Buchan Water Supply Demand Strategy Buchan Water Supply Demand Strategy AECOM

11 May 2010

Buchan Water Supply Demand Strategy

60144336 Task 1.04

Prepared by

AECOM Australia Pty Ltd Level 9, 8 Exhibition Street, Melbourne VIC 3000, Australia T +61 3 9653 1234 F +61 3 9654 7117 www.aecom.com ABN 20 093 846 925

11 May 2010

60144336

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Quality Information

Document Buchan Water Supply Demand Strategy

Ref 60144336

Date 11 May 2010

Prepared by M Habener

Reviewed by S Wallner / L Dragicevich

Revision History

Authorised Revision Revision Details Date Name/Position Signature

A 12-Apr-2010 Initial Draft A Grant Original Signed Principal Engineer - Water B 11-May- Final Issue A Grant Original Signed 2010 Principal Engineer - Water

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Table of Contents Executive Summary i 1.0 Introduction 1 1.1 Regional Setting 1 2.0 Current Water Supplies 3 2.1 Description of Water Supply System 3 2.1.1 Overview 3 2.1.2 Buchan River 3 2.1.3 Diversion 4 2.1.4 Treated Water Storage 4 2.1.5 Treatment 4 2.1.6 Buchan Caves Spring 4 2.1.7 Standpipe 4 2.2 Allocations of Water 4 2.2.1 Bulk Entitlements 4 2.2.2 Licensed Diversions 5 2.2.3 Groundwater Licences 5 2.2.4 Level of Service Objectives 5 2.3 Historical Water Restrictions 6 3.0 Previous Studies, Legislation and Regulation 7 3.1 Previous Long Term Planning Studies 7 3.1.1 Drought Response Plan for Buchan (SKM, 2006) 7 3.1.2 EGW Water Supply Demand Strategy (SKM, 2007) 7 3.2 Regulations and Legislation 7 4.0 Water Demand 10 4.1 Current Demand 10 4.1.1 Previous Demand Estimates 10 4.1.2 Seasonal Pattern of Demand 10 4.1.3 Bulk water meter data and historical diversions 12 4.1.4 Customer Billing Data 13 4.1.5 Commercial and Industrial Water Use 13 4.1.6 Unaccounted Water 13 4.1.7 Summary of Current Demand 14 4.2 Forecast Water Demand 14 4.2.1 Previous Population Projections 14 4.2.2 Recent Census Data 14 4.2.3 Victoria in Future Data 14 4.2.4 Summary of Population Projections 15 5.0 Demand Management and Reduction 16 5.1 Measures to Achieve Demand Reduction Targets 16 5.1.1 Current Demand Reduction Initiatives (SKM, 2007) 16 5.1.2 Future Demand Reduction Initiatives (SKM, 2007) 17 6.0 Water Supply 19 6.1 Future Reliability of Surface Water 19 6.1.1 Impact of Climate Change 19 6.1.2 Step Change 19 6.2 Impact of Bushfires 20 6.2.1 Previous Bushfires 20 6.2.2 Proposed Fuel Reduction 21 6.3 Forestry 21 6.4 Future Streamflow Projections 21 7.0 Reliability of Supply 23 7.1.1 Method Overview 23 7.1.2 Modelling Assumptions 23 7.2 Current Reliability of Supply 24 7.3 Future Reliability of Supply 27

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7.3.1 Year 2030 27 7.3.2 Year 2060 29 7.3.3 Summary 31 8.0 Management of Water Supply 32 8.1 Water Loss Reduction 32 8.2 Water Carting 32 8.3 Buchan Caves 32 8.4 Groundwater 32 8.5 Recommendations for Managing Supply 33 9.0 Stakeholder Consultation 34 10.0 Conclusions and Recommendations 35 10.1 Conclusions 35 10.2 Summary of Recommendations 35 11.0 References 36

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Executive Summary Water Supply Demand Strategies (WSDS) aim to ensure that an appropriate balance is maintained between urban water supply and demand over the long term planning horizon of 50 years. East Gippsland Water (EGW) finalised their WSDS for all water supply systems during 2007 and is now in the process of reviewing these strategies in light of updated climate change, growth and bushfire information. AECOM Australia Pty Ltd (AECOM) has been engaged by EGW to revise the existing WSDS for the Buchan water supply system. This revised WSDS will replace the strategy set out for Buchan in EGW’s overall WSDS (Section 7). EGW has set level of service (LOS) objectives for water supply reliability. The objectives state that: x Moderate restrictions (Stages 1 & 2) are not desired more frequently on average than 1 year in 10 x More severe restrictions (Stages 3 & 4) are not desired more frequently than 1 year in 15.

The LOS objectives have been used as a basis for assessing the adequacy of Buchan’s current water supply system for meeting current and future water demand. Recent studies and observations have shown that the impacts of climate change and bushfires on streamflow availability in the Buchan water supply catchment will be significant. To assess EGW’s ability to meet LOS objectives under these changing conditions REALM modelling was undertaken. This modelling investigated three key scenarios: x 2010 (Current ) - step change climate estimates with current bushfire impact and Victoria In Future (VIF) growth x 2030 - when the impacts of climate change and bushfire are most significant (assumes a step change in climate, full bushfire impact and VIF growth) x 2060 - at the end of the planning horizon (assumes step change in climate change, moderate bushfire impact and VIF growth)

The level of service provided under each scenario is shown as follows:

Scenario Level of Service Objectives Voluntary Stage 2 Stage 4 Current Situation 1 in 62 years N/A 1 in 62 years 2030 1 in 12 years 1 in 20 years 1 in 31 years 2060 1 in 20 years 1 in 62 years 1 in 62 years

It can be seen from the above table that Buchan’s water supply system will continue to be very reliable in terms of EGW’s ability to meet LOS objectives. Daily flow data recorded at Buchan (Gauge 222206A) shows that there has only been one day in the last 62 years where EGW has been unable to extract their full entitlement of 1.05 ML/day. Given that available supply at Buchan should exceed demand over the next 50 years even after considering the impacts of climate change, past bushfires and growth in water demand, further supply enhancement will not be required. The greatest risk to Buchan’s water supply system is deterioration in water quality due to impacts such as bushfire. A number of alternative supply options were assessed to ensure continuity of supply during such emergencies. From this assessment the most suitable alternative was determined to be emergency water carting.

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In conclusion, it is recommended that EGW implement the following action plan: Action Implementation Update Buchan’s Drought Response Plan. This plan Immediate should document the drought response options outlined in Section 8.0. Continue to monitor and strive to reduce losses within Ongoing the water supply system Continue to implement demand reduction strategies to Ongoing assist in achieving EGW”s demand reduction targets (8% reduction in per capita demand by 2020) Continue to monitor the impacts of logging and if long Ongoing term supply diminishes seek a reduction in the area to be logged within the water supply catchment Undertake a water audit for the high water users Longer term

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1.0 Introduction Water Supply Demand Strategies (WSDS) aim to ensure that an appropriate balance is maintained between urban water supply and demand, over a long term planning horizon of 50 years. East Gippsland Water (EGW) finalised their WSDS for all water supply systems during 2007 and is in the process of reviewing each of the water supply strategies. The revision of the WSDS will be based upon new information relating to climate change, drought, bushfires, growth and their combined impacts. WSDSs are otherwise required to be reviewed and updated at least every 5 years. Continuing dry conditions have resulted in a significant drop in streamflow across Victoria and East Gippsland has not been exempt from these impacts. CSIRO have determined that climatic conditions are tracking above the previous high climate change scenarios, which suggests that the medium climate change scenario that was recommended by Department of Sustainability and Environment (DSE) during preparations of the earlier WSDSs may over estimate long term yields. The previous WSDS for Buchan recommended that EGW: x Reduce the level of uncertainty in the current and future water demand estimates x Continue to pursue additional demand reduction options x Obtain legal certainly to access water in the natural spring at the Buchan Caves Reserve x Manage the long term impacts associated with the 2003 bushfires.

