, % decrease. 95 % flow (ML/month) % decrease. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/

107 6.10 Changes in the management of water resources in the Cotter River system The future potential impacts of the changes in management of water resources in the Cotter River system, in particular, the Bendora Reservoir are to be considered during the construction and operation of the new reservoir. The main issues relate to the change in level of the Bendora Reservoir due to the operation of the new reservoir and cold water pollution released into the reservoir from the upstream Corin Reservoir (and in particular any impacts on listed threatened species, notably the Trout Cod in the Bendora Reservoir). The ACT currently extracts water for the potable water supply from the Cotter River (Cotter, Bendora and Corin Reservoirs) for treatment at the Mount Stromlo Water Treatment Plant prior to supply. Water for potable supply is also extracted from the Googong Reservoir on the Queanbeyan River, with treatment at the Googong Water Treatment Plant and from the Upper Murrumbidgee River by pumping to the Cotter Pump Station, with treatment at the Mount Stromlo Water Treatment Plant. Extraction rules for each of these rivers are regulated by the ACT Government and are based on environmental flows and water quality. In the ACT system the highest quality and least expensive water is sourced from the Corin and Bendora Reservoirs. However, to preserve security of supply, ACTEW continues to extract water for urban use from the Murrumbidgee River, Cotter and Googong Reservoirs. When reservoir levels are high, water is extracted from the higher Corin and Bendora Reservoirs in the Cotter River catchment, and when reservoir levels are low, as experienced over the last eight (8) years, water is extracted from the Murrumbidgee River, Cotter and Googong Reservoirs. If the proposal is constructed ACT storages will be operated in accordance with operating rules developed to maximise water supply performance and meet environmental objectives. These rules are yet to be finalised and will require endorsement by ACTEW before they are adopted. It is also likely that the proposed operating rules will be reviewed by ACTEW up to and after the date that the proposal is operational as new information becomes available. This review may highlight necessary changes to the operation of the water supply systems, independent of the impacts of the proposal. The new operating rules will also need to meet the requirements of the ACT EPA, who issue ACTEW a licence under the ACT Water Resources Act The predicted changes in the operation of Cotter River storages as a result of the proposal are shown in the figures 6.14 and 6.15 below. In addition, water releases from the upstream Corin Reservoir will be sourced from a multi-level off-take tower to ensure the water temperatures (through active insitu regular measurements) correspond to ambient conditions in the downstream Bendora Reservoir and new reservoir (in particular to the management of the Trout Cod population and impacts on their spawning in the Bendora Reservoir). The operating rules applied to the Cotter River water supply sources in the model before and after the proposal are shown in the following figures. The key differences in the operating rules are shown in bold text. The first difference is a check of the total storage of all reservoirs when deciding to use the Cotter Reservoir or not. This is changed from checking if the total storage is less than 70 per cent to checking if the proposed reservoir s percentage storage is greater than 1.45 times the combined percentage storage in Corin, Bendora and Googong Reservoirs. This means for example that if the proposal is full it is only used if the combined storage of Corin, Bendora and Googong is less than 69 per cent. This change is required to define how to use the larger storage of the proposal. The other major difference is that Bendora only has to be used when it is above 76 per cent with the proposal compared to 61 per cent without the proposal. This results in the model showing the end of month storage in Bendora at times being higher with the proposal than without it. 100 WATER SECURITY MAJOR PROJECTS AUGUST 2009

108 Figure 6.14 Operating Rules with the existing Cotter Reservoir. ENLARGEMENT OF THE COTTER RESERVOIR AND ASSOCIATED WORKS PUBLIC ENVIRONMENT REPORT 2008/