Trentham System. Water Supply Demand Strategy. Final Report March to 2060

Transcription

1 Trentham System Water Supply Demand Strategy 2011 to 2060 Final Report March 2012

2 TABLE OF CONTENTS Executive Summary 4 1. Introduction 7 2. Overview Key Features How Water is Delivered to Trentham Customer Profile 9 3. Recent Experience Water Supply Water Demand Water Quality Waterplan 2055 Review Levels of Service Climate Change / Variability Scenarios Demand Forecast Current System Demand - Baseline Demand Future System Demand Population and Demand Growth Residential Population Growth Non- Residential Demand Growth Total Growth in Residential and Non-residential Demand Environmental Demand Climate Change Impact on Demand Behaviour Change and Bounce-back Improved Water Quality Summary of System Demand Impacts Supply Forecast General Catchment Management System Performance Evaluation Demand Reduction Measures Permanent Water Saving Rules (PWSR) Reduction of Operational Water Water Saving Incentives and Community Education 22 Page 2

3 9.4. Pricing Incentives Summary of Demand Reduction Measures Additional Supply Measures Permanent Water Market (where available) Temporary Water Market (where available) Groundwater Connect to Fern Hill Storages Connect to Tylden Additional Water Private Rain Water tanks Alternative Water Sources Water Quality Measures Options Analysis Demand Reduction Additional Water Options Summary Management of Risk and Uncertainty General Murray Darling Basin Plan Proposed Actions Trentham System Short-term Actions Long-term Actions Community & Stakeholder Engagement 30 APPENDICES Appendix 1: Appendix 2: Alternative Water Atlas Long List of Supply Options Page 3

4 Executive Summary Introduction Coliban Region Water Corporation is a state owned water authority that provides water and wastewater services to a region with a population of 140,000 people, across 16,550 square kilometres of Central and Northern Victoria. The service area covers 49 towns in nine separate supply systems of which Trentham Groundwater system is one. The Water Supply Demand Strategy (WSDS) identifies the best mix of measures to maintain a balance between the demand for water and the available supply in urban supply systems, now and 50 years into the future. Coliban Water is required to consider the social, environmental and economic costs and benefits and the actions needed to address population growth, nonresidential demand for water and potential climate variability. The Trentham Groundwater System The Trentham Groundwater system supplies an estimated residential population of 816 with 513 customer connections; 87% are residential and 13% are non-residential. The Trentham water supply system is located in the upper (unregulated) reaches of the Coliban River system in the Campaspe Basin. Natural surface spring water has historically provided the majority of water supply for Trentham with spring water flowing into the Trentham Reservoirs (combined capacity of 90 ML). Supply is supplemented with groundwater bore supply in the summer months or during drought under a 48 ML groundwater extraction licence. There is currently no bulk entitlement to the spring surface water. However, a process is underway to convert Coliban Water s pre-existing historic right to spring water into a bulk entitlement that is tentatively assessed at 120 ML per year averaged over a rolling three year period. The spring and bore groundwater is treated at the Trentham Treatment Plant and the treated water complies with the water quality standards specified in the Safe Drinking Water Act Recent Experience The Trentham supply system is considered Coliban Water s most reliable system with the two Trentham storages typically remaining fairly full or close to full throughout the year. The supplementary groundwater bores have been able to provide an effective back-up supply. Through the prolonged drought of 2002 to 2010, Trentham experienced the most moderate level of water restrictions of any of Coliban Water's water supply systems with Stage 1 and Stage 2 water restrictions in force for most of the period between November 2002 and October Permanent Water Saving Rules (PWSR) have been in place since October Annual water demand ranged from a maximum of 143 ML in 2001/02 (unrestricted year) to a minimum of 84 ML in 2010/11 when extremely high rainfall was received. The mild water restrictions had no obvious impact on Trentham s water demand. The current estimated PWSR annual raw water demand is 105 ML. The average annual residential consumption for the four years from 2007 to 2011 was 121 kl per property or 20% less than the regional average of 153 kl per property. The average annual nonresidential consumption for the last four years was 256 kl per property or 70% less than the regional average of 855 kl per non-residential property. A review five years on if Coliban Water s last Water Supply Demand Strategy, Waterplan 2055, is available from Coliban Water s website. Page 4

5 Level of Service The Water Supply-Demand Strategy is developed to achieve both: A PWSR supply reliability of 95% (where PWSR demand would be supplied in 95 out of 100 years and water restrictions would not be expected in more than 5 years in 100; and A desired restriction level of no worse than Stage 1. More severe restrictions, such as Stage 3, would only be expected if severe or unexpected water shortages occur. Supply and Demand Balance The available supply to the Trentham Groundwater system is currently estimated at 143 ML per year and is sufficient to meet the current PWSR raw water demand of 105 ML. However, the PWSR annual demand for water is estimated to double in the next 50 years and increase to 209 ML by year The increasing demand is primarily due to the growth in population, forecast at 1.5% per annum. The potentially hotter and drier climate is also forecast to add to demand by as estimated 9%. However, offsetting these two factors is the continuation of changes in customer consumption behaviour supported by community education and technology improvements. Customers have made a remarkable contribution to reducing water consumption across our region and trends indicate that customers continue to be very aware of their water consumption with an estimated reduction in household consumption of 10% over the next 50 years. The current available supply of 143 ML per year is estimated to decline slightly to 135 ML by year 2060 due to the potential hotter and drier climate. The increasing demand and the declining supply will lead to a potential shortfall in supply from about the year 2030 with an estimated maximum shortfall of 75 ML in year Supply ML per year Trentham System Forecast Supply and Demand FORECAST DEMAND FORECAST AVAILABLE SUPPLY Meeting Supply-Demand Shortfall Supply reliability of the Trentham system is estimated to greater than 95% over the next 10 to 15 years which will mean there is an estimated 5% probability of water restrictions in any year. Water restrictions, if required, are likely to be Stage 1 or Stage 2. Supply reliability is estimated to decline after year to a point where water restrictions would be necessary every year by year Additional permanent water is necessary. The maximum shortfall in the Trentham system is estimated to be 75 ML by year The supply available from the Trentham surface spring water is currently estimated to be 120 ML per year; however, further investigation is needed to more accurately establish the future supply volumes and reliability. Page 5

