Commonwealth environmental water use options : Lower Murray-Darling Region

Transcription

1 Commonwealth environmental water use options : Lower Murray-Darling Region 1

2 Cover image credit: The River Murray, South Australia SA Department of Environment, Water and Natural Resources - used with permission. Acknowledgement of the Traditional Owners of the Murray-Darling Basin The Commonwealth Environmental Water Office respectfully acknowledges the Traditional Owners, their Elders past and present, their Nations of the Murray Darling Basin, and their cultural, social, environmental, spiritual and economic connection to their lands and waters. This report should be cited as Commonwealth environmental water use options : Lower Murray-Darling Region. Published by the Commonwealth Environmental Water Holder for the Australian Government. Commonwealth of Australia This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth. Requests and enquiries concerning reproduction and rights should be addressed to Department of Sustainability, Environment, Water, Populations and Communities, Public Affairs, GPO Box 787 Canberra ACT 2601 or public.affairs@environment.gov.au Information presented in this document may be copied for personal use or published for education purposes, provided that any extracts are fully acknowledged. The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the Australian Government or the Minister for Sustainability, Environment, Water, Population and Communities. While reasonable efforts have been made to ensure that the contents of this publication are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication 2

3 Commonwealth environmental water use options : Lower Murray-Darling Region Table of contents 1. Introduction Context for water use in in the Lower Murray-Darling Region Delivering environmental water to the Lower Murray-Darling Region Operational and management considerations for in the Lower Murray-Darling Region Valley condition Water availability Commonwealth environmental water holdings in the Lower Murray-Darling Region for Other sources of environmental water allocations Natural or unregulated flows and planned environmental water Planning for water use in the Lower Murray-Darling Region in Planning for a range of inflows in Implementing watering actions throughout the year Water use options and the Basin Plan s environmental watering plan objectives Demonstrating how Commonwealth environmental water in will contribute to the Basin Plan s environmental watering plan objectives Lower Murray-Darling Region Water use options for Watering options Assessment of environmental watering options Accounting for the use of Commonwealth environmental water Water use accounting Operational monitoring Partnerships Bibliography

4 List of Figures Figure 1: Map of the Lower Murray-Darling Region... 9 Figure 2: How inflows may vary and impact on water resource availability over the course of in the Lower Murray-Darling Region, from a starting point of Moderate to High resource availability List of Tables Table 1: Operational considerations for the Lower Murray-Darling Region in Table 2: Commonwealth environmental water holdings in the Lower Murray-Darling Region as at 30 April Table 3: Other potential sources of environmental water in the Lower Murray-Darling Region for Table 4: Expected outcomes from the use of Commonwealth environmental water in the Lower Murray-Darling Region Table 5: Summary of water use options for the Lower Marray-Darling Region in

5 1. Introduction This document is designed to be read in conjunction with the Commonwealth environmental water use options : Planning approach, which outlines the approach to planning for the use of Commonwealth environmental water this coming water year. The planning document provides the context for key aspects of the approach including determining resource availability, the expected outcomes from watering actions and the relationship between the function of the Commonwealth Environmental Water Office (the Office) and the Basin Plan. This document outlines watering options for the use of Commonwealth environmental water in the Lower Murray-Darling Region this year. The options, which describe potential watering actions, series of actions, or watering strategies, do not represent a commitment for water use. Consistent with the Office s framework, decisions to make water available for any of the potential options will be subject to an assessment against five published criteria (available from the Office s website) and seasonal, operational and management considerations at the time of the action. All relevant watering actions will be assessed to ensure the best possible use of environmental water within the relevant planning area and across the Murray-Darling Basin and having regard to the Murray-Darling Basin Authority s Basin annual environmental watering priorities, once published. 5

