Bemm River Water Supply Demand Strategy

9 September 2010

Bemm River Water Supply Demand Strategy AECOM

Bemm 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

The information contained in this document produced by AECOM Australia Pty Ltd is solely for the use of the Client identified on the cover sheet for the purpose for which it has been prepared and AECOM Australia Pty Ltd undertakes no duty to or accepts any responsibility to any third party who may rely upon this document.

All rights reserved. No section or element of this document may be removed from this document, reproduced, electronically stored or transmitted in any form without the written permission of AECOM Australia Pty Ltd.

9 September 2010 Bemm River Water Supply Demand Strategy AECOM

Quality Information

Document Bemm River Water Supply Demand Strategy

Ref 60144336

Date 9 September 2010

Prepared by S Eldib

Reviewed by S Wallner / M Habener

Revision History

Authorised Revision Revision Date Details Name/Position Signature

A 08-Jun-2010 Draft Andrew Grant Original Signed Principal Engineer - Water B 16-Jul-2010 Final Draft for Comment Andrew Grant Original Signed Principal Engineer - Water C 09-Sep-2010 Final Issue for Publication Elisa Hunter

9 September 2010 Bemm River Water Supply Demand Strategy AECOM

Table of Contents Executive Summary i 1.0 Introduction 2 1.1 Regional Setting 2 2.0 Current Water Supplies 4 2.1 Description of Water Supply System 4 2.1.1 Overview 4 2.1.2 Method of Supply 4 2.1.3 Water Treatment 5 2.2 Allocations of Water 5 2.2.1 Bulk Entitlements 5 2.2.2 Other Licensed Diversions 5 2.2.3 Groundwater Licences 6 2.2.4 Level of Service Objectives 6 2.3 Historical Water Restrictions 6 3.0 Previous Studies, Legislation and Regulation 7 3.1 Previous Long Term Planning Studies 7 3.1.1 Drought Response Plan (SKM, 2006) 7 3.1.2 EGW Water Supply Demand Strategy (SKM, 2007) 7 3.2 Regulations and Legislation 7 4.0 Water Demand 10 4.1 Current Demand 10 4.1.1 Previous Demand Estimates 10 4.1.2 Bulk water meter data and historical diversions 10 4.1.3 Customer Billing Data 11 4.1.4 Commercial and Industrial Water Use 12 4.1.5 High Volume Water Users 12 4.1.6 Unaccounted Water 12 4.1.7 Summary of Current Demand 12 4.2 Forecast Water Demand 13 4.2.1 Previous Population Projections 13 4.2.2 Recent Census Data 13 4.2.3 Victoria in Future Data 13 4.2.4 Proposed Sewerage Scheme 13 4.2.5 Summary of future demand 14 5.0 Demand Management and Reduction 15 5.1 Measures to Achieve Demand Reduction Targets 15 5.1.1 Current Demand Reduction Initiatives (SKM, 2007) 15 5.1.2 Future Demand Reduction Initiatives (SKM, 2007) 16 6.0 Water Supply 18 6.1 Risks and Uncertainties 18 6.1.1 Impact of Climate Change 18 6.1.2 Impacts of Step Change 19 6.1.3 Impact of Bushfires 19 6.1.4 Forestry 21 6.2 Future Streamflow Projections 21 7.0 Reliability of Supply 22 7.1 Current Reliability of Supply 22 7.1.1 Review of Restriction Triggers 22 7.2 Future Reliability of Supply 22 8.0 Options for Managing Water Supply 24 8.1 Water Loss Reduction 24 8.2 Demand Management 24 8.3 Emergency Supply Options 24 8.3.1 Water Carting 24 8.3.2 Groundwater 24

9 September 2010 Bemm River Water Supply Demand Strategy AECOM

8.4 Recycled Water 25 8.5 Recommendations for Managing Supply 25 9.0 Stakeholder Consultation 26 10.0 Conclusions and Recommendations 27 10.1 Conclusion 27 10.2 Summary of recommendations 27 11.0 References 28

9 September 2010 Bemm 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 in the process of reviewing each of the water supply strategies. AECOM Australia Pty Ltd (AECOM) has been engaged by EGW to revise their existing WSDS for the Bemm River water supply system. This revised WSDS will replace the strategy set out for Bemm River in EGW’s overall WSDS (Section 14). 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.