6 Only one of the two existing groundwater bores is operational which limits groundwater extraction to 32 ML per year. It is proposed to bring the second bore into operation to access the full entitlement of 48 ML per year and to provide operational redundancy. Investigation is required into the option to establish additional groundwater bores to meet part or the entire supply shortfall. Other options to source additional water are the connection of Trentham to the presently decommissioned Fern Hill storages (118 ML capacity) by a 12 kilometre raw water pipeline or the connection to Tylden by a 16 treated water kilometre pipeline. The potential impacts of the Murray Darling Basin Plan will become clearer over the next two to five years. The Plan will guide the management of water resources and aims to balance the water needs of the environment and other uses across the Basin s four states and one territory. The draft Plan identifies 12 GL to be recovered for the Campaspe River system and possibly more to contribute to the needs of the River Murray. Most aspects of the Plan will take effect in Victoria in Coliban Water s Trentham supply is likely to continue with little or no effect. Water Supply Demand Strategies are next due for renewal in 2017 which will be the appropriate time to incorporate any required changes. Further information regarding other possible alternative water supply considerations is available on Coliban Water s website. Extracts from the Alternative Water Atlas relating to the Trentham system are contained as Appendix. Proposed Actions Trentham System The proposed strategy to address the shortfall in supply over the next 50 years: Coliban Water should continue to manage and support, within the means that it has to do so through the planning process, only proper and orderly development within the catchment to protect raw water supply. Continue with the main replacement and leakage detection programs to minimise nonrevenue water; Investigate and accurately determine the supply available from the Trentham spring surface water supply; Reinstate the second groundwater bore; and Investigate and connect Trentham to an additional long-term supply to such as: o o o Additional groundwater bores Connection to the Fern Hill storages Connection to Tylden (Kyneton) system. Page 6

7 1. Introduction Coliban Region Water Corporation is a state owned water authority that provides water and wastewater services to a region with a population of 140,000 people, across 16,550 square kilometres of Central and Northern Victoria. The service area covers 49 towns in nine separate supply systems of which the Trentham Groundwater system is one. The Water Supply Demand Strategy (WSDS) identifies the best mix of measures to maintain a balance between the demand for water and the available supply in urban supply systems, now and 50 years into the future. Coliban Water is required to consider the social, environmental and economic costs and benefits and the actions needed to address population growth, nonresidential demand for water and potential climate variability. The development of Water Supply Demand Strategies is a requirement of water corporation s Statement of Obligations and are developed with close reference to the 2011 Guidelines for the Development of a Water Supply Demand Strategy (Version 2) issued by the Department of Sustainability and Environment. The supply-demand balance is tracked and reported on annually against the WSDSs and the WSDSs are thoroughly reviewed every five years. The development of WSDSs relies on many assumptions and estimates (including water availability, climate change, customer demands and growth) and the resultant recommendations are thus a guide to probable future needs, projects, capital investment and timing. It is therefore important to continually track and review performance on a regular basis and to also implement more serious drought response measures if and when required. Page 7

8 2. Overview 2.1. Key Features Town Supplied Trentham. Customers 513 customer connections and an estimated residential population of 816, which is 0.7% of our region connections and 0.6% of the total estimated residential population. Source of Water Natural spring water with an estimated average annual yield of 120 ML and a ground water licence of 48 ML. Coliban Water has a role to play as a referral authority in the proper and orderly implementation of Victoria Planning Provisions through Municipal Planning Schemes. Water Treatment Plant The town receives treated water from the Trentham Water Treatment Plant. Water Storages Trentham Reservoir No.1 and Reservoir No.2 with combined capacity of 90 ML constructed in 1911 and 1939 respectively How Water is Delivered to Trentham The Trentham water supply system, as shown in Figure 1, is located in the upper (unregulated) reaches of the Coliban River system in the Campaspe Basin. Natural spring water flows into Reservoir No. 1 and from there into Reservoir No. 2. Historically, the spring has provided the majority of water supply for Trentham and has been supplemented with bore supply in the summer months or during drought. Bore water is pumped into Reservoir No. 1. Coliban Water has two bores however only one is presently operable which does not enable the full ground water licence volume to be extracted. The water is treated at the Trentham Water Treatment Plant (capacity 0.7 ML per day) and supplied to the town. The treatment consists of microfiltration, ozone and disinfection. Page 8

9 Figure 1 Trentham Water Supply System 2.3. Customer Profile Of the 513 customer connections 87% are residential and 13% are non-residential. The average annual residential consumption for the four years of was 121 kl per property or 80% of the regional average of 153 kl per property.. The average annual non-residential consumption for the four years of was 256 kl per property or 30% of the regional average of 856 kl per property. The three largest users are the Trentham Hospital with annual consumption of 3 to 4 ML, the Trentham Swimming Pool with 1 to 3 ML and a plant nursery with 1 to 2 ML. Table 1 shows the Trentham residential population and number of water connections. Table 1: Trentham system Population and Service Connections Service Connections 2011 Residential Population 2011 Trentham Water Supply System Total Connections Residential Connections Non residential Connections Page 9