6 2. Context for water use in in the Lower Murray-Darling Region 2.1. Delivering environmental water to the Lower Murray-Darling Region Flows in the Lower Murray-Darling Region are strongly influenced by inflows generated in upstream parts of the Murray-Darling Basin, including the upper River Murray and lower Darling River systems. River flows in the upper Murray River are driven by rainfall events, storage operations and inflows from tributaries such as the Murrumbidgee, Goulburn-Broken, Ovens, Kiewa, Loddon and Campaspe rivers. Rainfall events in the northern basin drive inflows into the Darling River and influence the operation of the Menindee Lakes system; thus affecting inflows to the lower Darling River system and into the lower River Murray. The day-to-day delivery of water (including environmental water) along the main stem of the River Murray is managed by the Murray-Darling Basin Authority s (MDBA) River Murray Operations, in close consultation with state government agencies and state water authorities. The river system is operated by taking into account a range of considerations such as water demand, flow requirements, estimated evaporation, forecast rainfall and water carrying capacity of the river channel at various locations (Murray Darling Basin Authority 2008). River Murray Operations (MDBA) will provide guidance on the delivery of environmental water along the Murray River. The provision of Commonwealth environmental water to the Lower Murray-Darling Region differs depending on which part of the valley that water is being delivered to. Where possible, environmental water will be managed to benefit multiple sites en-route to maximise the efficiency and effectiveness of water use. A description of the mechanisms for environmental water delivery to specific parts of the Lower Murray-Darling Region is set out below. Lower Darling River system The Menindee Lakes are used to deliver environmental water to the lower Darling River system, the Great Darling Anabranch and further downstream into the River Murray. Under regulated conditions the lower Darling River receives flows from the Menindee Lakes Scheme. Releases are made from outlet regulators on Lakes Menindee, Pamamaroo and Wetherell. For each regulator the maximum capacity is in the order of 5,000 ML/day, however this is heavily dependent on water levels in the Lakes. Furthermore, the order of drawdown for the Lakes will also influence how much water can be released from each outlet. Under regular operations flows of 9,000 ML/day (measured at Weir 32) are not exceeded. While the release capacity of the Main Weir is much higher this structure is only used during flood operations. The Great Darling Anabranch receives unregulated flows from the lower Darling River. However, water can be released directly from the Menindee Lakes Scheme via Lake Cawndilla, which flows down Cawndilla Channel, Tandou Creek, through Packers Crossing regulator and then Redbank Creek to the Darling Anabranch. Lower River Murray system The ability to deliver large scale actions in the lower River Murray is dependent upon the management of the Commonwealth environmental water portfolio across state jurisdictions, during different river flow conditions, to meet the water requirements of environmental assets across the entire southern connected basin. Environmental water is sourced from managed releases from River Murray storages including Hume Reservoir, Menindee Lakes system, River Murray tributaries and Lake Victoria. Water 6

7 releases from Lake Victoria (an off-river storage that is oprated to provide reliable water supply for the Lower Murray below Lock 7) may be used to contribute towards achieving shortduration high flow targets at the South Australian border. Environmental water delivery to specific sites within the lower River Murray occurs in two main ways. At low river flows regulating structures or pumping can be used to manage the diversion of water into anabranches, creeks, wetlands and floodplains. At high river flows regulating structures may be overtopped and water passes overbank into floodplain and wetland sites. The ability to use environmental water to target flow rates in the lower River Murray requires the coordination of environmental releases from a number of upstream storages. Inundation of some wetlands and watercourses in the River Murray downstream of Euston (Lock 15) occurs under regulated flow rates up to 10,000 ML/day, with significant increases in the inundation of floodplains and wetlands occurring above approximately 37,900 ML/day (Green and Alexander 2006). Inflows into the Hattah Lakes occurs via the eastern arm of Chalka Creek that commences at 20,000 ML/day measured at Euston Weir (Murray-Darling Basin Authority 2012) and the area of inundation created by natural river flows significantly increases above 50,000 ML/day. The completion of water management works on the Hattah Lakes floodplain in 2013 will allow water to be pumped into the wetland system during periods of low river flows and to maintain water on the floodplain for extended periods. Downstream of Lock 7 and spanning the South Australian border is the Chowilla, Lindsay- Wallpolla Islands Icon site, which comprises a complex of anabranches, wetlands and floodplains. Channels such as Lindsay River, Mullaroo Creek and Potterwalkagee Creek are connected at normal weir pool level and regulated flows up to 10,000 ML/day. There is increasing inundation of wetlands and channels above 26,000 ML/day however significant inundation of floodplains commences at flows greater than 40,000 ML/day (Ecological Associates and SKM in prep). A range of infrastructure are under construction within the site that when operated will control flows through the anabranches, manage water to particular wetlands and enable increased area inundation of floodplains. The operation of the structures may need simultaneous manipulation of weir pool levels. During infrastructure on Mulcra Island is expected to be operational. Within South Australia many wetlands, creeks and anabranches are connected permanently to the river channel weir pools, however some sites are managed using regulating structures to reinstate more natural patterns of temporary inundation and drying sequences. River flows in the order of 40,000 60,000 ML/day begin to overtop regulating structures at floodrunners, creeks and anabranches on a localised scale producing some overbank inundation. Flows exceeding approximately 55,000 ML/day produce increased overbank inundation (Ecological Associates et al. in draft). Floodplain and wetland sites requiring high river flows for inundation include the Riverland Ramsar site (including Chowilla Floodplain), Banrock Station Ramsar site, Pike Floodplain, and Katarapko floodplain. The operation of River Murray weir infrastructure may also be used to provide water level variation. The temporary raising of weir pools increases the area of wetland inundation simulating higher peaks in river flows however requiring only low flow conditions and using much less water. The Lower Lakes receive river inflows and water levels are managed through the operation of the barrages at Lake Alexandrina. Barrage operations help to manage water and salinity levels in the lakes and also provided inflows into the Coorong. Barrage flows are managed by SA Water under the direction of the Murray-Darling Basin Authority. Strategies for managing the barrages are generally based on water level and salinity targets within Lake Alexandrina, Lake Albert and the Coorong lagoons, and maintaining hydrological connectivity between the River Murray and the Murray estuary (Australian Water Environments et al. 2011). These general strategies target a broad range of ecological outcomes. 7