Historically the Bemm River has proven to be a reliable supply source, which is confirmed by historical records that indicate voluntary restrictions were imposed only once since the construction of the system in 1983/84. It is understood that these restrictions were imposed not due to a shortage of supply at Bemm River, but due to the fact that much of EGW’s area of service was under threat from bushfires and many systems were experiencing water supply shortages. This has further been affirmed through analysis of historical streamflow data over the period 1975 to 2009 which indicates that there were no days when flow in the river ceased and that the minimum flow on the Bemm River recorded during this period was 35.7ML/d. Recent studies and observations have shown that the impacts of climate change have already, and will most probably continue to result in a significant reduction of flows in the Bemm River. Annual flows in the river have been reduced by approximately 38% over the last 12 years when compared to the historical long term average. Adjusting the streamflow records for Bemm River to account for this, the most severe climate change scenario yields a minimum flow record of 18.8 ML/d. This would still allow EGW to extract their full bulk entitlement of 1.47 ML/d. In addition, the predicted growth in water demand to 2055 (see Section 4.2) can easily be supplied with the existing bulk entitlement on the Bemm River (see Figure 9). The system also has a total storage capacity of approximately 12 weeks of summer demand. It was therefore concluded that EGW will continue to be able to meet their LOS objectives for Bemm River over the next 50 years even considering the impacts of climate change, past bushfires and growth in water demand. As a result, further supply enhancement will not be required. Based on the analysis undertaken and the assessment of options it is recommended that EGW undertake the following to secure Bemm River’s water supply:  Continue to monitor losses within the water supply system  Seek to reduce current water demand by auditing high water users and identifying possible savings  In times of emergency, cart water from Cann River or another nearby supply system;  Continue to monitor the impacts of logging and if a long term decline in supply is anticipated seek a reduction in the area to be logged within the water supply catchment  Update Bemm River’s Drought Response Plan.

9 September 2010 i Bemm River Water Supply Demand Strategy AECOM

1.0 Introduction 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 in the process of reviewing each of these strategies. The revision of the WSDS will be based upon new information relating to climate change, drought, bushfires, population growth and their combined impacts. WSDSs are otherwise required to be reviewed and updated at least every 5 years. Continuing dry conditions have resulted in a significant drop in streamflows throughout Victoria and East Gippsland has not been exempt from these impacts. CSIRO have determined that climatic conditions are tracking above the previous high climate change scenarios which suggests that the medium climate change scenario that was recommended by Department of Sustainability and Environment (DSE) during preparations of the earlier WSDS may over estimate long term yields. The previous WSDS for Bemm River recommended that EGW:  Reduce uncertainty in current estimate of consumer demand  Reduce uncertainty in future estimate of consumer demand  Encourage demand reduction

In accordance with the WSDS review process, this document forms a revised WSDS for the Bemm River water supply system and will replace the strategy set out in EGW’s overall WSDS (Section 6). 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 Bemm River is a small township situated approximately 120 km east of Bairnsdale and 350 km east of Melbourne. The town is located on the banks of the Bemm River adjacent to the Cape Conran Coastal Park. The 2006 census showed that Bemm River and the surrounding area had a population of around 151 people. Its location also lends itself to being a tourist destination with the population estimated to double in the January tourist season. The location of Bemm River is shown in Figure 1 as follows.

9 September 2010 2 Bemm River Water Supply Demand Strategy AECOM

Figure 1: Regional Map

9 September 2010 3 Bemm River Water Supply Demand Strategy AECOM

2.0 Current Water Supplies

2.1 Description of Water Supply System 2.1.1 Overview The Bemm River catchment covers an area of approximately 940 km2 which is largely forested with some farmland areas. The Department of Primary Industry (DPI) categorises most of the East Gippsland Basin which Bemm River falls under as covered with mixed-species forest. A schematic of the Bemm River water supply system is shown in Figure 2.

Figure 2: Bemm River Water Supply System 2.1.2 Method of Supply Water is supplied to the township of Bemm River from a permanent diversion on the Bemm River approximately 1.0 km away. The pumping station has the capacity to transfer 17 L/sec (or 1.47 ML/day) of raw water via the 150mm diameter rising main. This rising main feeds into the water treatment plant (WTP), and the treated water is stored in a 6.4 ML clear water basin which then supplies the town by gravity.