10 3. Recent Experience 3.1. Water Supply The water supply is natural surface spring water and a groundwater licence. There is currently no bulk entitlement to the spring surface waters that flow into the Trentham storages. However, a process is underway with the Minister for Water to convert Coliban Water s pre-existing right to spring surface water into a bulk entitlement. Preliminary investigations estimated the spring s annual yield to be 84 ML in drought conditions, 121 ML in normal conditions, and up to 145 ML in wet years. A detailed study is necessary to establish accurate yield figures of the surface spring. The proposed bulk entitlement would convert the historic right to water for Trentham to an average of 120 ML per year over a rolling three year period. The groundwater system supplying the spring source is a fractured rock aquifer with a catchment area of approximately 80 hectares that is not located in a Water Supply Protection Area or Groundwater Management Area. The main recharge area near the Trentham Reservoirs is a collapsed volcano structure. There is a groundwater licence of 48 ML which enables water to be extracted from two bores only one is presently operational (Bore No. 1). The maximum water that has been extracted from Bore No. 1 is approximately 32 ML in any year. The Trentham supply system is considered Coliban Water s most reliable system with the two storages typically remaining fairly full or close to full throughout the year. The supplementary groundwater bores have been able to provide an effective back-up supply Water Demand Trentham system demand is the total amount of water extracted from the surface spring water and the Trentham groundwater bores to meet customer consumption and operational water needs. The total system demand and water restriction levels over the last 10 years are shown in Figure 2. Annual Raw Water Demand megaliters Trentham System Annual System Demand Restriction Level Raw Water Demand Restriction Level Figure 2: Trentham Annual Demand and Water Restriction Levels Through the prolonged drought, Trentham experienced the most moderate level of water restrictions of any of Coliban Water's water supply systems. Stage 1 water restrictions were introduced in November 2002 and were generally in force for the next four years to July In that period, Stage 2 water restrictions were in force for 7 months in Stage 1 water restrictions were again in force for 9 months from January to October Permanent Water Saving Rules were in force for 7 months from July 2006 and now have been in place since October Page 10

11 Annual water demands have ranged from 143 ML in 2001/02 (unrestricted year) to a minimum of 84 ML in 2010/11 (PWSR). The low demand of 2010/11 was due to extremely high rainfall. Table 2 shows the components of system demand over the last 10 years Table 2: Components of Trentham Demand Component Percentage (%) Residential consumption 53% Non-residential consumption 19% Operational water 28% TOTAL 100% Stage 1 water restrictions and changes in customer consumption behaviour resulted in reductions in residential demand of 15 to 20% from the unrestricted demands of years 2000/01 and 2001/02. There was no obvious difference between the impact of Stage 1 and PWSR. The water required for operational needs and water lost is known as operational water. Operational water includes the water required to backwash and clean the treatment plant filters, water losses can be incurred through leakage, evaporation in service basins and pipeline bursts or from the use of fire hydrants and the flushing of mains to maintain general pipeline health. The amount of operational water comprised 39% of the annual system demand in 2007/08 while in the two years of 2003/04 and 2004/05 it comprised 16% of the total system demand Water Quality Treated water complies with the water quality standards specified in the Safe Drinking Water Act Waterplan 2055 Review A review five years on of Coliban Water s last Water Supply Demand Strategy, Waterplan 2055, is available from Coliban Water s website. It outlines our progress against the measures which were detailed in the Waterplan 2055 to ensure long-term water security for our region. In the context of the long-term climate variability challenge, the review summaries our progress with each of the Waterplan 2055 initiatives under the following categories: Urban Savings Rural Savings Recycled Water use Sourcing Additional supply Other Projects Page 11

12 4. Levels of Service Coliban Water is committed to providing the systems and infrastructure to support residential, business and industry needs throughout our region. With the major investments made in supply infrastructure in central Victoria through the recent Millennium Drought of 2002 to 2010, significant additional works are not anticipated to be required in the Coliban Water region over the next 5-10 years to maintain the objective for water security levels of service. However growth combined with weather variability and the potential for changes to our future climate may result in water shortages or drought and therefore the need for water restrictions. The Level of Service we aim to provide to customers has two components: 1. Reliability of Supply Coliban Water s objective is to provide sufficient water to meet customer demands of Permanent Water Saving Rules (PWSR) at 95% supply reliability. This means that PWSR would be in place 95 years out of every 100 years and water restrictions should not occur more often than the remaining 5 years out of every 100 years. 2. Maximum Restriction level (minimum water provision) Coliban Water s objective is that in those years where restrictions are necessary, we would try to keep restrictions to no worse than Stage 1. However in the event of severe or unexpected water shortages, restrictions may need to be more severe, such as Stage 3. Under the Victorian Government s 2011 Model Water Restriction Review, Stage 1 restrictions is, in the language of the review document, intended to provide an alert of an impending possible shortage and Stage 3 Restrictions would mean that just enough water is provided for use. Stage 3 restrictions includes no watering of lawn areas however garden areas may be watered within restricted hours on alternate days. Full details are available from the website. For the purposes of this analysis and reporting, the additional water needs (or supply shortfall) generally relates the additional water required to either achieve the target reliability of supply at PWSR and/or to enable restriction levels to be no worse than Stage 3. Even then these restrictions levels would only be expected a few years out of every hundred years. Under particularly severe or highly unexpected water shortage conditions, the Drought Response Plan would be triggered which could include emergency water supply measures and harsher restrictions. Occasionally, restrictions may also be required as a short-term management measure to deal with operational emergencies and incidents. Page 12

