Cann River Water Supply Demand Strategy

9 September 2010

Cann River Water Supply Demand Strategy AECOM

Cann River Water Supply Demand Strategy

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

9 September 2010

60144336 Task 1.03

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9 September 2010 Cann River Water Supply Demand Strategy AECOM

Quality Information

Document Cann River Water Supply Demand Strategy

Ref 60144336 Task 1.03

Date 9 September 2010

Prepared by L Dragicevich

Reviewed by S Wallner / M Habener

Revision History

Authorised Revision Revision Date Details Name/Position Signature

A 16-Apr-2010 Draft for Client Comment Elisa Hunter Original Signed

B 27-May-2010 Issued for Technical Elisa Hunter Original Signed Committee Review C 16-Jul-2010 Final Issue Andrew Grant Original Signed Associate Director - Water D 09-Sep-2010 Final Issue for Publication Elisa Hunter

9 September 2010 Cann River Water Supply Demand Strategy AECOM

Table of Contents Executive Summary i 1.0 Introduction 1 1.1 Regional Setting 1 1.1.1 Cann River Township 1 1.1.2 Cann River Catchment 2 2.0 Current Water Supply 3 2.1 Description of Water Supply System 3 2.2 Allocation of Water 4 2.2.1 Bulk Water Entitlements 4 2.2.2 Licensed Private Diversions 4 2.2.3 Groundwater Licence 5 2.3 Level of Service Objectives 5 2.4 Historical Water Restrictions 5 3.0 Previous Studies, Legislation and Regulation 6 3.1 Previous Long Term Planning Studies 6 3.1.1 Drought Response Plan for Bemm River, Buchan, Cann River, Marlo, Newmerella and Orbost (SKM, 2006) 6 3.1.2 EGW Water Supply and Demand Strategy (SKM, 2007) 6 3.2 Regulations and Legislation 6 3.2.1 Surface Water Caps 6 3.2.2 Streamflow Management Plans 6 3.2.3 Groundwater Caps 6 3.2.4 Heritage Rivers 7 3.2.5 Other Legislation 7 3.3 State and Regional Strategies 8 3.3.1 Regional River Health Strategy 8 3.3.2 Victorian River Health Strategy 8 4.0 Water Demand 9 4.1 Current Demand 9 4.1.1 Historical Diversions 9 4.1.2 Monthly Water Demand 10 4.1.3 Seasonal Fire Fighting Demand 10 4.1.4 Unaccounted Water 11 4.1.5 High Water Users 12 4.2 Forecast Water Demand 12 4.2.1 Census Data 12 4.2.2 Victoria in the Future Data 12 4.2.3 East Gippsland Shire Council 12 4.2.4 Summary of Demand Projections 12 5.0 Demand Management 13 5.1 Measures to Achieve Demand Reduction Targets 13 5.1.1 Current Demand Reduction Initiatives 13 5.1.2 Future Demand Reduction Initiatives 14 6.0 Water Supply 16 6.1 Risks to Reliability of Supply 16 6.1.1 Impact of Climate Change 16 6.1.2 Step Change 16 6.1.3 Impact of Bushfires 18 6.1.4 Forestry 19 6.1.5 Water quality 19 6.2 Future Reliability of Groundwater 20 7.0 Current and Future Reliability of Supply 21 7.1 Reliability of Supply 21 7.2 Review of Restriction Triggers 21 7.2.1 Existing restriction triggers 21

9 September 2010 Cann River Water Supply Demand Strategy AECOM

7.2.2 Suitability of Existing Trigger Levels 22 7.2.3 Revised Restrictions 22 8.0 Alternative Water Supply Options 23 8.1 Short Term Drought Relief 23 8.1.1 Qualification of Rights on the Cann River 23 8.1.2 Water Trading 23 8.1.3 Raw Water Storage 23 8.1.4 Water Carting from Other Rivers 24 8.1.5 Pump from Existing Bore 24 8.1.6 Pump from New Bore 25 8.1.7 Conversion of the Clear Water Storage to a Raw Water Storage 25 8.1.8 Accessing Groundwater from the Cann River (and Off-take Improvements) 25 8.1.9 Option Comparison 26 8.2 Demand Management 27 8.3 Water Loss Reduction 27 8.4 Proposed Amendment to the Drought Response Plan 27 9.0 Stakeholder Consultation 29 10.0 Conclusions and Recommendations 30 10.1 Conclusions 30 10.2 Summary of Recommendations 30 11.0 References 31 Appendix A Desktop Groundwater Review A

9 September 2010 Cann River Water Supply Demand Strategy AECOM

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 their existing WSDS for the Cann River water supply system. This revised WSDS will replace the strategy set out for Cann River in EGW’s overall WSDS (Section 8). Objectives EGW has set level of service (LOS) objectives for water supply reliability. The objectives state that:  Moderate restrictions (Stages 1 & 2) are not desired more frequently on average than 1 year in 10  More severe restrictions (Stages 3 & 4) are not desired more frequently than 1 year in 15.

These LOS objectives have been used as a basis for assessing the adequacy of Cann River’s current water supply system for meeting current and future water demand. Impacts of Climate Change and Bushfires South Eastern Australian Climate Initiative (SEACI, 2008) predicts a 10.1% reduction in mean annual runoff for the Cann River region by the year 2030. The impact of a continuation of the last 12 years of streamflows was also assessed which indicated that such a step change in climate would yield a 62% decrease in mean annual streamflows. In addition there is significant uncertainty regarding how groundwater supplies will be impacted by climate change. Recent bushfires in the region have not significantly impacted the Cann River catchment. Reliability of Supply Given the absence of recent data or an indicative low flow period by which to derive a meaningful streamflow correlation, it was considered that modelling would be of little value in assessing Cann River’s future supply strategy for this study. In the absence of modelling, the following information was considered when evaluating the likely reliability of Cann River as a future supply source:  Annual streamflows under the high climate change scenario are expected to reduce by 10.1%, while a step change scenario could see a more severe reduction of 62%(reductions are anticipated to be greater during summer)  The river has run dry twice in the last four years including a short duration in January 2010  Fires near Cann River during January 2010 resulted in DSE mobilising a large number of staff into the town. The town supply was used for fire fighting purposes, and this resulted in tripling of demand. Irrigation extractions also increased with the threat of fire  Historical restrictions have only been imposed twice (1998 and 2003)  Current storages provide four weeks of demand under Stage 4 restrictions  Future growth in demand is expected to be moderate in relation to average streamflows  There is currently no formal backup groundwater supply  Groundwater supplies are considered to be currently available but long term sustainable extraction limits are not known and demand for the resource is expected to come under increasing pressure in a drying climate.

Consideration of the above data suggests that there is much uncertainty regarding the ability of Cann River to be a reliable supply source into the future. A review of current water restriction trigger levels and identification of available backup supplies and strategies is therefore required to inform decisions on potential alternative supply and demand management strategies.

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Drought Supply Options A number of alternative water sources were identified to supply Cann River in the event that the river runs dry for a significant period of time. These included accessing groundwater in Cann River and carting surface water from other sources. Given that improvements may be required to the existing river intake well in the near future, it is proposed that EGW investigate modifying the intake arrangement to incorporate access to subsurface flow below the river bed. This could be achieved with the installation of spear point pumps, and EGW should continue to engage with both Southern Rural Water and the East Gippsland Catchment Management Authority to establish both licence requirements and the extent of environmental studies that may be necessary. A desktop assessment confirmed that it is possible that groundwater in Cann River could provide a suitable emergency water supply. To confirm this as viable drought response option, it is recommended that EGW undertake more detailed assessments as described in the action plan below. Carted water from either an existing groundwater bore at the Cann River Caravan Park or from river sources would presently be unloaded into the river intake well in order to be pumped to the treatment plant. The nature of the river bed in the intake well would mean that losses are high, which therefore implies a greater number of tanker loads to deliver the required water. In the interim, or in the event that modifications to the river off-take are infeasible, the following alternatives are available:  Construct a new clear water tank (330kL) and convert the existing clear water basin into a raw water basin  Construct a new raw water tank (30kL) and retain the existing clear water basin.