In accordance with the WSDS review process, this document forms a revised WSDS for the Buchan water supply system and will replace the strategy set out in EGW’s overall WSDS (Section 7). Where possible this strategy has been prepared in accordance with the DSE’s Guidelines for the Development of a Water Supply Demand Strategy (DSE, 2005), however it is recognised that some of these guidelines are now out of date, particularly with regard to climate change.

1.1 Regional Setting Buchan is a small town at the centre of a sheep, cattle and timber area, located 80 km north-east of Bairnsdale and 340 km east of Melbourne. The town is located on the banks of the Buchan River and is well known for the Limestone Buchan Caves. The 2006 census showed that Buchan and the surrounding area had a population of around 326. The location of Buchan is shown in Figure 1.

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Figure 1: Regional Map (Google, 2010)

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2.0 Current Water Supplies

2.1 Description of Water Supply System 2.1.1 Overview Buchan’s water supply comes from a pumping pool on the Buchan River that was created by the construction of a log barrier in 1983. The pumping station has the capacity to transfer 12.1 L/sec (or 1.05 ML/day) of raw water to the Water Treatment Plant (WTP). From the WTP, water is pumped to 14 x 45kL interconnected balancing tanks (soon to be replaced by a single 1 ML treated water storage) where it is held, disinfected then gravity fed to the town’s reticulation system. A schematic of the Buchan water supply system can be seen in Figure 2 with further details on the key components provided in Sections 2.1.2 to 2.1.7.

Figure 2: Buchan Water Supply System

2.1.2 Buchan River The Buchan River water supply catchment covers an area of approximately 780 km2. The town of Buchan sits at the bottom of the water supply catchment. Upstream of the town’s offtake, the catchment is predominantly native forest although cleared agricultural land surrounds the town. SKM (2009) stated that the vegetation types within the catchment consist of ash, mixed eucalypt and snow gum (95%) and grassland areas (5%). In the vicinity of Buchan the river is around 20 m wide, with riffles to 60 cm and pools to 200cm deep (DPI, 2010). Downstream of Buchan, the river joins with the Murrindal River before joining the Snowy River a further 3 km downstream.

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2.1.3 Diversion SKM (2007) stated that: “A 300-450mm high log barrier, constructed in January 1983 provides 2.34 ML of storage on the river. Eighty percent of this storage or 1.87ML is assumed to be unusable”. This is the only raw water storage available to the Buchan Water Supply System. The pumping station upstream of the log barrier has the capacity to transfer 12.1 L/sec (or 1.05ML/day) of raw water to the WTP.

2.1.4 Treated Water Storage Buchan’s treated water storage currently consists of 14 interconnected 45 kL concrete balancing tanks. In total there is a capacity of 0.63 ML. A new 1 ML storage tank is currently being designed to replace 11 of the existing tanks. This is due to be completed in 2010 and will provide an additional 80% treated water storage volume.

2.1.5 Treatment During late 2007, EGW commissioned a new WTP at Buchan to improve the quality of treated water provided to the town. The treatment plant uses a Dissolves Air Flotation Filtration (DAFF) process, which is capable of treating raw water from the Buchan River to a standard of less than 0.3 NTU (Turbidity) and less than 5 Pt/Co (Colour). The treatment plant has been designed with a treatment capacity of 8 L/sec giving a total daily volume of 0.6 ML/day. Prior to the commissioning of the treatment plant, water was pumped from a pumping pool on the Buchan River and disinfected with sodium hypochlorite.

2.1.6 Buchan Caves Spring During high turbidity events on the Buchan River, EGW previously sourced water from a natural spring located further upstream of the Buchan River offtake near the Caves. The water from the spring was considered to be too hard for use (except during extreme drought conditions) and was found to cause issues with customer’s hot water systems. As a result it is highly unlikely that this spring will be used again in the future (with the exception of emergency situations).

2.1.7 Standpipe During April 2009, EGW brought a standpipe back into service to supply residents in the Buchan area who are not connected to the reticulated water supply. The water delivered by the standpipe is of drinking water quality and is available to both commercial water carters and residents. The standpipe is located on the Buchan Orbost Road just outside of the Buchan Recreation Reserve (EGW, 2009).

2.2 Allocations of Water 2.2.1 Bulk Entitlements East Gippsland Water has a bulk water entitlement of 170 ML per year for the Buchan River, which is subject to the following flow sharing arrangements: x When the flow is less than or equal to 1.05 ML/day then EGW’s entitlement is equal to the flow in the Buchan River upstream of the town off-take x When the flow is above 1.05 ML/day then EGW’s entitlement is 1.05 ML/day.

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This entitlement was outlined in the Victorian Government Gazette on the 4 September 1997; this can be seen at: http://gazette.slv.vic.gov.au/view.cgi?year=1997&class=general&page_num=2349&state=V&classNum=G35&sea rchCode=782811\

2.2.2 Licensed Diversions Southern Rural Water (SRW) provides an overview of local management rules for each of their river catchments on a regular basis. The latest revision of these rules was issued in September 2009. The management rules not only provide operational guidelines, but also a summary of licences held. A summary of licences held for the Buchan River, which is part of the Snowy River Catchment, is shown in Table 1.

Table 1: Number and Volume of Licences issued for the Buchan River (SRW, 2009) Number of Annual Volume licences (ML) Direct Pumping 7 569.2 Domestic and Stock Licences 3 6.6 Bulk Entitlements (EGW) 1 170 Commercial 1 2.2 Total 12 748

From Table 1 it can be seen that the volume of water available to private diverters on the Buchan River is 578 ML/annum. EGW makes up the remaining licensed volume of 170 ML/annum with their Bulk Entitlement. Within the ‘Local Management Rules’ for the Snowy River Catchment SRW (2009) states: “A simple roster applies to irrigators on the Buchan River. Currently there are only 3 active licences. Restrictions are invoked when stream flows fall below 10ML/day at the Buchan 222206A gauge site. Two irrigators only are allowed on per day with restricted hours. Total Ban on the Buchan River occurs when stream flow falls below 4ML/day on the downstream side of the town offtake (at the Buchan River bridge)”. This indicates that EGW’s surface water supply for Buchan should not be comprised by upstream diversions during low flow periods.

2.2.3 Groundwater Licences EGW do not directly extract groundwater to supply the Buchan water supply system, therefore no groundwater licences are held.

2.2.4 Level of Service Objectives EGW has previously defined the following level of service objectives for water supply reliability: x Moderate restrictions (Stages 1 & 2) are not desired more frequently on average than 1 year in 10 x More severe restrictions (Stages 3 & 4) are not desired more frequently than 1 year in 15.

Further information on allowed uses under each stage of water restrictions is provided at: http://www.egwater.vic.gov.au/Water/WaterRestrictions/tabid/95/Default.aspx Buchan is currently subject to Permanent Water Saving Rules, which are being applied as part of a Victoria wide strategy.

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2.3 Historical Water Restrictions A search of EGW’s archives found the following historical events relating to changes in water restrictions for Buchan: x 8 February 1983 – Stage 3 restrictions introduced x Date Unknown – restrictions lifted x January 2003 – Voluntary restrictions introduced x 12 March 2003 – Stage 3 restrictions introduced (due to water quality issues rather than water shortage) x May 2003 – Stage 3 restrictions eased to Stage 2 restrictions x July 2005 – Water restrictions removed

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3.0 Previous Studies, Legislation and Regulation

3.1 Previous Long Term Planning Studies A number of long term planning reports have been commissioned by EGW (and their predecessors) relating to water supply security. The key documents include: x Drought Response Plan for Buchan, SKM (2006) x Water Supply Demand Strategy, SKM (2007).