13 5. Climate Change / Variability Scenarios Central Victoria has a highly variable climate and there is no 'most likely' or 'most probable' future climate scenario. CSIRO modelling indicates that the extent and nature of climate change is unknown, so our water resource planning is built around a range of potential climate changes and potential water supply and demand futures. Based on DSE Guidelines and using CSIRO modelling, the WSDS considers five potential climate futures each with varying changes to temperature, rainfall and inflow to rivers and catchment storages. The five climate scenarios are: Scenario 1: Baseline climate. This scenario is based on a continuation of the historical climate, including rainfall and inflows, of the past 120 years from 1891 to Scenarios 2, 3 & 4: Change in future climate. This scenario set is based on a gradual increase in temperature of one degree (+1 o C) by approximately 2030 and two degree (+2 o C) by approximately The three scenarios under this set consider declining rainfall and inflow as a consequence of the increasing temperature being: Scenario 2: Wet (mild decline in rainfall and inflow); Scenario 3: Median (moderate decline in rainfall and inflow) and, Scenario 4: Dry (larger decline in rainfall and inflow). Scenario 5: Return to dry weather. This scenario is based on a return of the dry weather of 1997 to This scenario results in a greater and immediate reduction to available supply as well as an immediate increase in the demand for water. The changes to rainfall and runoff brought about by potential climate change and variability are shown in Table 3. Table 3: Climate Change Scenarios Scenario Change in Rainfall Change in Inflow Year 2030 Year 2060 Year 2030 Year 2060 S1 - Baseline climate 0% 0% 0% 0% S2 - Wet climate change -3% -5% -6% -4% S3 - Median climate change -7% -14% -16% -24% S4 - Dry climate change -7% -14% -16% -36% S5 - Return to dry weather -22% -22% -50% -50% Page 13

14 6. Demand Forecast 6.1. Current System Demand - Baseline Demand The baseline Trentham system demand for each level of water restriction is based on a detailed analysis of the last 12 years of raw water use and customer consumption as in Figure 3. Trentham System Baseline Annual Demand Annual Demand Megalitres PWSR Stage 1 Stage 2 Stage 3 Stage 4 Figure 3: Trentham annual system baseline demand. Table 4 shows the forecast water savings with water restrictions. Table 4: Water Savings with Restrictions in the Trentham System Restriction Level Approximate Saving (%) PWSR 0% Stage 1 1% Stage 2 18% Stage 3 20% Stage 4 26% 6.2. Future System Demand Future system demand had been determined by adjusting the baseline demand for population growth, future climate change and customer usage behaviour Population and Demand Growth Population growth has been determined based on reference to growth in connection numbers, the Victoria in Future (2008), census data and Local Government sources. The impact of growth on residential population and non-residential demand is considered separately as follows Residential Population Growth Trentham s residential population is forecast to grow at a rate of 1.5% per annum. Page 14

15 Non- Residential Demand Growth Trentham s commercial sector is forecast to grow at a rate of 1.5% per annum. The other sectors are forecast not to grow. Table 5 shows the classification of non-residential customers. Table 5: Classification of Non-residential Customers in the Trentham System Non-Residential Sector Portion (%) Commercial 79% Agriculture-Manufacturing-industrial 21% TOTAL 100% Total Growth in Residential and Non-residential Demand The growth in residential population combined with the growth in non-residential demand is forecast to increase the demand for raw water by 1.4% per annum. This will mean a 31% increase in demand by 2030 and a 103% increase by 2060 Table 6 shows the projected growth rates for the various customer sectors and the overall growth in demand over the next 50 years Table 6: Trentham forecast growth Adopted Growth Rate (% p.a.) Growth in Demand Trentham GroundWater Supply System Residential Agriculture, Forestry, Fishing & Mining Manufacturing Commercial Total Growth Rate (% p.a.) % 0% 1.5% 1.4% 31% 103% Environmental Demand There are no environmental water obligations with Coliban Water's Trentham surface spring water and bore water licences Climate Change Impact on Demand The analysis of the last 12 years of raw water data showed that demand increased with drier weather. Demands at year 2030 are forecast to increase with the reduced rainfall associated with climate change as shown in Table 7. Table 7: Impact of Climate Change on Rainfall and PWSR Demands Scenario Rainfall Decrease PWSR Demand Increase S3 - Median climate change -7% 4% S4 - Dry climate change -14% 9% S5 - Return to Dry -20% 17% The following Table 8 shows how the baseline demand of 105 ML is projected to increase over the next 20 to 50 years to a maximum of 123 ML at year Page 15

16 Table 8: Climate Change Demand Climate Scenario Year (ML) S1 - Baseline climate demand S2 - Wet climate change demand (no change to rainfall) S3 - Median climate change demand (7% and 14% less rainfall by 2030 & 2060 respectively) S4 - Dry climate change demand (7% and 14% less rainfall by 2030 & 2060 respectively) S5 - Return to dry weather demand (immediate 20% reduction in rainfall) 105 (+0%) % % 123 (+17%) Behaviour Change and Bounce-back 106 (+1%) 109 (+4%) 109 (+4%) 123 (+17%) 108 (+3%) 114 (+9%) 114 (+9% 123 (+17%) There are a number of factors that will potentially change the way people use water over the next 50 years. These include Permanent Water Saving Rules, water pricing, grey-water reuse, changes to garden and lawn areas, education, and continuing technological and efficiency improvements in household appliances such as dishwashers and washing machines. The adoption of PWSR is forecast to reduce water demand by 15% to 20% compared to the unrestricted supply years of the late 1990s and early 2000s. This reduction has been factored into the forecast of the current baseline demand of 105 ML. Customers have made a remarkable contribution to reducing water consumption across our region over the last 10 years and trends indicate that customers continue to be very aware of their water consumption. The extent of reductions in demand due to greater voluntary conservation measures within the community is unknown. However, communities are generally much more careful in the way they use water and it has been assumed that average household demand will decline from the current estimated usage levels by a 10% over the next 50 years with continuing behavioural change, education and technological improvements. These assumed reductions in demand are due to permanent change to the way customers use water, resulting in a permanent reduction in water use that will most likely not bounce back. The eight years of water restrictions and extremely wet year of 2010/11 reduced the raw water demand by more than 50%. This prolonged period of low water use is likely to see a continuation of suppressed demand for a number of years below the forecast system demands Improved Water Quality Any future improvement in treated water quality is not forecast to increase demand for water Summary of System Demand Impacts There are a number of influences that include population growth, climate change, behavioural change and water quality improvements that are forecast to either increase or decrease the demand for raw water over the next 20 to 50 years. These impacts are summarised as follows: 1.4% per annum growth in population and non-residential demand; 9% increase with a Median climate change; 17% immediate increase with a return to dry weather conditions; and 10% reduction in demand due to behavioural change, education and technology improvements. The overall impact of these influences is that the PWSR demand is forecast to be between a minimum of 132 ML to a maximum of 155 ML in year 2030 as shown in Table 9. Page 16