It would be considerably cheaper to construct 30kL of raw water storage when compared to 330kL of clear water storage. Recommendations In conclusion it is recommended that EGW implement the following action plan: Action Implementation Update the Drought Response Plan for Cann River in accordance with the recommendations Immediate presented in Section 8.4. Engage with SRW and the EGCMA to determine viability of the proposal to modify the river Immediate intake arrangement, including licence requirements and extent of any environmental studies. Determine if groundwater from the existing bore is suitable for potable supply and formalise Immediate access arrangements by undertaking the following actions:  Conduct pump tests and water quality tests on the existing groundwater bore that was previously owned by EGW and was recently handed over to EGSC for fire fighting purposes.  Conduct a hydrogeological assessment to assess bore performance. The assessment would also include research on other groundwater users in the area, so that potential impacts to these users could be evaluated  Pending the outcomes of the above assessment, seek to formalise priority access to the bore during emergency supply situations via an amendment to the existing groundwater extraction licence. Develop communication protocols with DSE for extended periods of fire-fighting activity. Immediate Continue existing leak detection programs to ensure the system operates in an efficient manner. Ongoing Continue to monitor the impacts of logging and if a long term supply shortage is anticipated then Ongoing seek a reduction in the area to be logged within the water supply catchment. Engage with the EGCMA to discuss the implications for raw water quality of Cann River’s supply Immediate from stock watering within the catchment, particularly during periods of low flow. Construct of a new raw water tank (30kL) at the treatment plant to enable carted water to be 2010 unloaded without losses. Seek to reduce current water demand by auditing high water users and identifying possible 2010/11 savings.

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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 in 2007, however is now reviewing the strategies for water supply systems that are experiencing critical shortages resulting from the combined impacts of the ongoing drought, climate change and bushfires. WSDS are otherwise required to be reviewed and updated at least every 5 years. Continuing dry conditions have resulted in a significant drop in streamflow right across Victoria and East Gippsland has not been exempt from these impacts. CSIRO has 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 the Department of Sustainability and Environment (DSE) during preparation of the earlier WSDS may over-estimate long term yields. The previous WSDS for Cann River recommended that EGW:  Reduce uncertainty in current estimate of consumer demand  Reduce uncertainty in future estimate of consumer demand  Encourage demand reduction  Obtain legal certainty in access to existing water sources (relating to groundwater).

In accordance with the WSDS review process, this document forms a revised WSDS for the Cann River water supply system and will replace the strategy set out in Section 8 of EGW’s overall WSDS (SKM, 2007). 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 1.1.1 Cann River Township Cann River is located at the junction of the Monaro and Princes Highway within the East Gippsland Shire, approximately 165 km east of Bairnsdale and approximately 65 km south from the New South Wales (NSW) border. Cann River is a small township with a permanent population of around 223 (ABS, 2006) people. As this is the main thoroughfare to Victoria’s far east coastline and a direct route to Canberra and NSW, increases to the population occur during major holiday periods. The location of Cann River is shown in Figure 1.

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Figure 1: Cann River Locality Map 1.1.2 Cann River Catchment The headwaters of the Cann River are within the Bondi State Forest, NSW. The river flows southwards through East Gippsland for approximately 157 km (EGCMA, 2006 p. 50) until reaching the Tamboon Inlet, a coastal lagoon that intermittently opens to the ocean. The Cann River township is located approximately 50 km from its headwaters and is located between the Lind and Alfred National Parks. The catchment area of the Cann River and its two major tributaries, Reedy and Tonghi Creeks, covers an area of 1,167km2 (EGCMA, 2006 p. 50). Public lands in the catchment include sections of the Coopracanbra National Park and Croajingolong National Park. The East Gippsland Catchment Management Authority (EGCMA) has identified management units of the Cann River and they are the Cann Estuary, Cann floodplain and the Cann Uplands (EGCMA, 2006 p. 50). The fertile Cann River floodplain supports dairying, beef cattle grazing, some cropping and viticulture (EGCMA, 2006 p. 50), while DSE’s Forest Explorer tool indicates that logging has occurred selectively over the past four decades in approximately 20% of the catchment. Although the extent of current logging activity is unknown, it is assumed to be relatively localised with limited impact on runoff. The Cann River township is situated at the southern end of the floodplain. The Cann River catchment is nearly 97% forested (Department of Primary Industries Victoria) with mixed species of eucalypt trees (Cann River Waterworks Trust, 1976). There is also a small coastal strip (Bemm to Cann River) of flat farmland and dune complex.

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2.0 Current Water Supply

2.1 Description of Water Supply System The primary water supply for Cann River comes from surface waters diverted from the Cann River. A single submersible pump on the river bed is used to pump water from the river up to a well, which is then transferred by a high lift pump station to a 1.2 km rising main. The capacity of the high lift pump station is 1.04 ML/d at 65m head. There is evidence that the river bed around the off-take is degrading and may in the future compromise the pumping arrangement. Although this is not presently an issue, it is likely that the river bed will continue to shift in the future and the off-take arrangement may need to be modified. The rising main transfers surface water to the water treatment plant that was constructed in 2007. Treatment of the raw water is carried out by a dissolved air flotation filtration process or DAFF. After the treatment plant, the water passes through a 3.4 ML shade cloth-covered clear water storage before being delivered to customers. In the past EGW has operated a drought relief bore, which is believed to be capable of providing groundwater at a rate of 2.2 L/s (0.2 ML/d), however, the pump has not been used for town water supply in 15 years. Originally the bore water passed through an aeration process and a sand filter before being fed directly into the reticulation network. This treatment infrastructure has degraded over time and is no longer used. EGW have decommissioned the connection to the reticulation as the groundwater is not of suitable quality to be fed directly in into the town supply without treatment. Therefore if groundwater is required for drought relief it would have to be trucked from the bore to the well at the river off-take, before being pumped through to the water treatment system. There is no information available on pump tests from the bore or the sustainable yield of the aquifer. EGW has now handed over the bore to East Gippsland Shire Council (EGSC) to allow DSE and the CFA access to groundwater for fire fighting purposes. A schematic of the Cann River supply system is shown in Figure 2.

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Figure 2: Cann River Water Supply System and Bore

2.2 Allocation of Water 2.2.1 Bulk Water Entitlements East Gippsland Water has a bulk water entitlement of 192 ML per year for the Cann River which is subject to the following flow sharing arrangements:  When the flow is less than or equal to 1.04 ML/day then EGW’s entitlement is equal to the flow in the Cann River upstream of the town off-take  When the flow is above 1.04 ML/day then EGW’s entitlement is 1.04 ML/day.

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=2383&state=V&classNum=G35&sea rchCode=475083 (page 2354). 2.2.2 Licensed Private 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 for Cann River is shown in Table 1.

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Table 1: Number and Volume of Licences issued for the Cann River (SRW, 2009) Number of Volume licences (ML) Direct Pumping 6 387 Stock and Domestic Licences 2 4.4 Bulk Entitlements (EGW) 1 192 Dairy 1 2.2 Total 10 585.6

From Table 1 it can be seen that the volume of water available to private diverters in the Cann River is 393.4 ML/year. EGW makes up the remaining licensed volume of 192 ML/year with their Bulk Entitlement. The majority of the private diversions are for irrigation, which takes place from November to May. The rules state the following:  All active diversions are metered in these catchments  Due to low numbers of irrigators, a simple roster applies only to the Cann River. Management is by site inspection and liaison with customers  Restricted irrigation use applies when the Cann River gauge at Weeragua (West Branch) 221201B falls below 8 ML/day. Currently there are only two active irrigators; when restrictions are called only one irrigator per day is allowed. Total irrigation bans apply on the Cann River when streamflow falls below 4 ML/day.

If the above rules are enforced, EGW’s surface water supply for Cann River should not be compromised by upstream diversions during low flow periods. 2.2.3 Groundwater Licence EGW does not hold a formal licence for the drought relief bore at Cann River. In the event of this bore being required for drought relief, EGW would need to seek temporary approval from the licensing authority (in this case Southern Rural Water).

2.3 Level of Service Objectives EGW has previously defined the following level of service objectives for water supply reliability:  Moderate restrictions (Stages 1 & 2) are not desired more frequently on average than 1 year in 10  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 Cann River is currently subject to Permanent Water Saving Rules (PWSR), which are being applied as part of a Victoria wide strategy. PWSR are part of a Victoria-wide strategy designed to help residential and commercial water users save water by adopting permanent water saving habits.