9 September 2010 4 Bemm River Water Supply Demand Strategy AECOM

2.1.3 Water Treatment In 2007 EGW commissioned a new WTP at Bemm River to improve the quality of treated water provided to the town. The new WTP uses a Dissolved Air Flotation Filtration (DAFF) process which is capable of treating raw water from the Bemm River to a standard of less than 5 NTU (Turbidity) and less than 5 Pt/Co (Colour). The WTP has been designed with a treatment capacity of 4 L/sec giving a total daily volume of 140 kL/day. The location of the WTP with respect to the Bemm River township and the Bemm River is shown in Figure 3.

Figure 3: Bemm River Water Supply Infrastructure

2.2 Allocations of Water 2.2.1 Bulk Entitlements EGW has a bulk water entitlement of 100 ML per year for the Bemm River which is subject to the following flow sharing arrangements:  When the flow is less than or equal to 1.47 ML/day then EGW’s entitlement is equal to the flow in the Bemm River upstream of the town off-take  When the flow is above 1.47 ML/day then EGW’s entitlement is 1.47ML/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=2338&state=V&classNum=G35&sea rchCode=1064675 2.2.2 Other Licensed Diversions Southern Rural Water (SRW) provides an overview of local management rules for each of their river catchments on a regular basis. The latest revision of these rules was issued in September 2009. The management rules not only provide operational guidelines, but also a summary of licences held. A summary of licences for the Bemm River is shown in Table 1.

9 September 2010 5 Bemm River Water Supply Demand Strategy AECOM

Table 1: Number and Volume of Licences issued for the Bemm River (SRW, 2009) Number of Volume licences (ML) Direct Pumping 2 62 Domestic and Stock Licences 1 2.2 Bulk Entitlements (EGW) 1 100 Total 4 164.2

From Table 1 it can be seen that the volume of water currently allocated to private diverters on the Bemm River is 64.2 ML/annum, which comprises only a small proportion of the Rivers average annual flow. EGW makes up the remaining licensed volume of 100 ML/annum with their Bulk Entitlement. 2.2.3 Groundwater Licences Groundwater is not currently used as part of EGW’s water supply for the Bemm River system. 2.2.4 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 Bemm River is currently subject to Permanent Water Saving Rules (which are being applied as part of a Victoria wide strategy).

2.3 Historical Water Restrictions The following are the historical events relating to water restrictions for Bemm River.  The water supply system of Bemm River was not commissioned until 1984 and as such was not tested during the 1982/83 drought  During the 1997/98 drought lower flows were recorded but flows still remained adequate to maintain storage levels. The lower flows did result in an increase to colour of the water  Voluntary water restrictions were introduced at Bemm River in January 2003 however triggers for restriction were not reached and restrictions were lifted in May 2003 (DPI, 2005). It is understood that these restrictions were imposed not due to a shortage of supply at Bemm River, but due to the fact that much of EGW’s area of service was under threat from bushfires and many systems were experiencing water supply shortages.

9 September 2010 6 Bemm River Water Supply Demand Strategy AECOM

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 Orbost, Buchan, Cann River and Bemm River, SKM (2006)  Water Supply Demand Strategy, SKM (2007).

The reports are summarised in the following sections. 3.1.1 Drought Response Plan (SKM, 2006) Under section 78B and 78C of the Water Industry Act (1994) all corporations holding a retail water licence are required to develop a Drought Response Plan (DRP) for approval by the Minister. The DRP for Bemm 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 Bemm River’s water supply system which was used as a basis for the preparation of the initial WSDS in 2007. 3.1.2 EGW Water Supply Demand Strategy (SKM, 2007) The WSDS prepared by SKM in 2007 is EGW’s current WSDS for all of its water supply systems and forms the basis from which this updated WSDS has been developed. The previous WSDS provides long term strategies for managing available urban bulk water supply and customer demand across each of EGW’s water supply systems.

3.2 Regulations and Legislation Victoria’s water resources are governed by a number of regulations and legislation. Some key legislation concerning this WSDS is detailed as follows. Surface Water Caps Each Surface Water Management Area (SWMA) within Victoria is subject to a surface water cap. Bemm River falls within East Gippsland SWMA. The East Gippsland SWMA is capped with water available under sustainable diversion limits. Therefore, there is scope to issue new licences up to the capped allocation. 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 4. 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.  Unincorporated Areas (UA’s) – these cover aquifers where groundwater is expected to provide little potential due to low yields or poor water quality.