17 Table 9: Forecast Future System Demand Climate Scenario Year (ML) S1 - Baseline climate S2 - Wet climate change demand S3 - Median climate change demand S4 - Dry climate change demand S5 Return to dry weather The forecast PWSR demand are forecast to increase gradually over the next 50 years as shown in Figure 4. Annual System Demand megalitres per year Trentham System Forecast System Demand Return to Dry Demand Median climate change Demand Baseline Climate Demand Figure 4: Forecast future Trentham system demand Page 17

18 7. Supply Forecast The forecast supply is the average annual available supply (or amount of water) that sustainably available each and every year whilst meeting target levels of service General Preliminary investigations estimated the spring s annual yield at 84 ML in drought conditions, 121 ML in normal conditions, and up to 145 ML in wet years. The groundwater licence is for 48 ML with the maximum extraction in recent years of 32 ML. The minimum available supply of the Trentham supply system is 116 ML comprising 84 ML of spring water, received in drought periods, and 32 ML of groundwater. In normal to wet years, water stored in the Trentham reservoirs can be carried forward for use in following years; this ability to store water for future use effectively increases the available supply of the water supply system beyond the 116 ML. It is assumed that up to 80 ML of water can be held in the Trentham storages at the end of the season and carried forward to the next year. The Trentham groundwater system is an unconfined fractured rock-gravel aquifer that is likely to be highly sensitive to changes in rainfall. The estimates of future rainfall, as projected by the CSIRO, have been used to assess the impact of a range of possible climate futures on recharge. For unconfined aquifers in the Campaspe River basin, the median climate change is predicted to result in a decline in groundwater recharge of 23% by 2030 and a decline of 34% by This is similar to the predicted decline in surface run-off in the Campaspe River basin. As such, the estimated future availability of supply from the Trentham groundwater system is assumed to change in a similar way to the forecast changes in future Campaspe surface water availability. Computer modelling has been used to forecast the future available supply. Modelling, undertaken by the CSIRO and provided as part of the DSE WSDS Guidelines, forecasts the impact of the various potential climate scenarios on the Campaspe River basin catchment run-off and the inflow to storages. The forecast impacts on inflow are shown in Table 3. Declining inflows reduce the water available to water entitlement holders. REALM modelling, undertaken by DSE, has forecast how declining inflows impact on water availability in the Campaspe River basin, in terms of monthly water allocations, and these are assumed to reflect the availability in the Trentham system. In-house modelling has then been used to analyse the forecast monthly allocations and to determine how they specifically meet the current and forecast system water demands. The analysis determines for each climate scenario the: Supply Reliability Frequency of water restrictions Severity of water restrictions; and Additional water needs to meet the target Levels of Service (both additional temporary water and permanent water needs) Modelling also allows for the analysis of the sensitivity of a number of variables to determine what factors have the greatest impacts the supply-demand balance. Variables and their current values (shown in brackets) include: Maximum allocation (100% or 177 ML comprising maximum spring water and groundwater extraction) Minimum allocation (66% or 116 ML comprising minimum spring water and groundwater extraction) Carryover limits (45% or 80 ML) Carryover loss (5% due to evaporation) System Demand (105 ML increasing to 224 ML at year 2060) Growth (1.4% per annum) Page 18

19 Behavioural change in consumption patterns (10% reduction in demand over 50 years) Level of Service (95% supply reliability with water restrictions no more severe than Stage 3) Forecast supply for the Trentham system is shown in Table 10. Table 10: Forecast Future Supply Climate Scenario Year (ML) S1 - Baseline climate S2 - Wet climate change S3 - Median climate change S4 - Dry climate change S5 - Return to dry weather Figure 5 shows the variation in forecast supply over the next 50 years Available Supply megalitres per year Trentham System Forecast System Supply FORECAST AVAILABLE SUPPLY RANGE Climate Change Supply Baseline Climate Change Supply Return to Dry Supply Figure 5: Forecast Supply for the Trentham system 7.2. Catchment Management Coliban Water has an interest in the catchment land that supports the water resource for the Coliban Water Trentham storages and groundwater bores. The performance of these spring and groundwater catchments in terms of spring yield and groundwater availability for extraction can be varied by changes in the amounts and timing of rainfall and infiltration as well as potentially by the level and type of development of the catchment. Coliban Water should continue to manage and support, within the means that it has to do so through the planning process, only proper and orderly development within the catchment to protect raw water supply. This could be through available planning and policy channels and funding initiatives. These could include the likes of catchment protection guidelines, joint working with neighbouring water businesses and our local catchment management authorities, implementing State planning policy frameworks, participating in local planning policy reviews and the funding of catchment management programs. Page 19