The reports are summarised in the following sections.

3.1.1 Drought Response Plan for Buchan (SKM, 2006) Under section 78B and 78C of the Water Industry Act (1994) all water corporations holding a retail water licence are required to develop a Drought Response Plan (DRP) for approval by the Minister. The DRP for Buchan aims to provide a framework for ensuring a timely and effective response to water shortages to ensure that social, environmental and economic impacts of shortages are reduced. The DRP included modelling of Buchan’s water supply system which was used as a basis for the preparation of the initial WSDS in 2007.

3.1.2 EGW Water Supply Demand Strategy (SKM, 2007) The WSDS prepared by SKM in 2007 is EGW’s current WSDS for all of its water supply systems and forms the basis from which this updated WSDS has been developed. The previous WSDS provides long term strategies for managing available urban bulk water supply and customer demand across each of EGW’s water supply systems.

3.2 Regulations and Legislation Surface Water Caps Each Surface Water Management Area (SWMA) within Victoria is subject to a surface water cap. Buchan falls within the Snowy River SWMA which was listed as being slightly modified during a 2005 assessment. The Snowy River basin is capped at current diversions which are roughly equivalent to 6320 ML. Any further development in terms of surface water can only be undertaken by trading water rights (via water savings achieved through improvements in distribution and water-use efficiency) or via use of alternative sources of water (e.g. recycled water).

Groundwater Caps Groundwater management in Victoria is undertaken geographically through the identification of a series of areas called Groundwater Management Units (GMU’s). The groundwater management areas in East Gippsland can be seen in Figure 3 The three different groundwater units are: x Groundwater Management Area (GMA) – these cover aquifers with high use of potential for high use to ensure sustainable extraction. Each GMA has been assigned a cap known as Permissible Annual Volume (PAV) x Water Supply Protection Area (WSPA) – these cover aquifers that have been identified as having potential value however does not yet require a PAV to be set. Each WSPA has a Groundwater Management Plan to ensure the ongoing protection of the resource x Unincorporated Areas (UA’s) – these cover aquifers where groundwater is expected to provide little potential due to low yields or poor water quality.

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Buchan is located within an Unincorporated Area and therefore no caps on groundwater use have been established.

Figure 3: Groundwater Management Units in East Gippsland (Red: WSPA, Blue: GMA, Orange: UA)

(Source http://gmu.geomatic.com.au/Default.aspx)

Streamflow management plans Streamflow Management Plans (SMP’s) aim to ensure that surface water is managed in a fair, reliable and equitable manner between both consumers and the environment. They define the rules for sharing water in unregulated rivers and streams and are only developed for priority streams where there are competing water users. The Buchan River is classified as being a ‘regulated river’ therefore no SMP is applicable.

Regional River Health Strategy Stream value for the Buchan River is covered by the East Gippsland Catchment Management Authority Regional River Health Strategy (EGCMA RRHS). The Buchan River is classified as being in ‘good’ condition within the RRHS; it is also listed as being a river with high heritage value. A number of strategies have been set within the RRHS to ensure that the condition of each waterway is maintained or improved in a way that protects the identified values.

Heritage Rivers The Heritage Rivers Act (HRA) identifies a number of Heritage River Areas within Victoria. The HRA prohibits some water-related activities in heritage river areas, including the construction of artificial barriers or structures that may impact on the natural passage of flow. The HRA also restricts and in some cases prohibits the diversion of water, some clearing practices, plantation establishments and domestic animal grazing.

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The upper reaches of the Buchan River is listed as a Heritage River Area and is subject to the restrictions of the HRA.

Victorian River Health Strategy The Victorian River Health Strategy (VRHS) outlines the Government’s long-term policy for managing Victoria’s rivers. It includes a vision for Victorian river management, policy direction on river health issues and a blueprint to integrate all work on Victorian rivers to gain the best river health outcomes (Environment Victoria, 2009). The Buchan River is subject to those policies set out within the VRHS.

Legislation Some of the Legislation that should be considered in the development of any water supply solution includes: x Water Act (1989) x Flora and Fauna Guarantee Act (1988) x Environment Protection Act (1970) x Planning and Environment Act (1987) x Environment Effects Act (1978) x National Parks Act (1975) x Fisheries Act (1995) x Wildlife Act (1975) x Catchment and Land Protection Act (1994) x Environment Protection and Biodiversity Conservation Act (1999).

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4.0 Water Demand This Chapter of the report discusses the estimated current water demands in Buchan and outlines the likely future demand based on predicted population trends. Best practice water supply planning is to use long term average demands for determining existing per capita water demand. Buchan has not been subject to water restrictions since 2003 therefore water use data should provide a good representation of unrestricted demand.

4.1 Current Demand 4.1.1 Previous Demand Estimates The 2006 DRP presented detailed demand forecasts based on historical average annual diversion rates using demand data from 2002 to 2005. The demands outlined in the DRP are shown in Table 2. For the purpose of this report ‘restrictable demand’ is defined as the component of demand which can be eliminated without impacting on ones quality of life (i.e. outdoor demand) while ‘unrestrictable demand’ is largely the component of demand which is necessary for everyday life (i.e. washing, food preparation etc).

Table 2: Monthly Water Demand (based upon the DRP - SKM, 2006) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Total Monthly Demand 3.2 1.6 1.0 1.0 1.6 2.2 3.2 2.6 3.3 2.7 3.1 2.0 27.5 (ML) % of Annual 11.6 5.7 3.8 3.8 6.0 8.0 11.5 9.5 11.8 9.7 11.3 7.4 100.0 Demand Unrestrictable 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 12.4 Demand (ML) 1 Restrictable 2.1 0.5 0.0 0.0 0.6 1.2 2.1 1.6 2.2 1.6 2.1 1.0 15.1 Demand (ML)1 1 Figures have been rounded so may not add up to monthly demand totals

From Table 2 the long term average annual demand has been estimated as 27.5 ML with an unrestrictable demand of 12.4 ML/annum.

4.1.2 Seasonal Pattern of Demand The 2007 WSDS outlined the need to monitor monthly demands at Buchan to gain an improved understanding of seasonal patterns of demand as previous data was showing peaks in both summer and winter. The average monthly outflow from the water treatment plant between February 2007 and January 2010 is shown in Figure 4.

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Figure 4: Seasonal Demand at Buchan (All Available Data – Feb 2007 to January 2010)

The data shown in Figure 4 includes a number of outliers, which could be due to meter resets, extended reading intervals and errors in data recording. These outliers were removed to produce a revised seasonal demand pattern, which is shown in Figure 5.

Figure 5: Seasonal Demand at Buchan (Outliers Removed)

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It can be seen from Figure 5 that the peak month occurs in January and there is no longer a seasonal peak over the winter period (as was the case in the previous WSDS). This seasonal pattern is more likely to represent the actual pattern of demand in Buchan, with peaks over the Christmas and Easter holidays when tourism numbers are significantly higher and reduced demand during the winter months. As a result profile in Figure 5 will be adopted in the development of this WSDS.

4.1.3 Bulk water meter data and historical diversions To assist with establishing an appropriate demand volume for Buchan, available bulk meter data was extracted from EGW’s SCADA system. The volume of bulk water diverted and treated for the last three years is shown in Table 3.

Table 3: Available Bulk Water Meter Data Meter Readings (ML) 06-07 07-08 08-09 WTP Outflow Meter 26.6 20.3 26.5 WTP Raw Water Meter N/A1 N/A1 28.2 1 No readings provided as issues with the meter for a significant period of time during 2007 Review of bulk water meter data (Table 3) indicates that there was a loss of 1.7 ML between the WTP raw water meter and WTP outflow meter during 2008/09. The historical diversion records for the Buchan River dating back to 2001 can be seen in Figure 6. It should be noted that diversion figures between 2001/02 and 2005/06 are only estimates that have been based on Figure 7-4 of the previous WSDS (SKM, 2007).