8 Nature Foundation South Australia In a partnership was established between the Commonwealth Environmental Water Holder and Nature Foundation SA. Under the partnership, up to 10,000 ML of Commonwealth environmental water will be made available to Nature Foundation SA each year to undertake watering actions aimed at achieving environmental outcomes on privately managed wetlands and floodplains in the lower River Murray. Watering projects are likely to use a range of infrastructure to deliver water on site and are considered to be complementary with larger scale watering options identified in Section 6. Figure 1 belows shows a map of the Lower Murray-Darling Region. 8

9 Figure 1: Map of the Lower Murray-Darling Region (SEWPaC 2012). 9

10 2.2. Operational and management considerations for in the Lower Murray-Darling Region Throughout the year operational and management considerations will be addressed as decisions are taken to make water available for use and as these decisions are implemented. This will include refining the ecological objectives, assessing operational feasibility, potential risks and the ongoing monitoring of the seasonal outlook and river conditions. The Commonwealth Environmental Water Office, the Murray-Darling Basin Authority and state government agencies will continue to work collaboratively during to increase the effective and efficient use of environmental water through coordinated watering actions. Opportunities for coordinating watering actions will be supported by river managers implementing operating arrangements agreed by the relevant government agencies. The delivery of environmental water in the lower Murray River Region is currently constrained by the release capacities from storages and channel capacities. For , current river and floodplain work programs and potential risks to third parties will be an important consideration for the delivery of environmental water in the lower Murray-Darling Region is likely to constrain maximum flow rates at different times and locations during the year. Relevent constraints to be considered include: Maintenance works at Lock 15, which is expected to limit flows to 20,000 ML/day between July and August The construction of the Chowilla regulator, which will limit flows to 45,000 ML/day at the South Australian border during The construction of the Slaney and Pipeclay weirs (Chowilla floodplain), which is expected to limit flows to 25,000 ML/day at the South Australian border during July to September 2013, where possible. The planning and construction of various works associated with the Riverine Recovery Program South Australia (funded under the Commonwealth government s Water for the Future program) may limit flows. Further advice on the critical flow rates will be sought from project managers throughout the year. Flows greater than 60,000 ML/day at the South Australian border result in overbank inundation of floodplain throughout the Lower River Murray, including the inundation of privately owned land and public infrastructure. The risk of impacting on public and private infrastructure through the use of environmental water requires further investigation. The Commonwealth Environmental Water Office will continue to seek advice from river operators, site managers and state government agencies on feasible flow targets. Operational considerations such as delivery methods, opportunities, constraints and risks will differ depending on the inflow scenario and are summarised in Table 1. In Table 1, operational considerations are assessed against inflow scenarios that are represented by annual exceedance probability (AEP), that is, the number of years that a given inflows is equalled or exceeded, expressed as a percentage. Operational considerations and constraints documented within the Commonwealth environmental water use options: Mid-Murray Region, Murrumbidgee River Valley and Victorian Rivers provide further context for water delivery to the Lower River Murray. 10

11 Table 1: Operational considerations for the Lower Murray-Darling Region in Inflow scenario Very low (90% AEP 1 ) Low (75% AEP) Moderate (50% AEP) High (25% AEP) Very high (10% AEP) Opportunities Coordinate environmental water releases across the southern connected basin to provide systemwide, multiple site benefits. Use environmental water in conjunction with naturally occurring river flows to maximise the efficiency and effectiveness of use, for example by prolonging or managing the recession of higher flows to provide a more natural flow pattern. Pumping and water diversion via regulating structures to key sites may be considered depending on an assessment of the action and the level of river flows. River and floodplain infrastructure (weirs and regulators) may be operated in conjunction with environmental flows to maximise the area of wetland inundation. Constraints Reduced ability to provide additional environmental water within operational constraints and channel capacity due to unregulated/natural flows Reduced ability to provide additional environmental water within channel capacity due to high consumptive/irrigation demands e.g. irrigation Flow thresholds to avoid third-party impacts, such as inundation of private land or crossings, or to avoid impacts to existing river and floodplains works program may constrain the delivery of environmental water, particularly targeted peak flow rates. 1 Percentages refer to the probability of exceedance based on historical inflows for the catchment, i.e. there is a 90 per cent chance that actual flows will be greater than that amount. 11