20 8. System Performance Evaluation The performance of the Campaspe system is measured on its ability to supply future demand and the target levels of service. The performance measures that are evaluated are: supply reliability with a target of at least 95% whereby the likelihood of water restrictions is no more than 5 years in 100 years; and water restriction levels with a target of no worse than Stage 3 By comparing the forecast supply and demand it is possible to estimate the shortfall in available supply and when this may occur. The forecast supply and demand for the climate change scenarios are shown in Figure 7. The Trentham system is forecast to perform satisfactorily for the 10 to 15 years with the WSDS reviewed every 5-years to take into account changes in climate or population growth that may pose a risk to meeting demand. The forecast supply and demand for the climate change scenarios are shown in Figure Trentham System Forecast System Supply and Demand Supply ML per year FORECAST AVAILABLE SUPPLY RANGE FORECAST DEMAND RETURN TO DRY SUPPLY Climate Change Supply Supply with Median Climate Change Return to Dry Supply Demand with Median Climate Change Figure 6: Forecast Supply and Demand Trentham System Figure 6 shows that the forecast demand increases gradually from the current 105 ML to exceed the forecast median climate supply from about the year Additional supply is required beyond the year 2030 to a maximum of 74 ML by year 2060 to meet expected demand and levels of service. However, a return to dry conditions would result in a shortfall in supply of approximately 30 ML at year 2030 increasing to approximately 100 ML by year The shortfall in available supply over the next 50 years and the forecast supply reliability are shown in Table 12. Table 12: Shortfall in the Supply-Demand Balance and Supply Reliability Year 2011 Year 2030 Year 2060 Climate Scenario Supply Supply Supply Shortfall Shortfall Shortfall Reliability Reliability Reliability S1 - Baseline climate Nil 100% Nil 98% 50 ML 0% S3 - Median climate change Nil 100% Nil 94% 70 ML 0% S5 - Return to dry weather Nil 100% 30 ML 30% 100 ML 2% Page 20

21 Figure 7 shows the supply reliability, and supply shortfalls, over the next 50 years for the median climate change scenario. At year 2030 the supply reliability is forecast to be 94%, just below the target level of 95% and requiring Stage 2 water restrictions. The supply reliability falls away beyond the year 2030 where water restrictions would be continually required at 2060; additional water is required in order to meet service level that could be either be an annual amount of 74 ML of temporary water or a one-off additional amount of permanent water shares of approximately 130 ML. Trentham System Reliability (Median Climate Change) Reliability of PWSR 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 95% Target Reliability Forecast Reliability median climate change Target Reliability Median Climate Change Scenario Year 2011 Year 2030 Year 2060 Reliability of PWSR Supply 100% 94% 0% Frequency of Water Restrictions Nil 6 years in 100 Every Year Reliability meets Target Level of Service (LOS) Yes No No Levels of Water Restrictions Nil Stage 2 Worse than Stage 4 Minimum Supply meets Target Level of Service (LOS) Shortfall in Available Supply in Restriction Years Permanent Water Needed to meet Level of Service (LOS) Temporary Water Needed in Restriction Years to meet LOS Figure 7: Forecast Supply Reliability Yes Yes No Nil 5 ML 74 ML Nil 10 ML 130 ML Nil 5 ML 74 ML (Every year) Page 21

22 9. Demand Reduction Measures Coliban Water will continue to work with the community and pursue efficiency measures within the Trentham system to achieve demand reduction which can be permanent or temporary in nature. Demand reduction measures that provide on-going and continuous improvement to water reliability are described below.. These demand reduction measures have been considered in the development of the WSDS and formulation of system demands Permanent Water Saving Rules (PWSR) PWSR were introduced by the Victorian Government in March 2005 and came into force in the Trentham system from July through to December PWSR again came into force at Trentham from October 2007 following the lifting of water restrictions. The rules are designed to have customers permanently conserve water by requiring them to adopt some basic common sense water conservation measures. It is expected that PWSR will reduce 'unrestricted' demand, as experienced in the late 1990s, by almost 30%. An allowance of approximately 29% was factored into the assessment of the future Trentham system demand. The extent of actual water savings attributable to PWSR will be better understood with the evaluation of demand over the next four to five years Reduction of Operational Water Over the last four years, operational water accounted for 28% of the raw water extracted from the Trentham supply. Two-thirds of non-revenue water is required in the operation of the Trentham water treatment plant where regular filter cleaning is necessary in the water treatment process. At this stage, it is assumed that there are no savings in treatment plant process operational water. The other third of operational water is lost in the operation of the water distribution system. To address water distribution losses and to ensure that water distribution system efficiencies are maintained and improved where possible, Coliban Water will continue its leakage reduction and water main replacement programs to replace old mains that are susceptible to or experiencing bursts and leaks Water Saving Incentives and Community Education A number of water saving incentives and education programs have been in place during the last five years to achieve permanent behavioural change in community water consumption. Incentives and scheme have included the fitting of efficient water fixtures- such as low-flow shower roses and taps- in new dwellings and the water-efficiency labelling of water using appliances such as washing machines. Other schemes have provided rebates for households and organisations involved in water smart programs such as the retro fitting of existing dwellings and the maintenance of efficient garden irrigation systems. These programs and other options such as grey-water re-use, installation of rain water tanks, continued improvement in the efficiency of appliances and fixtures are expected to continue to change the behaviour and volumes of community water consumption. A 10% reduction in demand, spread over the next 50 years, has been assumed in the water demand projections for these continued water efficiency savings Pricing Incentives Increases in the customer's water price can have an influence on reducing consumption. Price increases implemented over the last ten years may have influenced customer behaviour and thereby reduced overall demand. Similarly, any future price increases could be expected to further reduce demand. Any demand reductions that do occur are considered to be included as part of the 10% reduction in demand as outlined in the above Water Saving Incentives and Community Education programs. Page 22

23 9.5. Summary of Demand Reduction Measures The above demand reduction measures and their estimated water savings have been considered elsewhere in the WSDS and no more additional water savings are assumed. Page 23