Increase in diversions due to 2003 bushfire event

Figure 6: Historical Diversions from the Buchan River at Buchan

From Figure 6 it can be seen that the historical diversions at Buchan have ranged between 20 and 27 ML/annum (with the exception of the two years between 2002/03 and 2003/04). During 2002/03 the high diversions can be attributed to bushfires as additional water was used for fire fighting and fire prevention. The reason for the higher than average diversions during 2003/04 is unknown. Based on the information presented in Figure 6, the average annual diversion at Buchan is 26.6 ML/annum; this could be reduced to 25.7 ML/annum if the 2002/03 year were to be excluded.

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4.1.4 Customer Billing Data EGW has provided customer billing data for the Buchan water supply system to assist with determining residential per capita water use. A summary of data provided by EGW is shown in Table 4.

Table 4: Consumption and Connection Data (EGW, 2010)

06/07 FY 07/08FY 08/09FY Residential Connections 80 83 83 Non Residential Connections 31 29 31 Total Connections 111 112 114 Residential Demand (ML) 13.2 9.0 11.3 Non Residential Demand (ML) 10.7 8.9 9.7 Total Demand (ML) 24.0 17.9 21.0 Residential Water Use (L/capita/day) 196.7 129.5 162.2 1 Calculating assuming an average residential occupancy of 2.3 persons per home

It can be seen from the data provided in Table 4 the average annual water consumption is approximately 21 ML. This is less than the average volume of water diverted (as calculated from bulk water meter readings) due to losses within the system and unaccounted and unmetered water (i.e. that used for flushing mains).

4.1.5 Commercial and Industrial Water Use Review of the data provided in Table 4 shows that on average 47% of water is used for commercial or industrial purposes while 53% is used for residential purposes. Based on the previous WSDS (SKM, 2007) it could be concluded that there has been a significant increase in water demand in the commercial and industrial sector and a decrease in the residential sector (previously 29% and 71% respectively). The reason for this shift in demand is currently unknown. Two significant water users have been identified for the town of Buchan. These users have an annual demand of over 1 ML and together have a water demand that accounts for almost 20% of the total annual demand for Buchan. The high water users are listed in Table 5.

Table 5: High Water Users in Buchan Customer 2008/09 Water Percentage of Total Use (ML) Annual Demand Customer 1 4.37 15.89% Customer 2 1.15 4.18%

4.1.6 Unaccounted Water Unaccounted water represents the difference between bulk water sourced from the Buchan River and overall water consumption plus any accounted water not billed by EGW. It includes things such as water lost though leakage, pipe breaks, process water and any water not calculated. Unaccounted water for the last three years as determined by EGW is shown in Table 6.

Table 6: Unaccounted Water (EGW, 2009)

06/07 FY 07/08FY 08/09FY Volume Unaccounted (ML) 1.2 3.8 3.7 Percentage of Total Volume Diverted (%)1 5% 19% 14% 1 Calculated based on WTP outflow meter readings as raw water meter was faulty for a significant period during 2007

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It can be seen from Table 6 that the average volume of unaccounted water in Buchan is around 13% of total water diverted. These losses are slightly higher than those across EGW’s entire area of service, which was reported as 8.5% in their 2008/09 Annual Report. The target set in EGW’s Water Plan is to reduce unaccounted water to 10%.

4.1.7 Summary of Current Demand SKM (2007) reported the long term average annual demand at Buchan as 27.5 ML/annum. This was based upon six years of historical diversion data between 1996 and 2005 and included 2003 where a significant amount of water was used for fire suppression. When incorporating the last three years of data the average annual diversion can be estimated at 26.6 ML. It is therefore reasonable to continue planning for an annual demand of 27.5 ML with seasonal demand patterns as outlined in Figure 5.

4.2 Forecast Water Demand

4.2.1 Previous Population Projections In the previous WSDS prepared by SKM (2007), both available census data and Victoria in Future population projections were used for estimating future population. The WSDS assumed a 67% decline in population between 2005 and 2055. This magnitude of this decline seems unreasonable given that this would see the population fall from 117 to around 60 in the next 50 years.

4.2.2 Recent Census Data The 2007 WSDS identified the need to review 2006 Census data (which was unavailable at the time) to confirm population trends and if the predicted decline in population was reasonable. The 2006 Census data has now been released and is presented in Table 7 in comparison to the 2001 and 1996 Census data results.

Table 7: Census Population Data 1996 Census1 2001 Census1 2006 Census Population 134 142 326 (117) Total Dwellings N/A 73 216 1 Based on data presented by EGSC

Based on the data presented in Table 7 it could be concluded that the population in Buchan has seen rapid growth over the last 5 years, preceded by a period of significantly slower growth. Discussions were held with East Gippsland Shire Council (EGSC) about the variation in population between census years. Council advised the collection district during 2006 included both the township of Buchan and the country area to the north while during 2001 the collection district only covered the township area. Council has advised that the population in 2006 was actually 117 giving a decline in population of around 1.3% per annum between 1996 and 2006. An ongoing decline of 1.3% per annum appears to be unreasonable given that this would see the population fall to around 60 people by 2060.

4.2.3 Victoria in Future Data The Victoria in Future (VIF) population projections for 2008 suggest an overall increase in population throughout the East Gippsland Region. As Buchan is not a major urban centre, the expected population increase is best predicted using the statistical balance (the balance of all those areas outside of major urban centres). The 2008 VIF data suggests a 12.4% increase in population for the statistical balance over a period of 20 years (between 2006 and 2026); this is equivalent to a growth rate of approximately 0.6% per annum. This is much higher than the figures reported in the previous release of VIF (2006), which suggested a decrease of between -1.5% to -2.5% (SKM, 2007).

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The wider projections for regional Victoria show a predicted increase of 1.18% per annum between 2006 and 2026 and 0.78% per annum between 2026 and 2056. These predictions are much higher than those made for the balance of the statistical area (0.6% per annum).

4.2.4 Summary of Population Projections Census data for the ten years between 1996 and 2006 showed a decline in population of around 1.3% per annum. It is considered unreasonable for this rate of decline to continue for another 50 years as this would see the population in Buchan fall to around 60 people. This has been confirmed by EGSC. VIF data is presented for Victoria, major urban centres and a statistical balance. The statistical balance is likely to be most appropriate for estimating future population in Buchan. It is proposed to adopt a growth rate of 0.6% per annum between 2006 and 2026, and a reduced rate of 0.5% per annum between 2026 and 2060 based on VIF data. This results in an overall population increase of approximately 100 people. This is considered to provide a conservative approach towards modelling the water supply system (in terms of growth).

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5.0 Demand Management and Reduction

5.1 Measures to Achieve Demand Reduction Targets The 2007 WSDS detailed both current (at 2007) and future demand reduction initiatives for EGW’s service area. There have been no significant changes since then and as such the majority of this text has remained the same. Sections 5.1.1 and 5.1.2 of this report are direct excerpts from the 2007 WSDS (SKM) with updates provided in italics.