12 Inflow scenario Very low (90% AEP 1 ) Low (75% AEP) Moderate (50% AEP) High (25% AEP) Very high (10% AEP) Release capacities and available volumes within storages may constrain the magnitude of augmentation. Risks* Availability of environmental water is insufficient to meet the desired flow regime/environmental outcome. The provision of Commonwealth environmental water may impact property and infrastructure. Not directly related to inflow scenarios Adverse environmental impacts as a result of environmental flows (e.g. blackwater, dispersal/recruitment of exotic species, mobilisation of salinity or acid sulphate soils). *See Section 6.2 for more information on risk management Valley condition Between 2000 and 2010 the Lower Murray-Darling Region received minimum inflows due to a long period of drought. When combined with the existing effects of water use and river regulation, this decade-long drought had a significant effect on the condition of the valley. The MDBA released its second Sustainable Rivers Audit report in 2012 (based on data collected from 2008 to 2010) and concluded that both the Darling and lower Murray river valleys were in poor ecosystem health. While the Darling River valley was recognised for its good riverine vegetation condition, both the Darling and lower Murray river valleys shared poor ratings for the native fish community and had ratings that ranged from very poor to moderate for the health of the macroinvertebrate community, physical form and hydrology. Drought-breaking inflows were experienced in with further high inflows experienced across the valley in , particularly during the second half of the year. These wet conditions promoted a positive ecological response across the Lower Murray-Darling Region. These ecological response included: Positive response of native vegetation (river red gum and black box) on the Great Darling Anabranch, Lindsay-Wallpolla Islands, Riverland Rasmar site and Katarapko floodplain. Not directly related to inflow scenarios Increase in fish diversity and abundance in the Lower Murray-Darling Region. Increased salt and nutrient export, with decreased salinity levels in Lake Alexandrina and the Coorong Lagoons. During the water year climate conditions were drier than average in the Lower Murray- Darling Region. Rainfall was very much below average across the entire valley while above average temperatures were experienced, particularly throughout summer. By the end of it is estimated that up to 770,000 ML of Commonwealth environmental water will be delivered through the lower reaches of the River Murray channel. Additional environmental water has also been provided through The Living Murray program. Preliminary information on the ecological response to the delivery of environmental water into the lower River Murray has indicated evidence of native fish spawning (particularly golden perch) and 12

13 increased lateral movement between the River Murray channel and fringing wetland that resulted in increased abundance and species richness of native fish within wetlands. Flows in the lower Darling River during remained in-channel. Operational releases have been delivered by the MDBA through the lower Darling River as a pulse over the spring-summer period and as high baseflows during autumn to meet environmental orders in the lower River Murray. Low level baseflows have persisted in the Great Darling Anabranch due to some of the floodplain lakes still draining from flooding in Conditions within the Lower Lakes and Coorong have benefited from increased inflows and barrage outflows throughout the last water year. Water levels and salinity concentrations within the Coorong South Lagoon and Lake Alexandrina have been maintained within the target range, with salinity levels in Lake Alexandrina considered to be representative of pre-drought levels (DEWNR 2013). The current average salinity levels within Lake Albert has improved from however this has remained higher than the target value. The result of barrage flows and lake levels has maintained hydrological connectivity between the lakes and fringing wetlands. South Lagoon Coorong water levels during summer, compared to , indicate that the early use of environmental water has contributed to maintaining higher water levels for a longer period of time, improving aquatic habitat conditions (DEWNR 2013). Resulting from the improved habitat conditions, aquatic flora and fauna at the Lower Lakes and Coorong are begining to show signs of recovery. Fish species diversity in the North and South Lagoon of the Coorong have increased, diadromous fish (including congolli, common galaxias and lampreys) have been recorded in much higher numbers with evidence of spawning during , and black bream are being observed (DEWNR in prep.; DEWNR 2013). Bird populations are slowly recovering with higher diversities and abundances for many species being recorded, supported by improved food resources. Fairy terns were recently recorded having successfully bred for the first time since pre-drought but are still in low abundances (DEWNR in prep.). Ruppia tuberosa in the Coorong South Lagoon was observed flowering in which is an improvement from (DEWNR 2013). Despite the drier catchment conditions experienced during (and near record levels of water usage across the River Murray valley), end of year storages in the southern connected basin remain relatively high due to periodic rainfall events with the upper catchments of the Darling and Murray rivers. 13

14 3. Water availability 3.1. Commonwealth environmental water holdings in the Lower Murray- Darling Region for Commonwealth environmental water holdings available for use in in the Lower Murray-Darling Region are shown in Table 2 below. Table 2: Commonwealth environmental water holdings in the Lower Murray-Darling Region as at 30 April Entitlement type Lower Darling (General Security) South Australia (High Security) Total Lower Murray River Valley 1 Total Southern Connected Basin 2 Entitlement held (GL) Long-term average annual yield (GL) Estimated carryover from (GL) Forecast water availability for (GL )4 1, ,147-1,527 5 Notes: 1. The boundary between the Mid-Murray and Lower Murray-Darling regions used by the Commonwealth Environmental Water Office for planning do not precisely align with entitlement types. 2. The southern connected basin includes the Murrumbidgee, Murray, Lower Darling, Goulburn, Campaspe (excluding Coliban) and Loddon entitlements. 3. Future decisions about use, transfers and the ability to deliver already approved actions will affect carryover from Forecasts are based on the best available information including State forecasts and historical inflow scenarios. Forecasts include carryover from Forecasts for regulated catchments are given to the nearest whole gigalitre except where the entitlement held by the Commonwealth is below 1 GL. 5. Total forecast water available in the the southern connected basin does not include allocation in spillable water accounts in Victoria. These figures do not include supplementary, unregulated or ground water accurals in the southern connected basin. The full list of Commonwealth environmental water holdings can be found at and is updated monthly. A portfolio management statement for the Lower Murray is currently in development and will be made available at Other sources of environmental water allocations Other sources of environmental water that may complement Commonwealth environmental water delivery in the Lower Murray-Darling Region include water held by The Living Murray program, Victorian Environmental Water Holder, NSW Office of Environment and Heritage and the South Australian Department of Environment, Water and Natural Resources. Table 3 below outlines the different environmental water entitlements held by other water holders. 14