2.4 Historical Water Restrictions During the 1982/83 drought an emergency groundwater supply bore was constructed in the Cann River Caravan Park, but was only used after the drought had broken, due to the poor water quality of the initial rainfall-runoff event. No restrictions were put in place during this drought event. Voluntary restrictions were imposed in March and April 1998. Although flows remained at 2-7 ML/day during this period, the low flows resulted in algal growth on the pumps, which required cleaning. Voluntary restrictions were imposed from January to May 2003 when the river dropped below 9 ML/day. (SKM, 2006) There have been no restrictions in Cann River since 2003.

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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:  Drought Response Plan for Cann River, SKM (2006)  Water Supply Demand Strategy, SKM (2007).

The reports are summarised in the following sections. 3.1.1 Drought Response Plan for Bemm River, Buchan, Cann River, Marlo, Newmerella and Orbost (SKM, 2006) Under section 78B and 78C of the Water Industry Act 1994 all corporations holding a retail water license are required to develop a Drought Response Plan (DRP) for approval by the Minister. The DRP for Cann River 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 Cann River’s water supply system and was used as a basis for the preparation of the initial WSDS in 2007. 3.1.2 EGW Water Supply and 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 Victoria’s water resources are governed by a number of regulations and legislation. The key legislation concerning this WSDS are detailed in the following sections. 3.2.1 Surface Water Caps Each Surface Water Management Area (SWMA) within Victoria is subject to a surface water cap. 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). Cann River is located within the East Gippsland Basin Catchment. The Basin was capped in 2004 (prior to the release of the Victorian Government White Paper in 2005) and is subject to water available under Sustainable Diversion Limits. 3.2.2 Streamflow Management Plans Streamflow Management Plans (SMP) 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. There is currently no SMP that applies to the Cann River. 3.2.3 Groundwater Caps Groundwater management in Victoria is undertaken geographically through the identification of a series of areas called Groundwater Management Units (GMUs). The groundwater management areas in East Gippsland can be seen in Figure 3. The three different groundwater units are:  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)  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

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 Unincorporated Area (UA) – these cover aquifers where groundwater is expected to provide little potential due to low yields or poor water quality.

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

Cann River

Figure 3: Groundwater Management Units in East Gippsland (Red: WPSA; Blue: GMA; Orange: UA) Source: http://gmu.geomatic.com.au/Default.aspx 3.2.4 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. The Cann River does not fall under the Heritage River classification and therefore is not subject to any of the above limitations under the HRA. 3.2.5 Other Legislation Some of the Legislation that should be considered in the development of any water supply solution includes:  Water Act 1989  Flora and Fauna Guarantee Act 1988  Environment Protection Act 1970  Planning and Environment Act 1987  Environment Effects Act 1978  National Parks Act 1975  Fisheries Act 1995  Wildlife Act 1975  Catchment and Land Protection Act 1994  Environment Protection and Biodiversity Conservation Act 1999

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3.3 State and Regional Strategies 3.3.1 Regional River Health Strategy Stream value for the Cann River, which supplies Cann River township, is covered by the East Gippsland Catchment Management Authority (EGCMA) Regional River Health Strategy released in 2006. The strategy outlines the value, condition and risks to each waterway. The Cann River is described as having high value streams such as the UNESCO (United Nations Educational, Scientific and Cultural Organization) Biosphere Reserve at the Tamboon Inlet and Ecologically Healthy River rating for Tonghi Creek and Cann River East (EGCMA, 2006). 3.3.2 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 (Natural Resources and Environment, 2009). The Cann River is subject to the policies set out within the VRHS.

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4.0 Water Demand This section of the report discusses the current water demand in Cann River and estimates 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. Cann River has not been subject to water restrictions in recent years and therefore recent water use data should provide a good representation of unrestricted demand. It is noted that Cann River is occasionally used as a staging point by the DSE for fire fighting activities during bushfire events in the region. This has the potential to suddenly increase the local population, sometimes significantly, and at periods when lower flows in Cann River are more likely. This has therefore been considered in assessing demand.

4.1 Current Demand 4.1.1 Historical Diversions Historical water usage data for Cann River was obtained from the 2006 DRP prepared by SKM and from EGW records. The historical annual diversion volumes, based on the available data, are shown in Figure 4.

Figure 4: Historical Diversions The diversions from the Cann River have declined over the last few years, from almost 70 ML in 2002/03 to 43 ML in 2008/09. It is understood that a number of saw mills in the area have closed in recent years and are believed to be the reason for the decrease in the diversions; however this could not be confirmed. EGW also carried out leak detection and repair works and recovered process water from the WTP. These reasons for the recent decline in demand are consistent with the customer billing data (Table 2), which showed a greater decline in non-residential demand than residential demand and with the decline in unaccounted water shown in Table 5. Due to the uncertainty surrounding recent demand trends, the long term average demand of 60 ML per year has been adopted as the unrestricted demand.

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Table 2: Customer Billing Data 2006-07 2007-08 2008-09 Number of Connections Population1 223 224 224 Residential connections unknown 130 134 Non-residential connections unknown 62 63 Total connections 189 192 197 Total Water Use Residential water use (ML) 24.0 17.7 19.9 Non-residential water (ML) 28.7 25.7 19.8 Total water use (ML) 52.7 43.4 39.7 1Based on 2006 Census data and the VIF population projections of 0.6% per annum growth 4.1.2 Monthly Water Demand The volume of water supplied from the Cann River each month over the last few years was obtained from EGW bulk water meter data and compared to the monthly demand patterns outlined in the previous DRP (SKM, 2006). The monthly demand patterns from the previous DRP provide an accurate representation of water demand and have been adopted in this WSDS. The monthly demand has been determined based on an overall annual demand of 60 ML and is shown in Table 3.

Table 3: Monthly Water Demand Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Total Demand (ML) 4.0 4.3 4.5 5.1 5.3 5.8 6.2 5.7 5.9 5.1 4.6 4.0 60.0 % of Annual 6.6 7.1 7.5 8.4 8.8 9.6 10.3 9.4 9.8 8.4 7.6 6.6 100.0% Demand (%) Unrestrictable 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 41.5 Demand (ML) Restrictable 0.5 0.8 1.0 1.6 1.8 2.3 2.7 2.2 2.4 1.6 1.1 0.5 18.6 Demand (ML)

4.1.3 Seasonal Fire Fighting Demand It is understood that the DSE uses Cann River as a staging point during fire fighting activities in the region. The exact timing and extent of these activities in recent years has not been recorded and is equally uncertain from the perspective of planning for future events. However, the impacts of climate change in eastern Victoria are anticipated to include increased frequency of bushfires and it is reasonable to assume that fire-fighting activities will continue to be an intermittent demand on the Cann River water supply system. Summer demand profiles between 2006 and 2010 were assessed and correlated with known fire events in the Cann River area. Fire threatened the Cann River area on around December 17 last year and again in early January 2010. There is also anecdotal evidence of fires during 2006/07, though these do not appear on DSE Fire Maps. Table 4 shows the weekly demands associated with known fire events near Cann River and the equivalent monthly demand if those peak demands continued for up to a month. This is compared with the actual monthly supply during the same period and the long-term averages for supply during that month.

Table 4: Water supply data during presumed fire events around Cann River Equivalent Peak Week Actual Monthly Long-term Average Fire event / date Monthly Supply Supply (kL/d) Supply (ML) monthly supply (ML) (ML) Black Saturday 264 7.4 5.2 5.7 (Feb 2009) 1 December 17 2009 128 4.0 4.5 5.8 Early Jan 2010 173 5.4 4.9 6.2 1 It is noted that Cann River was not in the immediate vicinity of the Black Saturday fires although it is likely that demand increased for reasons such as people watering their houses as a precautionary measure, DSE mobilising staff etc.

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The following observations are made in relation to the three dates identified above:  There was a large peak in weekly supply at Cann River around the week of Black Saturday (February 7, 2009), though it almost halved the following week. Table 4 shows that extended demand at the peak supply rate would have resulted in a monthly supply well in excess of the long-term average for February. However, actual monthly supply in February 2009 was less than the long-term average, suggesting lower levels of demand for the remainder of the month following the fire event. (It is understood there were no restrictions in place at this time)  The peak weekly supply around the time of known fires in December 2009 was not excessive. Monthly supply during this month was lower than the long-term average  Fires were also reported in the Cann River area in early January 2010. Both peak weekly and monthly supplies were not unreasonable for this holiday period, with monthly supply less than the long-term average  System capacity is limited to 0.8 ML/d by the treatment plant. This is well in excess of peak daily demand, calculated at around 330 kL/d. (Capacity of the town reticulation system has not been considered).