5.1.1 Current Demand Reduction Initiatives (SKM, 2007) East Gippsland Water is currently undertaking measures which are expected to result in per capita demand reduction over time. EGW is part of the savewater!TM alliance through the Victorian Water Industry Association, which represents all of Victoria’s water corporations. Details of the savewater! TM initiative can be found at http://www.savewater.com.au. The site provides information on water conservation, runs competitions to win water conserving products and provides access to suppliers of water conserving products. For estimating the effect of demand reduction initiatives, East Gippsland Water relies upon the detailed demand information derived from Melbourne’s end-use model, which models property scale demand by considering the in- house and external water use of each property (WaterSmart, 2006a). It is acknowledged that there are some differences between consumer behaviour in Melbourne and East Gippsland, however given the high degree of uncertainty surrounding demand reduction forecasts, this adoption of technical information from Melbourne with justifiable adjustments is considered appropriate. In recent years, water conservation efforts by the water utilities and the Victorian Government have targeted all major aspects of residential water use with an emphasis on education and behaviour change. A rebate scheme for water conservation products has been operating since January 2003. For example, AAA shower roses attract a $10 rebate on the purchase price, whilst rainwater tanks with a connection to the toilet for flushing attract a $300 rebate. The most noteworthy regulatory changes affecting residential indoor water use have been: x The introduction of a mandatory water efficiency labelling for appliances (commencing 2006) under the national Water Efficiency Labelling and Standards Scheme (WELS); x The introduction of rising block tariffs, which result in higher charges for high water users; and x The Five Star Home standards which require all new homes in Victoria to have water efficient showerheads, tapware, a pressure reducing valve where mains pressure is over 50 m, and either a solar hot water heater or a rainwater tank connected to the toilet (or equivalent saving through a dual pipe system).

Outdoor water use has been targeted through the introduction of permanent water saving measures, which include the requirement for a trigger nozzle on hoses, restricted times for garden watering, no hosing of paved areas and notification to be given to East Gippsland Water when filling a new pool. These State wide measures are expected to result in a 2% reduction in total demand (TWGWSA, 2005). A per capita demand reduction of 22% has been achieved in Melbourne over the last decade, however some of this demand reduction is due to recent water restrictions and hence it is unclear whether all of this demand reduction will be maintained when restrictions are lifted (Watersmart, 2006b). This reduction includes water savings by industry, government and households. WaterSmart attributes this to water conservation programs, water pricing reform, water audits with major industrial water users, the five star building standard, permanent water saving measures, water saving garden centres, savewater.com alliance, leak control programs and the national water efficiency labelling scheme. Of these activities, East Gippsland Water has only just introduced permanent water saving measures, well after they were introduced in Melbourne, which are expected to result in a 2% reduction in demand (TWGWSA, 2005). This is effective from 2005/06 onwards. EGW also has an active leakage detection program which has completed works in Dinner Plain, Orbost, Cann River, Metung, Paynesville & Eagle Point. These are areas where East Gippsland Water believes that high rates of leakage may occur.

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It could be argued that household disposable income, water corporation revenue and access to information are lower in regional areas than in Melbourne, so the water savings due to other activities could be expected to lag those achieved in Melbourne. Quantifying this lag is difficult, hence it has been conservatively assumed that existing demand reduction measures will merely serve to maintain existing per capita demand, similar to what has been assumed in Melbourne, apart from the initial 2% reduction in demand due to the introduction of permanent water saving measures. This assumption has been carried forward into this updated WSDS for Buchan. Estimating per capita demands in East Gippsland is problematic because of the difficulty in accurately assessing the population being serviced. The estimate of population from census information is only collected in winter and therefore significantly underestimates peak summer and Easter populations, which swell due to an influx of tourists to the region. The above paragraph is written in the context of all of EGW’s supply systems which include coastal towns such as Lakes Entrance. The average daily per capita demand has been estimated based on customer billing data, recent census data and Victoria in Future population projections. From this information the average daily water use is 163L/day per person (based on available data). Given that Buchan does have a tourist population during Christmas and Easter holidays, it is possible that the average daily demand (per person) is overestimated. Estimating a change in per capita demand is equally problematic without knowledge of changes in seasonally weighted populations. This is because a change in winter population does not necessarily translate directly into a linear change in summer population, which is affected by the state economy (influencing disposable income and therefore travel decisions), weather conditions and accommodation capacity.

5.1.2 Future Demand Reduction Initiatives (SKM, 2007) East Gippsland Water will actively pursue demand reduction in each supply system. East Gippsland Water has set itself a demand reduction target in line with State Government targets set for other water corporations across Victoria of: x A 25% reduction in per capita demand by the year 2015 relative to 1990s average demand; and x A 30% reduction in per capita demand by the year 2020 relative to 1990s average demand.

Assuming that the 22% reduction in per capita demand has already been achieved in East Gippsland, East Gippsland Water would require a 3% reduction in per capita demand from its customers by the year 2015 and an 8% reduction in per capita demand by the year 2020 in order to reach this target. This includes the 2% reduction in demand due to the recent introduction of permanent water saving measures that is not likely to have been realised relative to the 2005/06 demand data used in this strategy. A range of actions by East Gippsland Water and the State Government will be required to meet these targets. It is anticipated that the majority of these actions would be driven by the State Government and Melbourne’s urban water utilities. Specific actions by East Gippsland Water include the following: x East Gippsland Water will continue to work with its major customers to reduce the water use of those major customers. x East Gippsland Water will continue its leak reduction program. x East Gippsland Water will continue to keep abreast of technological developments in water saving measures currently being investigated by Melbourne’s urban water utilities through East Gippsland Water’s membership of the Victorian Water Industry Association.

Specific actions by other organisations that will contribute to East Gippsland Water’s customers achieving the demand reduction target are as follows, as outlined in the Central Region Sustainable Water Strategy: x The State Government will extend its existing water savings behavioural change program until 2015. – This program is still running x The State Government will by 2006/07 introduce on-the-spot fines for breaching water restrictions or the permanent water saving measures – This has been adopted

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x The State Government will reform the water component of the 5-star building standard to make it performance based. x The State Government will by 2010 seek the adoption of standards under the national Water Efficiency Labelling Scheme for water appliances to set mandatory minimum or higher than existing standards for showerheads, washing machines, toilets and evaporative coolers x The State Government will consider the rollout of smart water meters showing real time water use after completion of a trial in south east Melbourne by December 2007 – Trials completed and smart water meters were provided to Melbourne’s top 200 industrial water users. During 2007 the Victorian Government advised that Smart Water meters will be rolled out to all customers using 10 million litres or more of water per year. x The Water Smart Homes and Gardens Rebates scheme, currently funded by the Victorian Water Trust, will be extended for a further four years until June 2011. This scheme makes rebates available for water tanks, dual flush toilets, greywater systems and other water saving appliances and devices – Scheme is still active x The State Government will develop a web-based ready reckoner to assist home owners in choosing different water saving options for their home by 2007 – This action has been completed x The State Government will continue until 2009 the Sustainable Water Efficiency Program for schools. This involves an audit of indoor water use and a retrofit of fittings and appliances – This program is still running

The extent to which demand reduction targets are achievable in any given year will be influenced by the age profile of assets, particularly in small supply systems, of which East Gippsland Water operates several. As assets such as pipelines approach the end of their useful life, they will leak or burst, increasing water losses. Measuring the effectiveness of these actions against East Gippsland Water’s target will be based on measuring the change in the per capita demand from the current 335 litres per capita per day to 325 litres per capita per day by 2015 and 310 litres per capita per day by 2020. These targets are based on an assumed seasonally weighted population of double the winter population. Meeting these targets also assumes that the seasonally weighted population increases in proportion to the increase in winter population for the period over which the targets have been set.