15 Table 3: Other potential sources of environmental water in the Lower Murray-Darling Region for Source Management Authority Entitlement Environment Entitlement - The Living Murray Program South Australian Class 9 Wetlands South Australian environmental water reserve South Australian water environment The Living Murray Bulk Entitlement (River Murray Flora and Fauna) Conversion Order 1999 Bulk Entitlement (River Murray Flora and Fauna) Conversion order 1999 The Living Murray Murray-Darling Basin Authority South Australian Department of Environment, Water and Natural Resources Victorian Environmental Water Holder GL of multi-state entitlements for use at six icon sites 200 GL for managed pool level wetlands 6-18 GL 45.0 GL 27.6 GL high reliability 40 GL unregulated 18.3 GL high reliability, GL low reliability 34.3 GL unregulated Bulk Environment (River Murray Snowy Environmental Reserve) Conversion Order 2004 Water Shares - Snowy River Environmental Reserve 29.8 GL high reliability- River Murray 10.5 GL high reliability and 6.4 GL low reliability Murray River Environmental Entitlement (Goulburn system The Living Murray) 2007 Environmental Entitlement (Campaspe River The Living Murray) 2007 NSW Adaptive environmental water entitlement NSW Office of Environment and Heritage 6.1 GL high reliability and 17.8 GL low reliability Goulburn River 45.2 GL high reliability 157 GL low reliability 0.1 GL high reliability 5 GL low reliability 30 GL of River Conveyance entitlements 2 GL of High Security entitlements NSW Murray Water access entitlement The Living Murray 5.1 GL high security 83.0 GL general security GL supplementary 12.9 GL unregulated 15

16 NSW Darling Water access entitlement The Living Murray Barmah-Millewa Environmental Water Allowance NSW Office of Environment and Heritage, Victorian Environmental Water Holder 0.5 GL high security 47.8 GL general security GL supplementary Up to 150 GL annual allocation (100 GL high security and 50 GL low security) of Barmah- Millewa Environmental Water Allowance 1 The GL Living Murray entitlement includes Victorian, New South Wales and South Australian entitlements Natural or unregulated flows and planned environmental water In addition to water entitlements held by environmental water holders, environmental demands may also be met via natural or unregulated flows and water provided for the environment under rules in the Murray-Darling Basin Agreement, Water Sharing Plan for the New South Wales Murray and Lower Darling Regulated Rivers Water Sources (2003) and the Water Allocation Plan for the River Murray Prescribed Water Course South Australia (these contributions of environmental water are hereafter referred in this document as planned environmental water ). Planned environmental water relevant to the Lower Murray-Darling Region includes: Additional Dilution Flow (ADF) NSW Lower Darling Environmental Contingency Allowance NSW Murray Regulated River Water Source Additional Environmental Allowance South Australian River Murray Class 9 water access entitlement (pool level managed wetlands) The Bureau of Meteorology provides a seasonal streamflow forecasting service, which estimates the potential for low, median or high flows for the coming three months ahead. 16

17 4. Planning for water use in the Lower Murray- Darling Region in Planning for a range of inflows in In addition to influencing opportunities, constraints and risks in relation to environmental watering (see Table 1), inflows are a a primary driver of resource availability. Resource availability also reflects a combination of allocations available to the Commonwealth Environmental Water Holder (Section 3.1 above) and other environmental water holders (Section 3.2) as well as natural or unregulated flows and planned environmental water (Section 3.3). Given the variable rainfall experienced across the Basin, inflows are difficult to accurately forecast. As shown in Table 2, carryover from for the southern connected basin is likely to be in the range of approximately GL, with forecast early season (up to 31 July 2014) likely to be in the order of GL, giving a total allocation range of approximately GL available for use in early Consideration of this allocation range relative to the total entitlement volume (Table 2) and the full range of inflows that may be possible suggests that resource availability early in may be moderate to high. From this starting point, the full range of possible inflows suggest that resource availability over the course of the year could be between low and very high, and unlikely to become very low (Figure 2). As such, the water use options described in Section 6 have been developed for a range of resource availability between low and very high. Figure 2: How inflows may vary and impact on water resource availability over the course of in the Lower Murray-Darling Region, from a starting point of Moderate to High resource availability. 17

18 4.2. Implementing watering actions throughout the year Resource availability will change over the course of as new allocation announcements are made, water is used or traded. Climatic conditions will also affect the potential for inflows. The Office will regularly review allocations against environmental entitlements and seasonal streamflow forecasts over the course of the year to assess resource availability. This assessment, along with up-to-date information on environmental needs and the operational and management conditions (Section 2) will allow the watering options in Section 6 to be refined for implementation as required. 18