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

9 September 2010 7 Bemm River Water Supply Demand Strategy AECOM

Figure 4: Groundwater Management Units in East Gippsland (Red: WSPA, Blue: GMA)

(Source http://gmu.geomatic.com.au/Default.aspx) Streamflow Management Plans Streamflow Management Plans (SMPs) 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. No SMPs have been prepared for waterways in the East Gippsland Basin (including the Bemm River). Regional River Health Strategy Stream value for the Bemm River, is covered by the East Gippsland Catchment Management Authority Regional River Health Strategy (EGCMA RRHS). The Bemm River is classified as being in ‘good to excellent’ condition within the RRHS and considered to be ‘high value’ downstream of the EGW off-take. 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 Bemm River falls under the Heritage Rivers classification, and is therefore subject to the above limitations under the HRA. Victorian River Health Strategy The Victorian River Health Strategy (VRHS) outlines the Government’s long-term policy for managing Victoria’s rivers. It includes a vision for Victorian river management, policy direction on river health issues and a blueprint to integrate all work on Victorian rivers to gain the best river health outcomes (Environment Victoria, 2009). The Bemm River is subject to those policies set out within the VRHS.

9 September 2010 8 Bemm River Water Supply Demand Strategy AECOM

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

9 September 2010 9 Bemm River Water Supply Demand Strategy AECOM

4.0 Water Demand This chapter of the report discusses the current water demands on the Bemm 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. Bemm River has not been subject to water restrictions and therefore recent water use data should provide a good representation of unrestricted demand. For the purpose of this report ‘restrictable demand’ is defined as the component of demand which can be eliminated without impacting on ones quality of life (i.e. outdoor demand) while ‘unrestrictable demand’ is largely the component of demand which is necessary for everyday life (i.e. washing, food preparation etc).

4.1 Current Demand 4.1.1 Previous Demand Estimates The DRP (2006) presented detailed demand forecasts based on historical average annual diversion rates using demand data from July 2003 to June 2005. The demands outlined in the DRP are shown in Table 2.

Table 2: Monthly Water Demand (based upon the DRP - SKM, 2006) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Total Monthly Demand (ML) 2.3 2.7 2.2 2.5 2.5 3.2 4.1 4.1 4.5 3.4 2.4 1.8 35.7 % of Annual Demand 6.3 7.7 6.0 6.9 7.1 8.8 11.4 11.6 12.5 9.6 6.8 5.1 100.0 Unrestrictable Demand (ML) 1 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 21.3 Restrictable Demand (ML) 1 0.5 1.0 0.4 0.7 0.8 1.4 2.3 2.4 2.7 1.7 0.7 0.1 14.5 1 Figures have been rounded therefore may not add up to total monthly demand In relation to these demand estimates SKM (2006) stated that: “The long term average annual diversion from Bemm River was estimated to be around 36 ML per year” This included 10 ML/yr of water which was diverted to the town for the disinfection process and returned to the river. This volume has significantly reduced with the commissioning of the new WTP in early 2007. It should be noted that Bemm River has a caravan park with over 100 sites as well as other holiday accommodation available and the Bemm River hotel. It is estimated that the peak seasonal population is likely to double that of the resident population. This is observed in the increase in demand over the summer period. 4.1.2 Bulk water meter data and historical diversions Complete bulk water meter data from EGW’s SCADA system is not available for the 2006 to 2009 period due to the raw water meter not being available prior to commissioning of the WTP in 2007 and a faulty flow meter on the town supply in 2008 which has since been rectified. To assist with establishing an appropriate demand profile for Bemm River recent bulk meter data from EGW’s annual reporting has been extracted. The volume of bulk water diverted and treated for the last seven years is shown in Table 3 and in Figure 5.

Table 3: EGW’s Annual Reporting Data Meter Readings (ML) 02/03 03/04 04/05 05/06 06/07 07/08 08/09 Average Bulk Water Sourced 33.6 35.6 33.0 33.8 33.1 25.3 18.8 30.5 (Diversions)1 Water Consumed1 17.3 18.8 16.6 16.7 17.8 12.9 17.9 17.5 1 Data provided by EGW From Table 3 it can be seen that the average volume of bulk water sourced over the seven years was 30.5 ML, but that diversions had reduced substantially since the commissioning of the new WTP which resulted in a significant reduction in the consumption of process water (see previous section).