24 10. Additional Supply Measures Permanent Water Market (where available) The surface water and groundwater in the Trentham area are not from regulated systems and as such Coliban would likely have difficulty securing additional water. Table 14 shows the amount of permanent water, say in the form of additional groundwater licence, required to ensure the target levels of service of 95% supply reliability and a minimum level of service of Stage 3 water restrictions are achieved. Table 14: Permanent Water needs to achieve Target Levels of Service Climate Scenario Year 2011 Year 2030 Year 2060 S1 - Baseline climate Nil Nil 63 ML S3 - Median climate change Nil 10 ML 130 ML S5 - Return to dry weather Nil 45 ML 150 ML Over the next 20 years the supply reliability for the baseline climate and median climate change scenarios is at least 94% which means that at worst the permanent water is only required in six years in 100 years; in all other years the permanent water is unused and in effect it would be spilt and lost. This option would therefore be an inefficient use of water resources and not cost effective. However beyond 2030 an additional permanent water source is necessary to avoid on-going water restrictions Temporary Water Market (where available) The purchase of temporary water is an appropriate response if water shortages are likely to be infrequent and where temporary water is available. However neither the surface water nor groundwater in the Trentham area is from a regulated system and as such Coliban Water is not able to secure allocations water. The Trentham system has a forecast supply reliability of 94% at year 2030 with water restrictions in six years out of 100 years. In these circumstances, the purchase of temporary water is only required in those years when water restrictions are worse than Stage 3. Where temporary water trade exists, the major drawback is the potential lack of availability of temporary water in times of water shortages. Table 15 shows the amount of temporary water required, should it be available, to ensure the target levels of service of 95% supply reliability and a minimum level of service of Stage 3 water restrictions are achieved. Table 15: Temporary Water needs to achieve Target Levels of Service Climate Scenario Year 2011 Year 2030 Year 2060 S1 - Baseline climate Nil Nil 45 ML S3 - Median climate change Nil 2 ML 71 ML S5 - Return to dry weather Nil 29 ML 96 ML At year 2030, the supply reliability of greater than 94% for the baseline climate and median climate change scenarios means that at worst temporary water is only required in six years in 100 years; in all other years it would be unnecessary to purchase temporary water Groundwater Coliban Water has two existing groundwater bores licences. At present only one bore is operational and we are unable to access our full entitlement of 48 ML/year. In order to be able to extract the full entitlement of 48 ML, the second groundwater bore needs to be brought into operation. This would also provide operational redundancy. Page 24

25 The groundwater in the Trentham area is not covered by a Groundwater Management Area and as such licences in the area are not tradable and any new license request requires application and detailed assessment of sustainability and impact on third parties. Depending on the yield from each bore, a bore field of 5 to 9 additional bores could secure the Trentham water supply to Each bore would need to be located likely at least 1.5 km apart and away from existing bore licenses to limit impacts on the groundwater and other users Connect to Fern Hill Storages Trentham could be connected to the Fern Hill storages by an approximate 12 kilometre pipeline and other ancillary works. The now decommissioned Fern Hill storages (Nos 1. and 2.) are located to the south of Tylden approximately three quarters of the way from Trentham to Tylden. Constructed in 1883 and 1930 respectively they currently have a combined capacity of 118 ML. Fern Hill storages previously supplied the township of Tylden prior to its connection to the Kyneton system. The storages have been partially decommissioned by reducing their volume Connect to Tylden This option would involve the connection of Trentham to Tylden by an approximate 16 kilometre long pipeline. This option would improve the reliability of supply to Trentham as it would be connected to a much bigger system. Infrastructure augmentations may also be required between Kyneton and Tylden Additional Water Private Rain Water tanks At present, recommendations from the Department of Health is that water for potable purposes should come from a reticulated potable supply where one is available rather than from rainwater tanks. Many households in the Trentham system most likely use rain-water tanks for non-potable purposes which effectively reduce the demand on the potable system. A restriction relating to rain water tanks is that they are reliant on local rainfall and shortages of tank water associated with low rainfall are highly likely to coincide with any shortage that may occur in the Trentham groundwater system. To be effective in significantly reducing potable demand, rainwater tanks have to be of a larger size and appropriately used. Tanks and plumbing associated with such systems are also expensive Alternative Water Sources An Alternative Water Atlas is being compiled that will identify and communicate potential sources of alternative water that may form part of the future supply-demand balance. The objectives of the Alternative Water Atlas from the Water Supply Demand Strategy Guidelines (DSE, 2011) are to: Identify the volumes of stormwater, recycled water and other alternative water sources available within the works of the Corporation (including wetlands and retardation basins) and/or local council; Help to inform future opportunities for the use of treated stormwater, recycled water and other alternative water sources in the control of either a water corporation or local council; Some of the alternative sources identified through the development of the Alternative Water Atlas are included in the assessment of options where a supply-demand shortfall exists. Page 25

26 11. Water Quality Measures The water treatment plants within the Trentham system are generally able to meet required customer water quality standards, even when the source water is of poorer quality than normal such as through the recent dry period. The Department of Health is also increasing the standards it expects for treated water quality including meeting a TDS (salinity) level of no more than 500 mg/l by The Trentham system WTPs will not require upgrades to achieve required water quality standards into the future. Page 26