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6.0 Water Supply

6.1 Future Reliability of Surface Water 6.1.1 Impact of Climate Change The greatest concern for Buchan’s water supply system relating to climate change is a significant reduction in the volume of surface water available for extraction from the Buchan River. A report titled “Future Runoff Projections (~2030) for South East Australia” by the South Eastern Australian Climate Initiative (SEACI, 2008) was used as the basis for obtaining streamflow reduction figures. The methodology used in this paper is similar to the paper “Rainfall-runoff modelling across the Murray-Darling Basin” (CSIRO, 2008), which was used to source stream flow reduction figures for the Omeo WSDS (2010). The key difference between these reports is that the SEACI report uses only a medium emissions scenario to formulate runoff scenarios, while the CSIRO report also considered a high and low scenario. The SEACI report has been adopted for input into the WSDS as it specifically covers the area of Buchan while the CSIRO report does not. The percentage change in modelled mean annual runoff for Buchan (~2030 relative to 1990) based on SEACI modelling is projected to be -6.3% for the median scenario and -11.3% for the dry scenario. The dry scenario has been selected as the most prudent scenario (i.e. a -11.3% change in mean annual runoff) upon which to plan future water supply given the Gippsland Region Sustainable Water Strategy: Discussion Paper (2009) notes that the low inflows experienced since 1997 may represent a permanent step change in reservoir inflows. More comprehensive information regarding the potential impacts of climate change on water supply is scheduled to become available in the first half of 2010, including: x Finalisation of the Gippsland Region Sustainable Water Strategy – this is expected to provide guidance regarding considering potential impacts of future climate change for the purpose of water supply planning x SEACI modelling for the high emissions scenario published: current climate projections are only available for the medium emissions scenario for the SEACI region, which includes the majority of EGW’s supply area. Based on recent climate change science (e.g. Rahmstorf 2007), we are currently tracking at or above worst case scenarios for emissions and temperature, and it is therefore prudent to plan based on a high emissions scenario. For the purposes of this report the published results from SEACI report have been adopted, however EGW should consider reviewing these assumptions in late 2010 when the additional data is released.

6.1.2 Step Change It is possible that the low inflows that have been experienced since 1997 represent a permanent step change. SEACI will be conducting research over the next three years to investigate the reasons for the recent dry conditions and determine the suitability of the various global climate models for south eastern Australia. It may take decades before it is understood if the inflows of the past 12 years are part of the normal cycle of climate variability or if a permanent step change has been experienced. As such, it is important to ensure that water supply planning takes this possibility into consideration. Streamflow gauging on the Buchan River has been relatively continuous since its commencement in 1948. It is difficult to quantify how step climate change has impacted flows in the Buchan River predominantly due to the increases in streamflow that would have resulted from the 2003 bushfires that burnt around 77% of the Buchan catchment. When comparing the last 12 years of streamflow data to the historical record it can be seen that there has been a reduction of around 52% in annual streamflow. This reduction in streamflow is likely to be underestimated due to the countering impact of the increases in run-off due to the 2003 bushfires. The estimated step change of 52% is significantly higher than the dry climate change scenario, therefore will be used when modelling the high impacts associated with climate change.

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6.2 Impact of Bushfires Bushfires in forested catchments have the potential to significantly impact runoff and therefore streamflows over time. The Buchan River catchment area upstream of the town off-take is largely native forest with the predominant tree species being mixed eucalypt.

6.2.1 Previous Bushfires During the summer of 1982/83 significant wildfires burnt around 3400 hectares of forested land within the Buchan water supply catchment. It is now almost 27 years after the fire and the catchment may have already experienced a decrease in runoff due to the impact of that bushfire. SKM (2009) reported that the 2003 bushfires burnt approximately 77% of their study catchment which is equivalent to 77% of the catchment upstream of Buchan. The Buchan water supply catchment was not impacted by the 2006/07 fires. Runoff after bushfires initially increases in the first few years until vegetation starts to re-grow, whereupon runoff starts to decrease. This impact is demonstrated by the stream flow response curve presented in Figure 7. The curve details predicted changes in streamflow resulting from the 2003 bushfires for the Buchan River catchment within which Buchan resides.

Figure 7: Estimated reduction in streamflow in the Buchan River due to the 2003 bushfires (SKM, 2009)

The curve in Figure 7 suggests the catchment is yet to experience the projected decrease in streamflow and that the maximum reduction in streamflow will not occur until around 2025. Beyond this time period, streamflows will gradually return to pre-bushfire levels as the new forest matures. Streamflow reductions for key modelling time-steps are interpolated from Figure 7 as follows: x The current impact of the 2003 bushfires in terms of changes to streamflow is negligible (i.e. 0% change) x At 2025 it is expected that the reduction in streamflow associated with the bushfires will be around 35% x At 2060 the expected reduction in streamflow associated with the bushfires will be around 20%.

Discussions with DSE and review of SKM’s bushfire report (2009) have provided an appreciation for the complexity of the interactions between climate change and the impacts associated with bushfires. SKM (2009) stated that:

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“… the impact of climate change on water resource yield is likely to interact with the expected response following a bushfire such that the two processes may not be independently identifiable. It is not clear how the interaction of the bushfire and climate change impacts on climate change will play out into the future”.

DSE has advised that the percentage reductions in streamflow resulting from forest regrowth after a bushfire would be lessened in a drier climate. To account for this, a sensitivity analysis on the magnitude of bushfire impacts was undertaken.

6.2.2 Proposed Fuel Reduction DSE is proposing to undertake fuel reduction burns in the lower yielding portion of the catchment over the next 3 years. These fuel reduction burns will impact on 3.7% of the Buchan water supply catchment. EGW has raised concerns about this burning regime stating that: “… it has been estimated that we should expect an 85% reduction in streamflow in future summers. Such an outcome has potential to have serious consequences for the township of Buchan”.

EGW has requested that fuel reduction burns within the Buchan River catchment be approached in a similar manner to the Mitchell River catchment (i.e. 5% of the catchment per year, focusing in the earlier stages in the higher yielding parts of the catchment). This request is currently pending, the outcomes remain unavailable to date. Discussions with DSE have confirmed that runoff impacts from fuel reduction burning are expected to be minor and do not need to be considered in the WSDS.

6.3 Forestry Areas within the Buchan River catchment are logged on a rotation basis. Similar to the impacts of bushfires, logging reduces streamflows in the long term as the forests re-establish. From review of available information it seems that logging has predominantly occurred on the western side of the catchment with a total area of between 10 and 15% of the overall catchment logged since 1970. The previous WSDS concluded that the impact of this logging on the off-take would be relatively small, provided the logging remains dispersed across the catchment (SKM, 2007). To ensure reliability of supply it is recommended that EGW continue to monitor the impacts of logging and if long term supply begins to diminish, seek a reduction in the area to be logged within the water supply catchment.

6.4 Future Streamflow Projections The effect of climate change and bushfire impacts on future streamflow is demonstrated in Figure 8. It can be seen that a continuation of low flows or step change has the greatest potential to impact upon streamflow availability in the Buchan River. The step change scenario assumes that the low inflows over the last 12 years are a permanent change. Bushfires will also have a significant impact on streamflow availability in the coming years (2020 – 2024) with a lessening impact as the forest begins to recover.

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Figure 8: Future Streamflow Projections

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7.0 Reliability of Supply 7.1.1 Method Overview The method adopted for the REALM modelling can be summarised as: x Review previous SKM model and identify any issues; x Collate streamflow data and update where possible; x Undertake preliminary modelling (current situation); x Review restriction triggers; and x Undertake further modelling and produce output graphs.

7.1.2 Modelling Assumptions Streamflow Data x Data from gauging station 222206A was used as this was considered to be the most appropriate location for measuring streamflow x Private diversions have not been considered in the model as a total ban would be placed on all upstream users when the flow is reduced to less than 4 ML/day, it is therefore reasonable to assume that EGW will not be impacted by upstream diversions as the maximum rate that EGW can extract water at is 1.05 ML/day.