9 September 2010 10 Bemm River Water Supply Demand Strategy AECOM

Review of annual reporting data indicates that there was an average loss of 15.7 ML between the bulk water sourced and the customer billing data (between 2002 and 2008) and that this was reduced to 1 ML in 2008/2009.

Increase in New Treatment Plant bleed water Commissioned

Figure 5: Historical Diversions from Bemm River (96/97 FY to 08/09 FY)

Note - diversion figures between 1996 and 2001 are only estimates that have been based on Figure 6-4 of the previous WSDS (SKM, 2007) Figure 5 shows an increase in historical diversions from 2000 to 2003 due to an increase in the bleed water through the system to improve disinfection and is not due to an increase in household consumption. The significant decrease post 2007 is largely the result of the commissioning of the new treatment plant in early 2007. As a result of these events it is not possible to assess long term trends in water diversions, however consumptive data indicates minimal change in water consumed (excludes losses prior to the town meter) with a long term average consumption of 17.5 ML/yr. 4.1.3 Customer Billing Data EGW has provided water consumption and connection data for the Bemm River water supply system to assist with determining residential per capita water use. A summary of data provided by EGW is shown in Table 4.

Table 4: Water Consumption and Connection Data

06/07 FY 07/08FY 08/09FY Residential Connections 89 89 89 Non Residential Connections 8 8 8 Total Connections 97 97 97 Residential Demand (ML) 12.6 9.0 12.9 Non Residential Demand (ML) 5.2 3.9 5.0 Total Demand (ML) 17.8 12.9 17.9 Residential Water Use (L/capita/day)1 220.4 157.4 225.6 1 Calculating assuming an average residential occupancy of 1.76 persons per home (using 2006 Census data) The water consumption data provided in Table 4 indicates that residential demand accounts for approximately 70% of Bemm River’s annual water consumption.

9 September 2010 11 Bemm River Water Supply Demand Strategy AECOM

4.1.4 Commercial and Industrial Water Use Review of the data provided in Table 4 shows that on average 29% of water is used for commercial and industrial purposes and 71% is used for residential purposes. 4.1.5 High Volume Water Users Review of customer billing data for the 2008/09 financial year (refer to Table 5) shows that there are four customers in Bemm River who account for approximately 40% of the town’s total water use.

Table 5: High Water Users in the Bemm River water supply system Customer Customer Type 2008/09 Water Use (kL) % of Total Demand 1 Agricultural 2,547 15.0% 2 Agricultural 1,655 9.7% 3 Non-Residential 1,228 7.2% 4 Residential 1,150 6.8%

4.1.6 Unaccounted Water Unaccounted water represents the difference between bulk water sourced from the Bemm River and overall water consumption. It includes items such as water lost though leakage due to pipe breaks, process water and any other water not measured. Unaccounted water for the last seven years as determined by EGW is shown in Table 6.

Table 6: Unaccounted Water (EGW, 2009)

02/03 03/04 04/05 05/06 06/07 07/08 08/09 Volume Unaccounted (ML) 16.3 16.8 16.4 17.1 15.3 12.4 0.9 Percentage of Total 48% 47% 49% 50% 46% 49% 5% Volume Diverted (%)

In the previous WSDS (SKM, 2007) it was reported that before commissioning of the WTP there was 10 ML/yr of water used in the disinfection process, this made up approximately 60 - 80% unaccounted water in the Bemm River water supply system up to 2007/08. It was noted and also recommended that the losses in the system be monitored after construction of the new WTP which occurred during 2007. Other unaccounted for water reported was approximately 3.9 ML/yr, around 12% of the volume diverted from the river. From Table 6 it can be seen that the volume of unaccounted water significantly reduced after the construction of the WTP. The volume of unaccounted water during the last financial year (08/09) was 5%. This is lower than the losses across EGW’s entire area of service, which was reported as 8.5% in their 2008/09 Annual Report. This satisfies the target set in EGW’s Water Plan which is to reduce unaccounted water to 10%. Nevertheless EGW should continue to monitor the losses within the water supply system to ensure the last financial year was not an anomaly. 4.1.7 Summary of Current Demand Due to improvements in the treatment process, unaccounted water has been substantially reduced and in 2008/09 diversions were only 19 ML which represents a 45% reduction from the previous long term average of 35.7 ML/annum. As a result of the short period of time post commissioning of the WTP, there is some uncertainty as to whether system losses will remain at this low level over the long term. Therefore a sensitivity analysis of the impact of a future rise in losses has been undertaken in the reliability of supply assessment in Section 7.0 of this report. Table 7 indicates Bemm River’s reduction in monthly diversions as a result of the revised water treatment methods. The figures were determined using the monthly water demand breakdown from the previous DRP (SKM, 2006) (Table 2).