Given uncertainty around the exact timing of past fires in the region and particularly the nature and extent of activities of DSE and CFA personnel who may have been staged at Cann River, it is difficult to directly correlate water supply data with fire fighting activities. The analysis does not account for other impacts that would also have influenced the town supply figures at the time, such as water restrictions or the number of holiday visitors. It is difficult to correlate fire events with historic peak supply conditions, particularly during December and January when demand is already elevated as a result of visitors during the holiday period. The main risk to the supply system is if a fire event occurs in a dry year when the Cann River’s flows are severely reduced. The town’s water supply system currently has 3.4ML of storage which – if initially full and assuming no inflows – provides 21 days of storage at Stage 4 restricted demands or 13 days storage at the peak demand. Given the sporadic and uncertain nature of the demands placed on the Cann River water supply system by fire- fighting requirements, it is recommended that East Gippsland Water engage with DSE to establish a protocol for extended bushfire events. The system appears adequate for personnel requirements over a short term event, but should a long term presence (up to one month) be necessary, the elevated demands could draw down supply excessively. The likelihood of such an occurrence should be assessed with DSE and communication procedures put in place to ensure that long-term fire fighting operations do not impact on supply. 4.1.4 Unaccounted Water A summary of the volumes extracted from the Cann River and volumes supplied to customers was provided by EGW. They have been compared for the last three years to determine the volume of unaccounted water. The figures are shown in Table 5.

Table 5: Usage summary data Volume Volume Adjusted Accounted Volume Financial supplied to % Extracted Storage Not Billed1 Unaccounted Year customers Unaccounted (ML) (ML) (ML) (ML) (ML) 2006-07 59.7 0.5 52.7 1.1 6.4 11% 2007-08 48.7 -0.1 43.4 0.1 5.1 11% 2008-09 43.2 -0.5 39.7 0.1 2.9 7% 1 Accounted Not Billed includes water used by EGW for operational purposes The data provided by EGW shows that unaccounted water in 2008/09 was approximately 7%, which was a reduction on the two previous years which had 11% of unaccounted water. These losses are consistent with the losses across EGW’s entire area of service, which was reported in their 2008/09 Annual Report as 8.5%. The target set in EGW’s Water Plan is to reduce unaccounted water to 10%. Losses are less than the industry average of 9.8% in Victoria and within the range (2.8% to 16.8%) reported by other water corporations in the State (source: Water Performance Report, Essential Services Commission, April 2010, p70).

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4.1.5 High Water Users There were 6 customers that used over 1 ML of water in the 2008/09 financial year and their water usage is shown in Table 6.

Table 6: High Water Users in Cann River Customer Type Water Use (ML) % of Total Demand 1 Non-Residential 2,1 5.4% 2 Non-Residential 1,1 2.8% 3 Non-Residential 1,1 2.8% 4 Non-Residential 1,0 2.6% 5 Non-Residential 1,0 2.6% 6 Residential 1,0 2.6%

In the 2008/09 financial year there were 64 non-residential customers in Cann River, who used a total of 19.5 ML of water. This accounts for 50% of the demand in Cann River.

4.2 Forecast Water Demand To predict future water demand in Cann River, the likely trends in population have been reviewed to estimate future population and water use. 4.2.1 Census Data The population of Cann River declined between the 1981 and 2001 census from 345 to 229 people (based on people counted in Cann River on census night) (SKM, 2007). This suggests a 34% decline in population over this period. In 2006, 214 people were counted in Cann River on census night, while 226 people said their usual place of residence was Cann River (ABS, 2006). 4.2.2 Victoria in the Future Data The Victoria in Future (VIF) population projections released in 2008 suggest an overall increase in population throughout the East Gippsland Region. As Cann River 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 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% and 2.5% (SKM, 2007). 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). Given that the statistical balance is likely to be the most appropriate data available for estimating future population in Cann River, a growth rate of 0.6% per annum between 2006 and 2026 could be applied to Cann River. Beyond 2026, population is expected to increase at a lower rate, however there is no data predicting what this lower growth rate may be. To take a conservative approach, the growth rate of 0.6% per annum was extended out over the entire 50 planning horizon, resulting in a population of 316 people in 2060. 4.2.3 East Gippsland Shire Council There was no information on population projections in Cann River available from Council. 4.2.4 Summary of Demand Projections Based on the information presented above, it is likely that the population in Cann River will not grow significantly over the planning horizon. The census data suggests that the population has been declining over the last few decades, while the VIF data predicts increases over the next 20 years. It has been assumed that there will be no significant increase in demand over the planning horizon. If population growth consistent with the VIF projections was experienced in Cann River, the water demand in 2060 would be 82 ML.

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5.0 Demand Management

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 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 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:  The introduction of a mandatory water efficiency labelling for appliances (commencing 2006) under the national Water Efficiency Labelling and Standards Scheme (WELS)  The introduction of rising block tariffs, which result in higher charges for high water users  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 Cann River.

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.

Monthly demand patterns outlined in 2006 DRP will be used in this study as they are most likely to represent unrestricted demand patterns. The unrestricted annual demand will be broken down by month based on this demand pattern.

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 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:  A 25% reduction in per capita demand by the year 2015 relative to 1990s average demand  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. East Gippsland Water will continue to implement its waste minimisation strategy which includes:  Working with major customers to minimise their water waste  Target significant sources of unaccounted for water throughout the system  Continue leak reduction program.

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:  The State Government will extend its existing water savings behavioural change program until 2015 – This program is still running  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  The State Government will reform the water component of the 5-star building standard to make it performance based  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

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 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  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  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  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 Risks to Reliability of Supply There are a number of factors that can impact on the future reliability of surface water catchments including:  Reduction in the volume of surface water available for extraction due to climate change  Impact of bushfires on the catchment hydrology  Impact of logging on the catchment hydrology.

These issues are discussed in the following sections. 6.1.1 Impact of Climate Change The greatest concern for Cann River’s water supply system relating to climate change is a significant reduction in the volume of surface water available for extraction. 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 stream flow 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, but uses a medium emissions scenario only to formulate runoff scenarios. Cann River is not covered by the study area of either report but is close to the boundary of the SEACI region. Changes in runoff have therefore been sourced from the SEACI report. The percentage change in modelled mean annual runoff for Cann River (~2030 relative to 1990) is projected to be -3.0% for the median scenario and -10.1% for the dry scenario. The CSIRO report states that: “Almost all the catchments available for model calibration are in the higher runoff areas in the southern and eastern parts of the SEACI region. Runoff estimates are therefore generally good in the southern and eastern parts of the SEACI region but comparatively poor elsewhere.” The dry scenario has been selected as the most prudent scenario (i.e. a -10.1% 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: 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 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 2010 when the additional data is released. 6.1.2 Step Change It is possible that the low flows that have been experienced since 1997 represent a permanent step change (DSE, 2000). SEACI will be conducting research over the next three years to investigate the reasons for the recent dry conditions and to 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. A streamflow gauge just downstream of the off-take for Cann River was active between 1979 and 1989, however is currently inactive and therefore does not provide an indication of how much current flows have decreased compared to the historical average.

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Approximately 23 km north of Cann River township, the river splits into an east and west branch. There are longer periods of streamflow gauging on these branches of the river as indicated in Table 7.

Table 7: Streamflow Gauging on the Cann River Gauging Station Start or Record End of Record Current State Cann River (east branch) at Weeragua 24/10/1972 25/08/2009 Active Cann River (west branch) at Weeragua 22/02/1957 21/09/2009 Active Cann River downstream of Cann River 27/07/1979 09/01/1989 Inactive

The annual streamflow for the two upstream gauging stations is shown in Figure 5 and Figure 6 for the east and west branch of the river respectively. The data shows that both branches of the river have experienced over a 60% reduction in streamflow since 1997.