27 12. Options Analysis Demand Reduction Demand reduction measures as listed in section 9 are in progress and have been taken into account in the forecast future demands. These include an estimated 10% reduction in household consumption spread over the next 50 years due to permanent changes in customer consumption behaviour and the implementation of future technologies Additional Water A water market does not exist so cannot be used to purchase temporary water allocation to meet any supply shortfall should one arise Options Summary The long list of options to address possible future water needs is attached as Appendix 2. Table 13 details those options that have been short-listed as the preferred options to meet future shortfall in demand over the next 50 years based on a consideration of the social, environmental and economic costs and benefits. Table 13: Water Supply Strategy Trentham system Trentham System Short List Options Strategy Source of Additional Water Item Project Reduce Operational water Shortfall at Year 2060 Median Climate Change (ML) Implemented and Committed Projects Return to Dry (ML) Additional Supply Demand Balance Benefit to 2 ML by year 2030 Project Summary Already Implemented Already Committed Project Status Ongoing; to maintain and improve system efficiency Total Additional Water 2 2 Other Projects 10.4 Groundwater Up to 100 ML Up to 100 ML 16 ML per year (by year 2018) 100 ML (by year 2060) 10.5 Connect Trentham to Fern Hill Reservoirs 10.6 Connect Trentham to Tylden Up to 100 ML Up to 100 ML Estimated 100 ML per year (to be determined) Up to 200 ML Up to 200 ML Supply total water needs of Trentham Cost Benefit/ Cost (ML/$1m) Project Status < $45, Upgrade existing groundwater bores. Extend bore field. 50 Concept Only < $85, Concept Only Total Additional Water Based on the above, the priorities for future additional supply, if required would be; 1. Reinstate the second groundwater bore; and 2. Investigate options for additional supply that include: a. Additional groundwater bores b. Connection to the Fern Hill storages c. Connection to Tylden (Kyneton) system Page 27

28 13. Management of Risk and Uncertainty General Having multiple and redundant supply sources minimises risk. The dual supply for Trentham of the spring water plus the groundwater provides good security and this security will be further enhanced once a second bore is operational at Trentham Murray Darling Basin Plan The Murray Darling Basin Authority has responsibility for developing the Murray Darling Basin Plan, which will guide the management of water resources across the Basin s four states and one territory. The Plan builds on and complements previous water reforms and contributes to the Authority s vision for a healthy working Basin. The Basin Plan aims to balance the water needs of the environment and other uses, through the establishment of new limits (known as sustainable diversion limits, or SDLs) on the volumes of water use in systems and regions. The draft Basin Plan identifies the following additional water needs to be recovered for southern catchments relevant to Coliban Water s systems: Wimmera-Avoca 23 GL Campaspe 12 GL Loddon 10 GL Murray 63 GL (This volume is expected to be met through NVIRP 2) Goulburn-Broken 99 GL (This volume is expected to be met through NVIRP 2) However, to meet the needs of the River Murray, a further 971 GL needs to be recovered. This volume would need to be recovered from somewhere within the southern Basin catchments that regularly flow into the Murray and there is flexibility as to where this water comes from. Coliban Water would likely only be affected by Basin Plan implications in the irregular times that it wishes to access the market to supplement low allocations or reservoir inflows. Due to the very small fraction of total system water that Coliban Water would be seeking, it is reasonable to assume that in all but the worst scenarios that there would be at least some water available. There is some risk relating to how much of the 971 GL may be sought from the smaller catchments upon which Coliban Water relies and what may happen if the proposed Murray- Darling Basin Authority voluntary buy-back process does not achieve the targeted volumes. From Coliban Water s perspective, the Campaspe and Loddon systems may be the catchments of greater concern to be more closely monitored into the future. Most of the aspects of the Basin Plan are presently not intended to take effect in Victoria until 2019 and as such there is time to monitor, contribute to and further assess the likely future impacts of the Basin Plan over the next couple of years. Water Supply Demand Strategies are next due for renewal in 2017 which will be the appropriate time to incorporate any required changes. Page 28

29 14. Proposed Actions Trentham System The WSDS proposes the following actions for the Trentham system Short-term Actions The actions proposed for the period covered by WaterPlan 3 (2013 to 2018) and WaterPlan 4 (2018 to 2023): Coliban Water should continue to manage and support, within the means that it has to do so through the planning process, only proper and orderly development within the catchment to protect raw water supply; Continue with the main replacement and leakage detection programs to minimise nonrevenue water; Investigate and accurately determine the supply available from the Trentham spring surface water supply; Reinstate the second groundwater bore; Investigate options for the additional long-term supply to Trentham that include: o o Additional groundwater bores Connection to the Fern Hill storages o Connection to Tylden (Kyneton) system Long-term Actions The actions proposed for the period to 2060: Coliban Water should continue to manage and support, within the means that it has to do so through the planning process, only proper and orderly development within the catchment to protect raw water supply. Continue with the main replacement and leakage detection programs to minimise nonrevenue water Connect Trentham to new source of water supply Page 29

30 15. Community & Stakeholder Engagement The Water Supply Demand Strategies are key strategies for a water business that guide the level of service to our customers and drive augmentation works to enable us to have available required supplies to meet demands. We recognise the importance of implementing a community engagement program that: Inspires confidence in the process and our ability to manage water resources now and into the future; Promotes acceptance and understanding of our plans; and Provides information that supports communities understanding and ability to have informed input. Some of the methods that have been utilised in engagement around the development and finalisation of this WSDS, or have fed into the WSDS, were: 2009 region wide Understanding our residential customer research project. This included focus groups and mail survey with willingness to pay a key focus; 2011 surveys sent to all 66,000 residential customers and 5,000 non-residential customers; Attended and presented to community groups upon request; Held public meetings in the Loddon system which had been particularly heavily impacted through the drought; Meetings with individuals and groups who came forward offering suggestions and comments relating to particular systems and towns; Website posting of a five year progress review of WaterPlan 2055 (Coliban Water s 2005 WSDS); Website posting of draft strategies requesting comments and feedback; Direct mail to almost 100 key stakeholders directing them to the website and requesting comments and feedback; Sending out hardcopies of the WSDS draft reports upon request; Presentations to Coliban Water staff of draft strategies requesting comments and feedback; and Presentations and strategy sessions with the Coliban Water Board leading up to WSDS endorsement. The feedback received and conversations had have been useful in informing development and in finalisation of our WSDS. There have been no major issues or suggestions raised significantly affecting the outcomes and recommendations of the WSDS with feedback received suggesting a high level of support for the direction proposed by Coliban Water and articulated through the strategies. Page 30

31 APPENDIX 1 Alternative Water Atlas Trentham System Summary Page 31

32