9 September 2010 12 Bemm River Water Supply Demand Strategy AECOM

Table 7: Monthly Water Demand for Financial Year 2008/09 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Total Monthly Demand (ML) 1.18 1.45 1.13 1.30 1.33 1.65 2.14 2.18 2.35 1.80 1.28 0.96 18.76 Unrestrictable Demand (ML) 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 11.51 Restrictable Demand (ML) 0.23 0.49 0.17 0.34 0.38 0.70 1.18 1.22 1.39 0.85 0.32 0.00 7.26

4.2 Forecast Water Demand 4.2.1 Previous Population Projections In the previous WSDS (SKM, 2007), Census data specific to Bemm River was not available for estimating future population. In the absence of this data, population was based on an estimate from Meinhardt (2005a) using 2004 aerial photography and regional census information. The WSDS assumed a 3% increase in population between 2005 and 2055. This increase would see the population rise from 67 people to 69 people over the next 50 years. 4.2.2 Recent Census Data The 2007 WSDS (SKM, 2007) identified the need to review 2006 census data (which was unavailable at the time) to confirm population trends and particularly whether or not the predicted slight increase in population was reasonable. The 2006 Census data has now been released and is compared to SKM (2007) previous assumptions in Table 6. Table 8: Comparison of Previous Population Data with Census Population Data WSDS (SKM, 2007) 2006 Census Population 67 151 Total Dwellings 65 158

The data presented in Table 8 cannot be compared accurately to the 2005 Meinhardt estimate which was based on aerial photography. It also seems unreasonable to have such an increase in population and dwelling numbers over such a short period of time (1 year). It is considered that the Census methodology is more reliable therefore the 2006 figures will be adopted as a basis for future demand forecasting. The 2006 Census data indicates that nearly half the number of dwellings in Bemm River are unoccupied. This suggests there is room for population growth. 4.2.3 Victoria in Future Data The Victoria in Future (VIF) population projections for 2008 suggests an overall increase in population throughout the East Gippsland Region. As Bemm 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 2008 VIF data suggests a 12.4% increase in population for the statistical balance over a period of 20 years (between 2006 and 2026); this is equivalent to a growth rate of approximately 0.6% per annum. This is much higher than the figures reported in the previous release of VIF (2006) which suggested a decrease of 1.5% to 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% p/a). 4.2.4 Proposed Sewerage Scheme Bemm River is about to convert their septic sewer system to a reticulated sewer system and is planned for completion by 2013/2014. Impacts on water consumption when converting between septic sewers and reticulated sewers are difficult to quantify, however the increase on water consumption is not believed to be substantial.

9 September 2010 13 Bemm River Water Supply Demand Strategy AECOM

It is recommended that EGW assess water consumption patterns following completion of the sewerage scheme. This should be completed as part of the regular WSDS revision process. 4.2.5 Summary of future demand The statistical balance is likely to be more appropriate for estimating future population in Bemm River, therefore it is proposed to adopt a growth rate of 0.6% per annum between 2006 and 2026, and a reduced growth rate of 0.4% per annum between 2026 and 2060 (this reduced rate has been estimated based on longer range VIF data). This results in an overall population increase of approximately 45 people. EGSC has advised that there are some small developments being considered however they are not expecting significant growth at Bemm River and an increase of 0.6% p/a initially and 0.4% p/a further in the future would be a reasonable assumption. Adopting this population increase, it is estimated that bulk water extractions will increase to 25 ML/yr over the 50 year planning horizon. It should however be noted that this figure has been calculated based on the demand for the last financial year and not the long term average demand as this has changed dramatically with the significant reduction in losses associated with the commissioning of the new WTP.