Demand Data x The demand patterns within the previous model have been revised based on the latest available data (refer to Figure 5 for the revised demand profile). The previous demand of 27.5 ML/annum has been adopted x For the future (2060) scenario an increased demand figure was used. The rate of growth was 0.6% per annum between 2006 and 2026 and 0.5% per annum between 2026 and 2060. This is considered to provide a conservative approach. x It was assumed that population and demand are linearly linked. The base year for determining the population growth was 2010. x The reductions in demand due to the onset of restrictions is as follows (based on EGW water restriction by- laws): Stage of Restriction Annual Reduction of Total Demand (%) One 2.5 Two 8 Three 12 Four 17.5

Climate Change x It is assumed that the impacts of climate change will be realised by 2030, after this time the model infers that there will be no further reduction in streamflow due to climate change. This assumption will need to be reviewed upon release of updated climate change information. x The reduction in streamflow will occur in a linear fashion, reducing by a fixed amount each year between 1990 and 2030 x The increase in demand associated with climate change (2% under SEACI projections or 8.5% under the step climate change scenario) will be offset by further developments in water efficiency driven by EGW’s target of 8% reduction in per capita demand to be achieved by 2020 (SKM, 2007)

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7.2 Current Reliability of Supply The existing water supply system was modelled to assess its reliability with regards to EGW’s LOS objectives. Two scenarios were considered for modelling the current situation; these are detailed further as follows: x Scenario 1 (Figure 9) assumes dry climate change based on SEACI predictions (i.e. 5.7% reduction in streamflow at 2010 based on an overall reduction of 11.3% by ~2030) x Scenario 2 (Figure 10) assumes a step change in streamflow due to climate change and is based on streamflow records for the past 12 years (i.e. 52% reduction in average annual streamflow).

Bushfire impacts were considered to be minor for both scenarios at this point in time as 2010 is very close to the transition point of the initial streamflow increase and future streamflow decrease. The current restriction triggers as stated within the DRP (SKM, 2006) were adopted for modelling the current situation; these triggers are shown as follows: x Voluntary – Streamflow <= 1.5 ML/day x Stage 2 – Streamflow <= 0.7 ML/day x Stage 4 – Streamflow <= 0.3 ML/day

The current situation model (2010) for Scenario 1 is shown in Figure 9 and Scenario 2 is shown in Figure 10.

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Stage 4

Stage 2

Voluntary

Figure 9: Current Reliability of Supply (Assuming dry climate change predictions by SEACI)

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Stage 4

Stage 2

Voluntary

Figure 10: Current Reliability of Supply (Assuming a step change in climate)

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Both Figure 9 and Figure 10 show that under the current situation, regardless as to the climate scenario adopted, EGW is meeting their LOS objectives at Buchan. The current LOS for both scenarios is summarised in Table 8.

Table 8: Current Levels of Service Restriction Level Restriction Frequency Restriction Frequency Scenario 1 Scenario 2 Voluntary N/A 1 in 62 years Stage 2 1 in 62 years N/A Stage 4 N/A 1 in 62 years

Under both scenarios, the clear water storage is consistently full. Based on modelling of the current situation it can be concluded that Buchan’s water supply system is extremely reliable. Daily flow data recorded at Buchan (Gauge 222206A) shows that there has only been one day in the last 62 years where EGW would have been unable to extract their full entitlement of 1.05 ML.

7.3 Future Reliability of Supply 7.3.1 Year 2030 To assess EGW’s ability to meet LOS objectives in the future, additional REALM modelling was undertaken. The time at which water supply security at Buchan will be most critical is at 2030 when streamflow reductions due to bushfires will be at their greatest. Discussions with DSE have indicated that the percentage reductions in streamflow resulting from forest regrowth after a bushfire would be lessened in a drier climate (refer Section 6.2 for further discussion) although the degree to which the reductions will occur is unknown. To assess the water supply system’s ability to cope under the most dire climate change, bushfire and growth scenarios, the modelling inputs detailed in Table 9 were used.

Table 9: Modelling Scenario (2030) Modelling Parameter Adopted Value Climate Change Streamflow Reduction (2030) -52% Bushfire Streamflow Reduction (2030)1 -35% (Full reduction at 2030) Growth (per annum) 0.6% (2006 to 2026) and 0.5% (2027 to 2030) 1 Climate change adjusted streamflows have been the basis for bushfire reductions

The results can be seen in Figure 11.

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Stage 4

Stage 2

Voluntary

Figure 11: Future Reliability of Supply (2030)

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It can be seen from Figure 11 that under the scenario outlined in Table 9, LOS objectives will continue to be met in the year 2030. The model shows that voluntary restrictions would be triggered once in every 12 years, Stage 2 restrictions would be triggered once in every 20 years and Stage 4 restrictions would be triggered once in every 31 years. Based on advice from DSE regarding the lessened impact of bushfires under a drier climate a sensitivity analysis was undertaken using varied bushfire impacts, all other parameters (step climate change and growth) remained constant. The results are show in Table 10.

Table 10: Bushfire Sensitivity Analysis Scenario Level of Service Objectives Voluntary Stage 1 Stage 2 High Bushfire Impact 1 in 12 years 1 in 20 years 1 in 31 years (100% of bushfire impact) Moderate Bushfire Impact 1 in 20 years 1 in 31 years 1 in 62 years (75% of bushfire impact) Low Bushfire Impact 1 in 31 years 1 in 62 years 1 in 62 years (50% of bushfire impact)

It can be seen from Figure 11 and Table 10 that the REALM modelling shows that EGW will continue to meet their LOS objectives under the most dire of climate change, bushfire and growth scenarios. LOS objectives will be improved if the bushfire impacts are lessened due to a drier climate as predicted by DSE. Under all scenarios, the clear water storage is consistently full. The diversion weir on the Buchan River is estimated to have around 7 days of supply with a further 13 days provided by the clear water storage. Together these storages could supply the town of Buchan for 17 days in the event of the river running dry. Given that a new larger storage is to be constructed at Buchan, the volume of storage and days of supply will further increase.

7.3.2 Year 2060 One further modelling scenario was undertaken to review expected LOS objectives at the end of planning period (2060). The inputs used for this model are shown in Table 11.

Table 11: Modelling Scenario (2060) Modelling Parameter Adopted Value Climate Change Streamflow Reduction (2060) -52% Bushfire Streamflow Reduction (2060) -15% (Reduced from 20%) Growth (per annum) 0.6% (2006 to 2026) and 0.5% (2027 to 2060)

The results can be seen in Figure 12.

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Stage 4

Stage 2

Voluntary

Figure 12: Future Reliability of Supply (2060)

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It can be seen from Figure 12 that under the scenario outlined in Table 11, LOS objectives will continue to be met in the year 2060. The model shows that voluntary restrictions would be triggered once in every 20 years, Stage 2 restriction would be triggered once in every 62 years and Stage 4 restrictions would also be triggered once in every 62 years. It should be noted that one event in the 62 year model simulation resulted in all three restriction triggers being reached (as shown in Figure 12).

7.3.3 Summary REALM modelling of the Buchan water supply system has shown that the Buchan River is very reliable in providing the required volume of water to the town. Under reduced streamflow conditions (due to climate change and bushfires) supply to the town can be managed with currently available infrastructure. The greatest risk to Buchan’s water supply system is a decline in water quality (from impacts such as bushfire). In the event that water quality within the Buchan River deteriorates to a point where it is rendered unsuitable, alternative water supply arrangements will be required.

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8.0 Management of Water Supply The follow sections of this report outline a number of potential options for securing water supply in times of extreme drought, bushfire events or other emergencies.

8.1 Water Loss Reduction Data provided in Table 6 indicates that during the last financial year approximately 3.7 ML (or 14% of total water diverted) was lost within the system. While reducing the level of leakage will not significantly improve water security, it will provide more water for the environment and reduce system operating costs. EGW should therefore investigate the cause for the high losses and implement any remedial measures deemed to be cost effective.