Figure 5: East Branch Streamflow Record

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Figure 6: West Branch Streamflow Record Streamflow records of the two upstream gauging stations were also compared to the streamflow downstream of the off-take for the years when the downstream station was in operation. There was a strong correlation during the wet years, however during the drier years there was a more pronounced decrease in streamflow at the downstream gauging station than at the two upstream gauging stations. This disparity is likely to be due to losses – such as from seepage and evaporation, as well as extraction – being a greater relative proportion of total streamflows. It is therefore considered that the upstream gauges are not accurately representative of low flow conditions, and is recommended that East Gippsland Water consider re-establishing the downstream gauge prior to next summer in order to better record flow conditions. 6.1.3 Impact of Bushfires Bushfires in forested catchments have the potential to significantly impact runoff and therefore streamflows over time. Runoff after bushfires initially increases in the first few years until vegetation starts to re-grow, when runoff starts to decrease. The maximum reduction in runoff generally occurs approximately 10-30 years after the fire, before increasing back to pre-fire levels. The Cann River catchment is predominately forested with mixed species of eucalypt trees (Cann River Waterworks Trust, 1976). The response of catchments to bushfires varies with different vegetation types. This relationship between stream runoff and recovery for different species is shown in Figure 7.

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Figure 7: Estimated reduction in streamflow due to bushfire (Hill et al, 2008) Previous Bushfire Events The Cann River catchment was impacted by bushfires in 2002/03 however it is thought that the impact was very minor (EGW, 2008). There were fires in the area during the 2006/07 and 2009/10 bushfire seasons however these fires did not burn the catchment. It has been assumed that runoff from the Cann River catchment is not currently experiencing impacts from bushfires. Proposed Fuel Reduction DSE is proposing to undertake fuel reduction burns over the next 3 years that will impact on 31% of the Cann River catchment. The proposed burns are located in the higher yielding portion of the catchment and EGW has requested that DSE implement a regime that achieves a balance between fuel reduction and water quantity without compromising on water quality. Runoff impacts from fuel reduction burning are expected to be minor and do not need to be considered in the WSDS. 6.1.4 Forestry Areas within the Cann 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. The previous WSDS concluded that the impact of this logging on the off-take would be relatively small, provided the logging was dispersed across the catchment (SKM, 2007). Any increase in logging area will have a detrimental impact on streamflow. Continued logging will impact upon the streamflow within the Cann River. To improve water supply reliability, it is recommended that EGW continue to seek a reduction in the area to be logged within Cann River’s water supply catchment. 6.1.5 Water quality It is noted that the impact of stock watering on water quality is potentially more significant during periods of low flow, with increased turbidity and contamination more concentrated while passing volumes are low. This is also potentially compounded by elevated stock activity if water supplies are generally limited by dry conditions. It is recommended that EGW engage with the EGCMA to address possible water quality impacts from stock activity in the catchment to ensure that supply to Cann River is not jeopardised by declining water quality.

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6.2 Future Reliability of Groundwater There is a drought relief bore in Cann River that has been used in the past to supplement the town’s water supply during times of low flow in the river. The bore has not been used in 15 years, though EGW have now refurbished and donated the bore to the township to supply DSE and the CFA with water for fire fighting purposes. A desktop groundwater review was completed and based on the information available, it is possible that groundwater from the existing bore could provide a reliable source of groundwater for Cann River. Further investigation would be required to confirm this. It is likely that the groundwater will contain iron and require some treatment to ensure it is suitable for potable uses. From a hydrological perspective, the water in both the Cann River and the surrounding groundwater systems are the same. During dry periods of the year, it is groundwater discharge that provides most or all of the water present in the river. Therefore, any increasing in the frequency and severity of drought that affects the surface water system can be expected to have a long-term impact on groundwater levels as well.

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7.0 Current and Future Reliability of Supply

7.1 Reliability of Supply Current supply planning practice for small towns is to consider the last 12 years of data when assessing future reliability of supply under a “step change” scenario. The streamflow gauge at Cann River was out of operation until late 2009 and hence there are no accurate flow records available for this period in the vicinity of the off-take. Given the absence of recent data or an indicative low flow period by which to derive a meaningful streamflow correlation, modelling is considered to be of little value in assessing Cann River’s future water security. It is however suggested that during the next review of this WSDS, flow records from the recently installed hydrographic station be reviewed to determine if a suitable low flow period has been recorded that could be used to derive a correlation between climatic conditions and streamflow. It may be possible to extrapolate this back over the previous 12 years. While this would give some indication of reliability of supply, it would still be limited by the length of the data set and would therefore be subject to significant uncertainty. In the absence of modelling, the following information was considered when evaluating the likely reliability of the Cann River water supply system:  Annual streamflows under the high climate change scenario are expected to reduce by 10.1%, while a step change scenario could see a more severe reduction of 62% (reductions are anticipated to be greater during summer)  The river has run dry twice in the last four years including a short duration in January 2010  Fires near Cann River during January 2010 resulted in DSE mobilising a large number of staff into the town. The town supply was used for fire fighting purposes, and this resulted in tripling of demand. Irrigation extractions also increased with the threat of fire  Historical restrictions have only been imposed twice (1998 and 2003)  Current storages could supply approximately four weeks of demand under Stage 4 restrictions  Future growth in demand is expected to be moderate in relation to average streamflows  There is currently no formal backup groundwater supply  Groundwater supplies are considered to be currently available but long term sustainable extraction limits are not known and demand for the resource is expected to come under increasing pressure in a drying climate. Consideration of the above data suggests that there is much uncertainty regarding the ability of Cann River to be a reliable supply source into the future. A review of current water restriction trigger levels and identification of available backup supplies and strategies is therefore required to determine the consequence of system failure. This review is presented in Section 8 and should inform decisions on potential alternative supply or demand management strategies.

7.2 Review of Restriction Triggers 7.2.1 Existing restriction triggers The current restriction triggers for Cann River are shown in Table 8. The trigger levels would require Voluntary and Stage 2 restrictions to be applied when flow drops below the trigger level and flow is expected to continue to decline. The Stage 4 trigger level corresponds to the average daily demand (SKM, 2006).

Table 8: Restriction Triggers Flow in Cann River Upstream of Stage of Restrictions Off-take (ML/day) 8.0 Voluntary 4.0 Stage 2 0.3 Stage 4

The restriction triggers were set as part of the previous DRP (SKM, 2006), to provide four weeks of supply under Stage 4 restrictions, based on a yearly demand of 62 ML. The time between each restriction level is approximately 10 days in the absence of rainfall.

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7.2.2 Suitability of Existing Trigger Levels Behavioural simulation analysis using a REALM model was undertaken in the previous DRP (SKM, 2006). A medium climate change scenario (5% reduction in streamflow) and a continuation of low flows (41% reduction in streamflow) were both assessed and it was concluded that flows in the Cann River were sufficient to supply Cann River without restriction over the planning horizon. The conclusion was based on streamflows rarely dropping below 1.04 ML/d which would limit extractions under the existing bulk entitlement conditions. This streamflow is however well below the existing trigger level for voluntary restrictions in Cann River which is set at 8ML/d. Although historical streamflow data is limited, the records that are available indicate that streamflows have regularly dropped below 8 ML/d which suggests that maintaining this trigger level would result in the township being regularly requested to comply with voluntary restrictions (the actual frequency of voluntary restrictions cannot be accurately predicted due to the limited historical streamflow data set). The frequency of voluntary restrictions is likely to be increased via the impacts of a drier climate which was recently highlighted when the Cann River ran dry for a number of days in early 2010. Furthermore, while current climate change projections are based on a reduction in annual streamflow, seasonal variations in streamflow are yet to be assessed in detail. If streamflow reductions are greater in summer than winter, the frequency and duration of low flow periods could be even greater than would be predicted by simply applying the annual reductions across a historical record. It is also considered that the current restriction triggers provide insufficient time for community adjustment. Streamflow records indicate that flows in the Cann River recede quite rapidly during extended periods of no rainfall, this combined with absence of a major bulk storage means that available supply can be quickly exhausted. Assuming no rainfall or additional supply augmentation, the system could maintain supply for approximately 2 weeks following the onset of voluntary water restrictions until supply drops below demand and a further 4 weeks (assuming summer demand under Stage 4 restrictions) until the bulk storage (3.4ML) is exhausted. Low flow events, similar to the flows experienced in January 2010, could therefore have a serious impact on security of supply and the community may have little time to adjust to a severe water shortage unless a suitable back up water supply is available. It is recommended to further consolidate the trigger levels to two, Voluntary and Stage 4. It is desirable to have voluntary restrictions invoked sufficiently in advance of Stage 4 restrictions to provide the community advance warning of more severe restrictions and to reduce demand so that Stage 4 restrictions can be deferred or avoided. 7.2.3 Revised Restrictions It is considered that the existing restriction trigger levels should be revised in the interim until a suitable supply augmentation option can be implemented. A range of options for supply augmentation are discussed in Section 8 in which short term and long term amendments to the Cann River DRP are also proposed.