19 5. Water use options and the Basin Plan s environmental watering plan objectives 5.1. Demonstrating how Commonwealth environmental water in will contribute to the Basin Plan s environmental watering plan objectives Lower Murray-Darling Region Commonwealth environmental water use options for the Lower Murray-Darling Region in include the following four flow types: base flows freshes bankfull overbank These flow types are illustrated in Figure 3 of the document Commonwealth environmental water use options : Planning approach. Wetlands and floodplains are also expected to be inundated. The ecological response from delivering Commonwealth environmental water is reflected in the expected outcomes. The Commonwealth Environmental Water Office (the Office) has used the best available science to determine how the expected outcomes of Commonwealth environmental water contribute towards the objectives of the Basin Plan s environmental watering plan. Table 4 shows the expected outcomes that may be derived from Commonwealth environmental watering using different flow types in the Lower Murray-Darling Region and the relevant Basin Plan objectives. 19

20 Table 4: Expected outcomes from the use of Commonwealth environmental water in the Lower Murray-Darling Region. Flow Type Expected outcomes for Contributions to longer term outcomes Contribution to the following Basin Plan objective Base flows and freshes Sediment transport Connectivity Ecosystem function Resistance Population resilience Resilience Base flows, freshes and bank-full Refuge Landscape refuge Resilience Salinity Chemical Water quality All flow types Within ecosystem diversity Landscape ecosystem diversity Biodiversity Vegetation condition and reproduction Landscape vegetation diversity Vegetation recruitment and extent Fish reproduction Landscape fish diversity Fish larval growth and survival Waterbird survival and condition Landscape bird diversity Waterbird reproduction Other vertebrate condition Other vertebrates Other vertebrate reproduction Hydrological connectivity Connectivity Ecosystem function Biotic dispersal End of system flows 20

21 6. Water use options for Watering options Potential watering options for have been developed for the Lower Murray-Darling Region. These reflect the approach to supply Commonwealth environmental water to contribute to the overall environmental objectives under the Basin Plan s environmental watering plan. These watering options have been designed to specifically enable the scaling of actions across several potential inflows scenarios. This provides flexibility for water use to best complement natural inflows. Options have been developed based on the hydrological characteristics of Low to High inflow scenarios, in consideration of the constraints and risks highlighted in Section 2.2. These options are also applicable during periods of extreme dry and very high inflows conditions should these conditions prevail. Broadly, the aim of Commonwealth environmental watering in the Lower Murray-Darling Region during will be to support the on-going environmental recovery that commenced following the breaking of the drought (see Section 2.3). For some parts of the system this will mean providing river flows to support fish reproduction, provide suitable habitat for water birds and other native vertebrate fauna, and contribute towards the maintenance and recruitment of water dependent vegetation in wetlands, the riparian zone and on floodplains. Any volumes described in the options tables below are approximations only. The final volume of Commonwealth environmental water made available will depend on river conditions at the time of use, other environmental water contributions and in consideration of Basin-wide needs. The water use options identified do not represent a commitment for use, nor do they reflect all the possible water use options available. Additional water use options may be identified throughout the water year. The Office welcomes information from the community on how environmental water can best be used and managed. If you have any comments or suggestions, please call or send an to: ewater@environment.gov.au 21

22 Table 5: Summary of water use options for the Lower Marray-Darling Region in Applicable level(s) of resource availability (see Section 4) Options 1 (low), 2 (mod) and 3 (high) River Murray from Euston to Lower Lakes and Coorong Option 4 Lower Darling River Low Moderate High Very High Support increased variability in-channel river flow by contributing towards increased baseflows and augmenting natural flow events to protect and maintain the diversity and condition of native species and communities. Support increased variability of river flows by contributing towards increased baseflows, and augmenting natural flow events for in-channel freshes and bankfull flows to maintain landscape diversity and improve condition of native species. Support increased variability of river flows by contributing towards increased baseflows, and augmenting natural flow events for in-channel freshes, bankfull and overbank flows to maintain and improve the diversity and condition of native species and support the recovery of floodplain ecosystems. Options unlikely to be pursued under this resource availability. Support increased variability of river flows by contributing towards baseflows and freshes to maintain and improve ecosystem diversity and native fish populations. Option 5 Great Darling Anabranch Options unlikely to be pursued under this resource availability. Support in-channel flows by contributing towards baseflows and freshes to maintain and improve ecosystem diversity and native fish populations. Note: Under certain resource availabilities, options may not be pursued for a variety of reasons including that environmental demand may be met by unregulated flows and that constraints and/or risks may limit the ability to deliver environmental water. 22