8.2 Water Carting Water carting should only be considered as an emergency supply in the event that Buchan’s water storage approaches critically low levels or when quality of supply from the Buchan River is compromised (due to bushfires). Water could be carted from one of EGW’s other water supply zones such as Orbost, Nowa Nowa or Bruthen. Nowa Nowa would be closest location to cart from at around 34 km. It is estimated that the cost to cart water from Nowa Nowa would be in the range of $12,000 per ML with approximately 2 trips per day required (during peak demand, assuming Stage 4 restrictions). While the unit price of supply is extremely high, modelling indicates that on average water carting should be required no more than 1 in 62 years and therefore is financially viable compared to investing in large infrastructure that may be used infrequently or not at all.

8.3 Buchan Caves EGW has previously trialled water supply from a natural spring at Dukes Cave within the Buchan Caves Reserve. This trial found that the water was excessively hard with an average CaCO3 concentration of more than 600 mg/L (during 2007). This caused issues with customer’s appliances (hot water systems etc). The Australian Drinking Water Guidelines (ADWG, 2004) state that CaCO3 levels above 500 mg/L can cause severe scaling, as was experienced at Buchan. It is understood that infrastructure is already in place to transfer water from Dukes Cave to the storages although discussions with EGW indicate that this is unlikely to be used again in the future due to the quality issues. Water carting from other locations throughout the reserve may be an alternative in times of emergency although water would need to be tested to confirm its appropriateness for use and access would need to be co-ordinated with Parks Victoria, who are the managing authority of the reserve. Additional pre-treatment is likely to be required to use water from the Buchan Caves Reserve.

8.4 Groundwater Groundwater does not currently form part of Buchan’s water supply system. Groundwater could be used as an emergency supply in the future although this would require construction of a bore. SKM (2006) stated that: “Groundwater could be used as an emergency source of water in all of the towns in this DRP. Lithology is characterised by fractured and weathered indurated sediments, metasediments and intrusives in the vicinity of Buchan (Dept. of Minerals and Energy, 1981).” “Groundwater salinity in the region of Gippsland covered by this DRP (which includes Buchan) is generally less than 1000 mg/l, which is suitable for drinking. Yields are generally below 10 L/sec.” “The lead time to drill a new groundwater bore is likely to be around one to three months, dependent on the complexity of drilling and design construction. Tasks involve selecting a new site, obtaining internal expenditure approval, obtaining a bore construction licence, obtaining a driller, acquiring bore materials, drilling the bore, pump testing of the bore and water quality testing of the bore”.

Given the modelled low frequency of alternative supply being required and the capital costs associated with investigation and construction of a new bore, it is recommended that EGW adopt carting as their first preference

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for alternative water supply. If water security issues arise in the future, EGW should reconsider the need to drill a drought relief bore.

8.5 Recommendations for Managing Supply A number of options have been identified to improve the security of Buchan’s water supply system. It is recommended that EGW: x Continue to monitor and strive to reduce losses within the water supply system; x In times of emergency, cart water from Nowa Nowa, Orbost, Bruthen or as an absolute last resort, the Buchan Caves Reserve. x Continue to implement demand reduction strategies to assist in achieving EGW”s demand reduction targets (8% reduction in per capita demand by 2020).

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9.0 Stakeholder Consultation Stakeholder consultation was undertaken as part of the 2007 WSDS. As this WSDS forms an interim document, stakeholder consultation has not been undertaken.

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10.0 Conclusions and Recommendations

10.1 Conclusions Recent studies and observations have shown that the impacts of climate change and bushfires on streamflow availability in the Buchan water supply catchment will be significant. To account for this, REALM modelling was undertaken to investigate how the existing water supply system will perform into the long term future. Modelling for all scenarios showed that the Buchan River is very reliable in terms of providing the required level of service to the town. Under both current (2010) and future (2030 and 2060) modelling scenarios, EGW is able to meet their LOS objectives with current infrastructure and restriction triggers. Daily flow data recorded at Buchan (Gauge 222206A) shows that there has only been one day in the last 62 years where EGW has been unable to extract their full entitlement of 1.05 ML. It was concluded EGW will continue to be able to meet their LOS objectives for Buchan over the next 50 years even considering the significant impacts of climate change, past bushfires and growth in water demand. As a result, further supply enhancement will not be required. The greatest risk to Buchan’s water supply system is deterioration in water quality due to impacts such as bushfire. A number of alternative supply options were assessed to ensure continuity of supply during such emergencies. From this assessment the most suitable alternative was determined to be emergency water carting.

10.2 Summary of Recommendations Following this update of the WSDS for Buchan, it is recommended that EGW action the following strategies for the Buchan water supply system. Implementing all of these recommendations will be resource intensive and EGW should prioritise implementation in accordance with the below action plan.

Table 12: Action Plan Action Implementation Update Buchan’s Drought Response Plan. This plan Immediate should document the drought response options outlined in Section 8.0. Continue to monitor and strive to reduce losses within Ongoing the water supply system Continue to implement demand reduction strategies to Ongoing assist in achieving EGW”s demand reduction targets (8% reduction in per capita demand by 2020) Continue to monitor the impacts of logging and if long Ongoing term supply diminishes seek a reduction in the area to be logged within the water supply catchment Undertake a water audit for the high water users Longer term

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11.0 References AECOM, (2010) Omeo Water Supply Demand Strategy

Chiew, F., Vaze, J., Viney, N., Jordan, P., Perraud, J-M., Zang, L., Teng, J., Arancibia, J A., Morden, R., Freebairn, A., Austin, J., Hill, P., Wiesemfeld C., and Murphy, R. (2008) Rainfall-runoff modelling across the Murray-Darling Basin A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project

CSIRO, (2008) Rainfall-runoff modelling across the Murray-Darling Basin

Department of Primary Industries (DPI), 2010 http://www.dpi.vic.gov.au/dpi/vro/egregn.nsf/0d08cd6930912d1e4a2567d2002579cb/96c23880514470 20ca25751a000892b0/$FILE/tambo_boggy_14-29.pdf)

DPI (2010) http://www.nre.vic.gov.au/angling/22-Snowy/Basin%20TEMPLATE%20Waters.htm

DSE, (2005) Guidelines for the Development of a Water Supply Demand Strategy

DSE, (2009) Gippsland Region Sustainable Water Strategy – Discussion Paper

EGW (2009) – 17/04/2009 http://www.egwater.vic.gov.au/NewsandPublications/MediaReleases2010and2009/tabid/142/Default.aspx

Environment Victoria (2009) http://www.envict.org.au/inform.php?menu=7&submenu=220&item=668

Lane, P., Sheridan, G., Noske, P., Costenaro, J., Sherwin, C., Szegedy, G and McKenna, P (2009). Dynamics of sediment and nutrient fluxes from burnt forest catchments. Final Report prepared for Land & Water Australia.

Lane, P., Sherwin, C., Peel, M., Freebairn, A. (2007) Impact of the 2003 Alpine Bushfires on Streamflow - Predicting the long-term impacts of bushfire on water yield. Report for the Murray-Darling Basin Commission and the Department of Sustainability and Environment.

National Health and Medical Research Centre (2004) Australian Drinking Water Guidelines

Rahmstorf et al, (2007) Recent Climate Observations Compared to Projections. Science 316, 1.

South Eastern Australian Climate Initiative, (2008) Future Runoff Projections (~2030) for South East Australia

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SKM, (2009) Combined impact of the 2003 and 2006/07 bushfires on streamflow - Broadscale Assessment

SKM, (2007) East Gippsland Water: Water Supply Demand Strategy

SKM, (2006) East Gippsland Water: Drought Response Plan – Bemm River, Buchan, Cann River, Marlo, Newmerella and Orbost

SRW, (2009) http://www.srw.com.au/Files/Local_management_rules/snowy_local_Management_Rules_Sept09.pdf

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