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8.0 Alternative Water Supply Options There is uncertainty surrounding the ability of the Cann River to meet demand over the planning horizon. This uncertainty is due to a lack of understanding of historical streamflows and the seasonal effects of climate change on future streamflow. The best way to assess this impact is to assess the last 12 years of data, which is not available in this case. It is possible that low flow events will become more frequent in the future and considering that Cann River only has enough storage in the system to provide four weeks of restricted summer demand, alternative water supply options have been identified. Based on historical observations of flow in the Cann River, an alternative supply will only be required very infrequently and for a short period. As such, options that require large upfront capital investment, such as desalination, water recycling, rainwater and stormwater harvesting, have not been discussed. In addition to the short term drought relief options identified, demand management and water loss reduction measures should continue to be pursued by EGW to further reduce demand for potable water. These initiatives are discussed in this chapter.

8.1 Short Term Drought Relief 8.1.1 Qualification of Rights on the Cann River EGW’s license condition already allows access to all flow in the river when the passing flow is less than 1.04 ML/day. As such there is no additional water to be accessed during drought periods. 8.1.2 Water Trading There are other users that extract water from the Cann River upstream of the EGW off-take and there may be the opportunity to transfer or exchange some of these bulk entitlements. The volume of licensed private diversions from the Cann River is 393.4 ML/year (SRW, 2009). The rules relating to these diversions state that the water can only be extracted if the flow is above 8 ML/day. It is not known if low flow events in the Cann River are more heavily influenced by rainfall or by upstream extraction and it is therefore uncertain if this option would provide significant benefits. In addition, it is likely that future low flow events will be more heavily influenced by climate change than by any other factor. As such, this option has not been discussed further in this WSDS. 8.1.3 Raw Water Storage There is currently 3.4 ML of storage capacity in the Cann River water supply system, which provides approximately 2 weeks of peak, unrestricted summer demand or 4 weeks of restricted demand (Stage 4). A new raw water storage could be constructed to provide additional emergency supply that could be drawn on during times of low river flows or as a supply for fire fighting during bushfire events. The storage would also result in less frequent water restrictions for the community by allowing trigger levels to be storage based rather than streamflow based. The cost of this infrastructure is significant and the proposed 10 ML storage at Omeo is estimated to cost $800,000. This would provide 50 days supply to Cann River at average non restricted summer demand. Based on observations of historical flow events, cease-to-flow periods in the river are expected to be infrequent and relatively short in duration. Therefore, alternative supply options with relatively significant capital investment (such as a new storage) are not considered cost effective in comparison to the alternative short duration drought relief measures discussed above. Whilst this option is not considered cost effective purely from a drought relief perspective, it may prove an attractive option when the benefits for fire fighting supply are also considered. During the 2009/10 bushfire season DSE undertook fire fighting operations in and around Cann River. Given that climate change is expected to result in more frequent and severe bushfires in the future, it is reasonable to assume that this situation will occur again over the planning horizon of this WSDS. Fighting bushfires places demands on the supply system at a time of year when low flow events are most likely to occur and a raw water storage would provide DSE with a more reliable source of water for fire fighting operations.

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However, despite the benefits of a new raw water storage, it is recognised that the cost would be high and is unjustified in comparison to alternative options to improve reliability of supply. EGW also recently donated the existing bore in the Cann River caravan park to the DSE as a water resource for fire fighting. In the event that majority funding for an additional storage could be acquired from external sources, this would be a preferred system augmentation. This is presently considered unlikely, so this option has not been considered further at this stage. 8.1.4 Water Carting from Other Rivers Water carting would only be required infrequently and it is likely to be more cost effective than investing in large infrastructure that may be used infrequently or not at all. Carted surface water could either come from Bemm River (30 km) or Wigan (30 km). At present, carted water would have to be unloaded into the existing river intake structure at Cann River in order to be pumped up to the treatment plant. However, this structure has a high rate of loss as a consequence of leakage through the timber walls. If treatment and storage capacity permits, it is possible that water carted from Bemm River could be taken from the clear water storage. This would avoid treatment requirements and losses in the river intake well at Cann River, as carted water could be unloaded directly into the clear water storage. In the event that Bemm River did not have sufficient capacity to provide treated water, water carted from the raw water source would require treatment at Cann River. In order to optimise the efficiency of water carting, it would therefore be desirable to locate a storage tank alongside the treatment plant to enable the trucks to unload without losses. While this option ensures that the township does not run out of water, it is not considered an appropriate option prior to mandatory water restrictions. It may however be possible to make the Stage 4 restriction trigger less conservative with the knowledge that water carting is a viable short term option. 8.1.5 Pump from Existing Bore An emergency groundwater supply bore was constructed in the Cann River Caravan Park during the 1982/83 drought. There was an aeration process and a sand filter to treat the groundwater before being fed into the reticulation network, though the bore hasn’t been used in a number of years and the treatment infrastructure has significantly degraded. As such EGW have decommissioned the connection from the bore to the reticulation system. The bore has recently been refurbished and donated to EGSC to enable use by the DSE and the CFA as a supply for fire fighting. A desktop groundwater review was completed and based on the information available it is possible that groundwater from the existing bore would still provide a suitable emergency water supply. Further information is provided in Appendix A. The following steps would need to be undertaken to utilise groundwater from the existing bore:  Obtain and review any other records EGW may have on the bore, its construction, and historic performance (e.g., bore log, pump test records, any historic pumping records - especially from the 2009 drought, etc)  Conduct a hydrogeological assessment to assess bore performance. The assessment would also include research on other groundwater users in the area, so that potential impacts to these users could be evaluated  Discuss and formalise access arrangements with EGSC and SRW. As the bore has been transferred to EGSC, licence requirements would need to be determined and priority access agreed in the event that emergency supply requirements coincide with fire-fighting needs  In the event that a permanent licence is required, submit an application to SRW for the proposed groundwater use (SRW has indicated that the initial fee for assessing a licence application is $10,000, with an ongoing fee of $200 per year if approved).

With the treatment infrastructure associated with the bore to be decommissioned, EGW will lose its ability to supply groundwater directly into the distribution network. Water from the existing bore would therefore need to be carted to the river intake well in order to be treated before entering supply. This would require a new storage tank alongside the treatment plant to minimise losses from the existing intake. It is assumed that the tank would only need to be the size of one truck load (no more than 30 kL/d at an approximate cost of $10,000).

9 September 2010 24 Cann River Water Supply Demand Strategy AECOM

8.1.6 Pump from New Bore As an alternative to carting water from the existing bore at the Cann River Caravan Park, it may be feasible to construct a new bore adjacent to the treatment plant, or along the route of the intake pipeline, so that carting can be avoided. Drilling a new bore may also provide better quality but hydrogeological testing is required to ascertain this. Cann River is in an Unincorporated Area for groundwater, which means EGW could apply for a licence for a new bore. This would require the following actions and costs:  EGW would need to undertake a hydrogeological assessment to assess aquifer characteristics and yield, as well as potential impacts on any other groundwater users, in order to submit an application for a groundwater licence  Southern Rural Water has indicated the fee for assessing the licence application is $10,000, with an ongoing fee of $200 per year if approved  Drilling a bore, once approved, is estimated at approximately $75,000 (inclusive of hydrogeological assessments). 8.1.7 Conversion of the Clear Water Storage to a Raw Water Storage The existing clear water storage is covered only in shade cloth, with a resulting risk that water quality following treatment is at some risk of deterioration. Construction of a new clear water tank (and re-routing of some pipelines) could allow the clear water storage to instead be used as raw water storage. This would provide better protection of water quality post treatment while also providing a location to unload carted water. The new tank should be sized for at least the peak day demand (estimated at 330kL) in order to balance flows from the treatment plant and provide a small buffer in the event of treatment plant failure. A new clear water storage would have the benefit of protecting water quality year-round, as well as providing an additional 10% storage capacity and facilitating water carting – when necessary – via the raw water storage. Although it would provide ongoing benefits while facilitating drought relief, this option is likely to have a significantly higher cost than other alternatives. The cost to construct 330kL of storage is estimated to be around $140,000. 8.1.8 Accessing Groundwater from the Cann River (and Off-take Improvements) The Cann River is a sand bed river with a strong interaction with groundwater. During previous no-flow events EGW has gained consent from the EGCMA to excavate a pool in the river for extraction of streamflow below the river bed. For this to be considered a reliable drought supply, legal certainty regarding EGW’s rights to access this water is required. Discussions with Southern Rural Water indicated that water below the river bed would be classified as groundwater and would therefore require a licence. It is likely that a streambed alteration permit would also be required from EGCMA. While such a permit was granted in early 2010, there is no guarantee that this will be the case for future droughts. It is also noted that the existing river intake well has deteriorated and may require modification or replacement in the near future. An opportunity may therefore exist to undertake improvements to the river off-take for Cann River that also secures access to the groundwater below the river bed for drought relief. EGW should consider the use of spear point pumps as part of an upgrade to the river off-take. It is anticipated that a shallow bore in the river bed would be required. It is expected that this proposal would involve the following stages:  Consult with Southern Rural Water to clarify access arrangements during cease to flow events  Discuss the proposal with the EGCMA to understand requirements for approval to modify the existing off- take  Undertake preliminary design and cost estimates  If the proposal is viable from a cost, regulatory and statutory perspective, it may be feasible to stage applications such that EGW maintains its entitlement during periods of flow, but must apply to SRW in the event of no-flow conditions.