23 Option 1 River Murray from Euston to the Lower Lakes and Coorong Catchment: Lower Murray Complex: River Murray Site: River Murray from Euston to Lower Lakes and Coorong Applicable level(s) of resource availability: Low Relevant flow component: Base flows Fresh Bank-full flows Over-bank flows Expected inundation extent: Floodplain inundation Wetland inundation Summary of watering option: Watering options under low resource availability will aim to protect and maintain the diversity and condition of native species and communities within the river channel and in the Coorong and Lower Lakes. Expected outcomes from such watering actions would include reduced salinity, increased sediment transport, contribute to nutrient and carbon cycling, maintenance of wetland refuges and maintainence of hydrological connectivity between the River Murray channel, Lower Lakes and Coorong. This in turn will support the maintainence aquatic vegetation condition (such as Ruppia) in the Coorong, and the dispersal and condition of native fish. Environmental water use options within the lower River Murray channel may involve: a) supplementing base flow up to 6,000 10,000 ML/day, and b) augmenting natural flow events between October and January to extend natural flow events targeting up to 26,000 ML/day for minimum peak flow duration of days. Watering options will aim to contribute towards barrage operations at the Lower Lakes and Coorong, with highest barrage outflows between October and February, and subject to water availability, supplementing additional outflows at other times during the year. Targeted water delivery to high priority individual wetland sites may be considered as part of this option; these may include (but are not limited to) sites associated with: the Riverland Ramsar site, the Chowilla-Lindsay-Wallpolla Islands Icon site, Hattah Lakes, Mallee wetlands, Fletchers Creek, Bottle Bend Lagoon, Carrs, Capitts and Bunberoo creeks, Berri Saline Water Disposal Basin and Disher Creek Saline Water Disposal Basin. Timing September 2013 to April 2014 Volume of Commonwealth environmental water To supplement river flows to achieve a minimum total annual flow at the barrages of 650 GL/year. Operational considerations and feasibility: This watering option is based on dry inflow conditions in the River Murray. For the purpose of identifying watering options relevant to this scenario, dry inflow conditions have been generally characterised by flow rates at Euston of around 6,000-10,000 ML/day with some flow variability. Flows to the South Australian border are likely to be close to the monthly entitlement (between 3,000 to 7,000 ML/day), with the potential for natural flows of short 23

24 duration in the order of up to 10,000 15,000 ML/day between July and November. Commonwealth environmental water will be delivered via river flows and is expected to be sourced from a combination of managed releases from River Murray storages including Hume Reservoir and Menindee Lakes system, natural River Murray inflows and return flows from upstream tributaries. Under some circumstances pumping to discrete wetland sites may be considered. When using a combination of upstream water storage releases, tributary inflows and the operation of Lake Victoria to augment flows, channel capacities and river operations may limit opportunities to augment flows during dry inflow conditions. The ability to deliver additional water from the Goulburn River, timed with River Murray flows will be important in augmenting natural flows. Opportunities to maximise the benefit of low river flows for riparian vegetation and wetland connectivity may be limited however may occur through the management of River Murray weir infrastructure or through the assistance of infrastructure such as pump, constructed channels and wetland regulators. Delivery of environmental water during summer is likely to be constrained due to limitations on channel capacity supplying other water users and to avoid unintentional inundation of floodplain in the Mid-Murray Region. Barrage operations at the Lower Lakes are actively managed throughout the year. Under dry conditions operations may aim to maintain water levels at Lakes Alexandrina and Albert between m AHD and maintain flows through barrage fishways for a minimum of 3 to 6 months during spring. Current works and measures programs (including The Living Murray and Water for the Future programs) are likely to be in place and may constrain supplementation of flows using environmental water. Higher flow targets will only be pursued after natural flows exceed the inundation thresholds for work projects, with advice of river operators, site managers and state government authorities. Determining appropriate rates of rise and fall for the purpose of managing the recession of natural high flow events will be developed based on expert advice however may be constrained by release limits at the major storages and river channel capacities. 24

25 Option 2 River Murray from Euston to the Lower Lakes and Coorong Catchment: Lower Murray Complex: River Murray Site: River Murray from Euston to Lower Lakes and Coorong Applicable level(s) of resource availability: Moderate Relevant flow component: Base flows Fresh Bank-full flows Over-bank flows Expected inundation extent: Floodplain inundation Wetland inundation Summary of watering option: Watering options under moderate resource availability will aim to maintain landscape diversity and improve the condition of native species within channel, along the riverbank and in fringing wetlands. This will include continuing the recovery of species and communities in the Lower Lakes and Coorong. Expected outcomes are anticipated to build on those in Option 1, including supporting fish and waterbird reproduction, contribute to recruitment and improving condition of riverine and aquatic vegetation, supporting hydrological connectivity between the River Murray channel and fringing wetlands, and the Lower Lakes and Coorong. Environmental water use options within the lower River Murray channel may involve: a) supplementing base flow up to 6,000 10,000 ML/day, b) low-level freshes targeting a minimum 26,000 ML/day peak flow for a minimum period of 21 days during September to January, c) augmenting natural high flow events between September and January to extend high flow events targeting a peak flow of around 30,000 40,000 ML/day for a minimum of 14 days, and d) managing natural high flow recession. Watering options will aim to contribute towards barrage operations at the Lower Lakes and Coorong, with highest lake inflows during October to January, and supporting barrage outflows into the Coorong throughout the year. Targeted water delivery to high priority individual wetland sites may be considered as part of this option; these may include (but are not limited to): sites associated with the Riverland Ramsar site, Chowilla Floodplain and Lindsay-Wallpolla Islands Icon site, Mallee wetlands, Hattah Lakes, Fletchers Creek, Bottle Bend Lagoon, Carrs, Capitts and Bunberoo creeks, Berri Saline Water Disposal Basin and Disher Creek Saline Water Disposal Basin. Timing September 2013 to June 2014 Volume of Commonwealth environmental water To supplement river flows to achieve a minimum total annual flow at the barrages of >1,000 GL/year. Operational considerations and feasibility: This watering option is based on median inflow conditions in the River Murray. For the purpose of identifying watering options relevant to this scenario, median inflow conditions has been generally characterised by variable base flow rate at Euston between 3,000 25