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Studies to assess impacts on river ecology, morphology and hydrogeology will likely be required to inform approval applications. As the cost of these studies may make this option unfeasible, EGW should engage both Southern Rural Water and the EGCMA at the beginning of this process. As part of any application EGW should consider the use of spear point pumps as opposed to excavating a pool in the river bed. This will ensure that any environmental disturbance associated with this option is minimised. Although constructing a shallow bore may impact on the river bed in the short term, any impacts would be significantly less than the alternative of excavating a pool during periods of drought. Spear point pumps may have the further benefit of providing an additional filter barrier, reducing the turbidity of water delivered to the treatment plant with potential operating cost savings. However, the ongoing maintenance cost of the spear point pumps relative to the existing pumping arrangement would also require consideration. 8.1.9 Option Comparison A new raw water storage would enhance the Cann River system by increasing overall capacity and providing a source point for fire fighting activities. However, in the absence of external funds this is not considered feasible. Similarly, the costs associated with construction of a desalination plant or a new clear water tank and conversion of the existing clear water storage to a raw water storage is difficult to justify. Given that the existing river intake well is likely to require major improvement in the future, it is recommended that EGW investigate the opportunity to modify the intake so that groundwater can be accessed during periods of low or no flow. While the regulatory arrangements for this option require discussion with both SRW and the EGCMA and will likely require application for a groundwater licence, it is considered that the dual benefit of intake improvements and provision of an emergency supply during drought warrant pursuit of this option. The previous DRP (SKM, 2006) for Cann River reported that two 12kL tanker loads would be required to maintain the minimum requirement of 60 L/customer/day. To deliver Stage 4 restricted demand of 70kL/d, three 25 kL tanker loads would be required. If it is assumed that losses in the existing intake well on the river are as high as 50%, the number of tanker trips required would double. In the absence of an upgraded intake well, a new raw water tank or clear water storage at the treatment plant would avoid the losses of the river intake well when unloading carted water. It is estimated that the costs associated with the construction of a new clear water tank (330kL) may be in the order of $140,000 while a 30kL raw water storage would be significantly cheaper at around $10,000. The costs associated with a raw water tank (30kL) would be recuperated during a single drought event during which carting is required for an extended period (2 weeks). A new bore adjacent or close to the treatment plant would have a high cost associated with preparatory studies, licence fees and construction (approx. $85,000). Although this would avoid the need for carting of water from the existing bore, it is unlikely that this would be cost-effective unless the existing bore is shown to have insufficient yield as an emergency supply. In this instance, carting from other destinations is likely to be more cost-effective given the anticipated frequency of such events. A summary of the short-term drought relief options is provided in Table 9 and a list of prioritised actions as follows:  Pursue option to upgrade existing river intake to incorporate spear point pumps accessing river bed groundwater  In the interim, or in the event that new intake works are infeasible, formalise access arrangements and licence requirements for groundwater extraction from DSE’s bore  Consider a clear water storage or raw water tank at the treatment plant, in order to enable carted water (from DSE’s bore or neighbouring supply systems) to be unloaded without losses.

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8.2 Demand Management There are 64 non-residential customers in Cann River, accounting for approximately 50% of demand (19 ML/year). There are likely to be some opportunities for water savings amongst these customers, whether it is through the installation of water efficient devices such as shower heads, potable substitution with rainwater or other water sources, leakage detection and education awareness programs. It is difficult to quantify the savings associated with reducing demand from the top water users and as such it is suggested that EGW undertake a demand analysis and audit high water users to determine the feasibility of these water savings.

8.3 Water Loss Reduction Data provided by EGW shows that unaccounted water in 2008/09 was approximately 2.9 ML, which is about 7% of total extractions (refer to Table 5). The clear water storage is covered and it is expected that most of the unaccounted water can be attributed to system leakage. Water systems typically operate with up to 10% unaccounted for water and reducing losses further in an already efficient system is unlikely to be cost effective in comparison with alternative options to improve reliability of supply. However, EGW should continue to monitor losses in the distribution system to ensure they do not increase and identify any cost effective system improvements that can be made to reduce losses.

8.4 Proposed Amendment to the Drought Response Plan There is currently much uncertainty surrounding the suitability of the preferred alternative supply options. Recommendations to amend the DRP are therefore presented in two stages: Immediate – to inform the current DRP and Short Term – which recognises the need for additional investigation and a future update of the DRP. Immediate Adopt the following practice for the current DRP:  When supply from surface water streamflows drops below demand, commence pumping from sub surface flows and invoke Voluntary restrictions  When supply from subsurface flows drops below demand, commence carting from groundwater bore to shandy with water in storage  When salinity in the raw storage reaches 750mg/L TDS cease carting from bore  When the total volume of water in storage drops below 2ML, invoke Stage 4 restrictions and start carting from Bemm River to shandy with water from the groundwater bore. Note that this procedure assumes that access to subsurface flows is not restricted for either hydrogeoloical or regulatory reasons. If this occurs, EGW may elect to move straight to mandatory restrictions and commence carting. Short term (to align with Water Plan 3) Conduct hydrogeological studies to determine the reliability of sub surface flows beneath Cann River and likely water quality available from drilling a new bore. Pending the outcomes of these assessments, review the restriction triggers in the DRP to determine what supply augmentation options would be required to allow EGW to meet its level of service objectives (this includes defining a level of service objective for voluntary restrictions). This may include the identification of large scale augmentation options which should be considered for inclusion in the upcoming Water Plan.

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Table 9: Summary of short-term drought relief options for Cann River Existing Emergency Supply Proposed Enhancement Cost Benefit Recommendation Option Increased storage capacity to meet New raw water storage to increase demand during drought periods Highest cost option – would require Preferable option, though infeasible capacity to meet peak demand majority external funding for due to lack of sufficient external during drought and fire-fighting Additional source for fire-fighting implementation funding periods requirements (though existing bore already donated for this purpose) Lowest relative cost (~$10,000) for Reduces number of tanker loads to Lowest cost option with least benefit New raw water tank (~30 kL) to raw water storage would be transfer emergency supply – recommended due to the high avoid losses that would currently recuperated within one extended cost or uncertainty of alternative Water carting from neighbouring occur in the existing river intake well drought event by reducing the No benefit during non-drought options supply systems; number of required tanker loads periods Reduces number of tanker loads to Tank would need to have capacity OR transfer emergency supply (could for peak day demand (~330 kL). Convert existing clear water storage unload into raw water storage) Cost dependent upon required Ongoing benefits are not sufficient to Water carting from existing bore at to a raw water storage and construct alterations to pipe and pump justify high cost Cann River Caravan Park a new clear water tank (~330 kL) Increases storage capacity by ~10% arrangements, but considered high Enclosed clear water storage relative to other options protects treated water quality High cost option to investigate, apply Considered too high cost at this for licence and construct bore stage; may be justified in the event Construct new bore adjacent to (~$85,000) Would eliminate need for water of continuing low flows in the future deliver emergency groundwater carting as emergency supply supply directly to treatment plant Ongoing fee ($200 per year) (assuming sufficient yields) (Would complement any short-term incurred irrespective of whether bore changes without making them utilised redundant) Costs are largely offset by the need Subject to regulatory to upgrade the existing intake in the arrangements, this option is Accessing groundwater from Cann Existing ageing infrastructure is near future preferred for providing River by making modifications to replaced while providing access to improvements to infrastructure as existing river intake, potentially with Uncertain licensing arrangements groundwater when needed for well as a potential drought relief installation of spear point pumps require discussion with SRW and emergency drought relief EGCMA. Environmental studies supply could be required at substantial cost.

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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 Although historically reliable, there is some uncertainty surrounding the ability of the Cann River to meet demand over the planning horizon. This uncertainty is due to a lack of understanding of the seasonal effects of climate change on surface water flows. It is possible that low flow events will become more frequent in the future and given that Cann River only has enough storage in the system to provide four weeks of demand under Stage 4 restrictions, alternative water supply options and recommended updates to the Cann River DRP have been identified.

10.2 Summary of Recommendations Following this update of the WSDS for Cann River, it is recommended that EGW implement all of the actions detailed in Table 10. Implementing all of these actions will be resource intensive and EGW should prioritise implementation in accordance with the action plan.

Table 10: Action Plan Action Implementation Update the Drought Response Plan for Cann River in accordance with the recommendations Immediate presented in Section 8.4. Engage with SRW and the EGCMA to determine viability of the proposal to modify the river Immediate intake arrangement, including licence requirements and extent of any environmental studies. Determine if groundwater from the existing bore is suitable for potable supply and formalise Immediate access arrangements by undertaking the following actions:  Conduct pump tests and water quality tests on the existing groundwater bore that was previously owned by EGW and was recently handed over to EGSC for fire fighting purposes.  Conduct a hydrogeological assessment to assess bore performance. The assessment would also include research on other groundwater users in the area, so that potential impacts to these users could be evaluated  Pending the outcomes of the above assessment, seek to formalise priority access to the bore during emergency supply situations via an amendment to the existing groundwater extraction licence.

Develop communication protocols with DSE for extended periods of fire-fighting activity. Immediate Continue existing leak detection programs to ensure the system operates in an efficient Ongoing manner. Continue to monitor the impacts of logging and if a long term supply shortage is anticipated Ongoing then seek a reduction in the area to be logged within the water supply catchment. Engage with the EGCMA to discuss the implications for raw water quality of Cann River’s Immediate supply from stock watering within the catchment, particularly during periods of low flow. Construct of a new raw water tank (30kL) at the treatment plant to enable carted water to be 2010 unloaded without losses. Seek to reduce current water demand by auditing high water users and identifying possible 2010/11 savings.

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11.0 References ABS (2006) 2006 Census QuickStats: Cann River (State Suburb) Cann River Waterworks Trust (1976) Report on the Cann River Water Supply Catchment Proposed for Proclamation, report for the Soil Conservation Authority and the Land Conservation Council CSIRO (2008) Rainfall-runoff modelling across the Murray-Darling Basin A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project DSE (2005) Guidelines for the Development of a Water Supply-Demand Strategy DSE (2009) Gippsland Region Sustainable Water Strategy – Discussion Paper EGCMA (2006) Protecting and Improving Our River Health: The East Gippsland Regional River Health Strategy 2005-2010, Bairnsdale. EGW (2008) Fire Plan 2009-2011, letter to DSE dated 30 October 2008. Hill et al. (2008) Spatially explicit modelling of the hydrologic response of bushfires at the catchment scale. Natural Resources and Environment (2009) Healthy Rivers, Healthy Communities and Regional Growth – Victorian River Health Strategy. SEACI (2008) Future Runoff Projections (~2030) for Southeast Australia SKM (2006) East Gippsland Water Drought Response Plan Bemm River, Buchan, Cann River, Marlo, Newmerella and Orbost Final 05 JUNE 2006 SKM (2007) East Gippsland Water: Water Supply Demand Strategy SRW (2009) Local Management Rules East Gippsland Basin Catchments, September 2009, http://www.srw.com.au/Files/Local_management_rules/eastgipps_local_Management_Rules_Sept09.pdf VIF (2008) Victoria in Future 2008 - Population Projections

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Appendix A

Desktop Groundwater Review

9 September 2010 A Cann River Water Supply Demand Strategy AECOM

Appendix A Desktop Groundwater Review The purpose of this evaluation is to provide some general hydrogeological considerations related to East Gippsland Water’s possible use of groundwater supplies to supplement the existing surface water supply for the Cann River area. Under drought conditions, the surface water supply may become un-reliable and groundwater is a possible supply source under these conditions. EGW currently owns and operates a groundwater extraction bore in Cann River. Due to the minimal amount of site-specific information available, this evaluation is necessarily very general. Demand In order to evaluate the feasibility of a particular water source, it is necessary to establish the anticipated water demand requirements. It has been assumed that demand is of the order of 6 ML in a month (historical average summer demand) on a short-term/seasonal basis. Ability of existing bore to meet demand Information about EGW’s existing bore at Cann River (B86148) was obtained from the SKM drought response plan (SKM, 2006) and publically available on-line databases. The bore appears to be approximately 45 m deep, screened from approximately 20 to 40 m, and appears to be screened in unconsolidated alluvial sands associated with the Cann River. No information on hydrogeological testing of the bore has been provided; nor has information about its historical performance during prior droughts (that is, was it able to satisfactorily meet demands in the past). However, the alluvial deposits of the Cann River valley are expected to have a relatively high permeability. If the bore is screened in these materials, it is likely to be able to provide sufficient groundwater to meet high volume, short duration demands. If the bore is not screened in alluvial sands, it is most likely screened in the underlying igneous (granitic) intrusives. This unit would still be able to provide groundwater, but both the permeability and the porosity (storage) would be much lower, and dependent on fractures in the rock. The ability of this formation to meet short-term demands is less certain. Except for the presence of iron (discussed further below), the quality of the groundwater pumped from the bore appears to be suitable for its intended use. Other considerations Groundwater from the existing bore is treated to remove iron. It appears that the treatment infrastructure has degraded over time and has been decommissioned. It should be noted that treatment of the iron would be necessary both to render the water potable and to protect the storage/distribution system from iron precipitation. As the bore is no longer connected to the distribution system, the logistics of water transfer would have to be assessed. If the bore has been inactive or infrequently used over an extended period of time, the bore and/or associated infrastructure may need maintenance or repair. SKM’s drought response plan (SKM, 2006) indicates the bore was not used for 12 years (prior to 2006). The pump and piping should be inspected. The bore itself may benefit from re-development to improve its performance (yield and water quality). From a hydrological perspective, the water in both the Cann River and surrounding groundwater systems are the same – rainfall/snowfall in recharge areas of the catchment. During dry periods of the year, it is groundwater discharge that provides most or all of the water present in the river. Therefore, any increasing frequency and severity of droughts that affect the surface water system can be expected to have long-term impacts on groundwater levels as well. If the existing bore is to be used as part of the water supply system, a groundwater extraction licence is required from Southern Rural Water (SRW). For any new, proposed extraction in excess of 2 ML/year, a hydrogeological assessment of the groundwater system needs to be completed and submitted to SRW as part of the water allocation application process. The evaluation would include hydraulic testing of the existing bore, estimation of sustainable yield and ability of the bore to meet the expected demand, and potential impacts of pumping on the surrounding environment (e.g. other groundwater users, nearby surface water bodies, etc).

9 September 2010 A-1 Cann River Water Supply Demand Strategy AECOM

The proximity of the bore to the river may be a limitation from a regulatory perspective in the context of pumping induced stream depletion and associated environmental concerns. However, this is complicated by the fact that EGW is permitted to extract all available water from river under low-flow conditions. The hydrogeological assessment methodology may require that one or more additional observation bore(s) be installed, with the associated cost being met by the applicant. The groundwater extraction licence application process also provides for stakeholder consultation and it should be noted that any such application may be rejected by SRW depending on the technical and regulatory context of the application, or on the basis of upheld stakeholder concerns. Possible next steps If EGW is interested in further pursing groundwater as a back-up water supply, the following steps are recommended:  Obtain and review any other records the EGW may have on the bore, its construction, and historic performance (e.g. bore log, pump test records, any historic pumping records -especially from 2009 drought, etc)  Conduct a hydrogeological assessment to assess bore performance. The assessment would also include research on other groundwater users in the area, so that potential impacts to these users could be evaluated  Submission of a water allocation application to Southern Rural Water for the proposed groundwater use.

9 September 2010 A-2