26 12,000 ML/day, and baseflows at the South Australian border that are at or above the South Australian monthly entitlement however less than 10,000 ML/day. Natural freshes may occur throughout the lower River Murray during Spring and Summer with variable flow rates of 15,000 35,000 ML/day. Commonwealth environmental water will be delivered via river flows and is expected to be sourced from a combination of managed releases from River Murray storages including Hume Reservoir and Menindee Lakes system, natural River Murray inflows and return flows from upstream tributaries. Under some circumstances pumping to discrete wetland sites may be considered. When using a combination of upstream water storage releases, tributary inflows and the operation of Lake Victoria to augment flows, operations may be limited to augmenting flows up to 10,000 15,000 ML/d. The ability to deliver additional water from the Goulburn River and lower Darling River, timed with River Murray flows will be important in augmenting natural flows. Opportunities to maximise the benefit of low river flows for riparian vegetation and wetland connectivity may occur through the management of River Murray weir infrastructure. Delivery of environmental water during summer may be constrained due to limitations on channel capacity supplying other water users and to minimise third party impacts. Barrage operations at the Lower Lakes are actively managed throughout the year. Under median conditions operations may aim to maintain water levels at Lakes Alexandrina and Albert between m AHD and maintain flows through barrages and fishways throughout the year. The cycling of lake levels (raising and lowering) may be undertaken to increase the export of salt from Lake Albert, subject to water availability. Differential releases from the barrages will be managed to target specific outcomes throughout the year. Increased barrage flows during late Summer-early Autumn is expected to support improved conditions in the Coorong. Current works and measures programs (including The Living Murray and Water for the Future programs) are likely to be in place and may constrain supplementation of flows using environmental water. Higher flow targets will only be pursued after natural flows exceed the inundation thresholds for work projects and with the advice of river operators, site managers and state government authorities. Determining appropriate rates of rise and fall for the purpose of managing the recession of natural high flow events will be developed based on expert advice however may be constrained by release limits at the major storages and river channel capacities. 26

27 Option 3 River Murray from Euston to the Lower Lakes and Coorong Catchment: Lower Murray Complex: River Murray Site: River Murray from Euston to Lower Lakes and Coorong Applicable level(s) of resource availability: Moderate to High Relevant flow component: Base flows Fresh Bank-full flows Over-bank flows Expected inundation extent: Floodplain inundation Wetland inundation Summary of watering option: Watering options under high resource availability will aim to maintain landscape vegetation and wetland diversity, improve the condition of water dependent native species and support the recovery of floodplain ecosystems. Expected outcomes will build on those of Option 2 and include supporting fish and waterbird breeding, contribute to fish and waterbird recruitment, improving the condition and supporting recruitment of floodplain vegetation, supporting lateral and longitudinal hydrological connectivity between the River Murray Channel, floodplain and wetlands. Environmental water use options within the lower River Murray channel may involve: a) supplementing base flow up to 10,000 ML/day during February to May, b) in-channel freshes targeting a minimum 26,000 ML/day peak flow for a minimum period of 30 days during September to February, c) augmenting natural high flow events between August January to extend high flow events targeting 40,000 ML/day for a minimum of 60 days, up to a maximum peak flow of 60,000 ML/day, and d) to manage natural high flow recession. Watering options will aim to contribute towards barrage operations at the Lower Lakes and Coorong, supplementing lake inflows during October to January, and supporting continuous barrage outflows into the Coorong throughout the year. Targeted water delivery to high priority individual wetland sites may be considered as part of this option; these may include (but are not limited to): sites associated with the Riverland Ramsar site, Chowilla Floodplain and Lindsay-Wallpolla Islands Icon site, Mallee wetlands, Hattah Lakes, Fletchers Creek, Bottle Bend Lagoon, Carrs, Capitts and Bunberoo creeks, Berri Saline Water Disposal Basin and Disher Creek Saline Water Disposal Basin. Timing August 2013 to June 2014 Volume of Commonwealth environmental water To supplement river flows to achieve annual flow at the barrages of >6,000 GL/year, or depending on natural river flows achieve a minimum three year rolling average of 2,000 GL/year. Operational considerations and feasibility: This watering option is based on wet inflow conditions in the River Murray. For the purpose of identifying watering options relevant to this scenario, wet inflow conditions have been generally characterised by variable base flow rate at the South Australian border that are above the South Australian monthly entitlement. Flows into South Australia may at times 27