9 September 2010 14 Bemm River Water Supply Demand Strategy AECOM

5.0 Demand Management and Reduction

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

5.1.1 Current Demand Reduction Initiatives (SKM, 2007) East Gippsland Water is currently undertaking measures which are expected to result in per capita demand reduction over time. East Gippsland Water is part of the savewater!TM alliance through the Victorian Water Industry Association, which represents all of Victoria’s water corporations. Details of the savewater! TM initiative can be found at http://www.savewater.com.au. The site provides information on water conservation, runs competitions to win water conserving products and provides access to suppliers of water conserving products. For estimating the effect of demand reduction initiatives, East Gippsland Water relies upon the detailed demand information derived from Melbourne’s end-use model, which models property scale demand by considering the in- house and external water use of each property (WaterSmart, 2006a). It is acknowledged that there are some differences between consumer behaviour in Melbourne and East Gippsland, however given the high degree of uncertainty surrounding demand reduction forecasts, this adoption of technical information from Melbourne with justifiable adjustments is considered appropriate. In recent years, water conservation efforts by the water utilities and the Victorian Government have targeted all major aspects of residential water use with an emphasis on education and behaviour change. A rebate scheme for water conservation products has been operating since January 2003. For example, AAA shower roses attract a $10 rebate on the purchase price, whilst rainwater tanks with a connection to the toilet for flushing attract a $300 rebate. The most noteworthy regulatory changes affecting residential indoor water use have been:  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.

9 September 2010 15 Bemm River Water Supply Demand Strategy AECOM

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 Bemm 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.

The above paragraph is written in the context of all of EGW’s supply systems which include coastal towns such as Lakes Entrance. The average daily per capita demand has been estimated based on customer billing data, recent census data and VIF population projections. From this information the average daily water use is 226 L/day per person (based on available data). It is expected that this estimate of demand would vary given that Bemm River is known to have an influx in visitor numbers during peak periods.

Estimating a change in per capita demand is equally problematic without knowledge of changes in seasonally weighted populations. This is because a change in winter population does not necessarily translate directly into a linear change in summer population, which is affected by the state economy (influencing disposable income and therefore travel decisions), weather conditions and accommodation capacity. 5.1.2 Future Demand Reduction Initiatives (SKM, 2007) East Gippsland Water will actively pursue demand reduction in each supply system. East Gippsland Water has set itself a demand reduction target in line with State Government targets set for other water corporations across Victoria of:  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

9 September 2010 16 Bemm River Water Supply Demand Strategy AECOM

 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  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.

9 September 2010 17 Bemm River Water Supply Demand Strategy AECOM

6.0 Water Supply

6.1 Risks and Uncertainties There are a number of factors which may impact on the future reliability of surface water in Bemm River including:  Reduction in the volume of surface water available for extraction due to climate change  Continuation of low flows currently being experienced  Impact of bushfires on the catchment hydrology  Impact of logging on the catchment  Saline water intrusion from sea level rise.

These issues are discussed in the following sections. 6.1.1 Impact of Climate Change The greatest concern for Bemm River’s water supply system relating to climate change is a significant reduction in the volume of surface water available for extraction from the Bemm River. A report titled “Future Runoff Projections (~2030) for South East Australia” by the South Eastern Australian Climate Initiative (SEACI) (2008) was used as the basis for obtaining streamflow reduction figures. The methodology used in this paper is similar to the paper “Rainfall-runoff modelling across the Murray-Darling Basin” (CSIRO 2008), which was used to source streamflow reduction figures for the Omeo WSDS (2010). The key difference between these reports is that the SEACI report uses only a medium emissions scenario to formulate runoff scenarios, while the CSIRO report also considered a high and low scenario. The SEACI report has been adopted for input into the WSDS as it specifically covers the area of Bemm River while the CSIRO report does not. The percentage change in modelled mean annual run off for Bemm River (~2030 relative to 1990) based on SEACI modelling is projected to be -12.2% for the median scenario and -29.9% for the dry scenario. The dry scenario has been selected as the most prudent scenario (i.e. a -29.9% change in mean annual runoff) upon which to plan future water supply as CSIRO have determined that climatic conditions are tracking above previous high climate change scenarios. The previous WSDS (SKM, 2007) stated that: “Based on advice from the Department of Sustainability and Environment (2005), demands are expected to increase by around 1% by the year 2055 for every 6% reduction in streamflow” This would result in an increase in demand (under the dry climate scenario) of approximately 5% by 2055. EGW has a target for an 8% reduction in per capita demand by 2020. It is highly likely that with ongoing demand reduction initiatives, EGW customers will continue to become more efficient with their water use and as a result it’s been assumed that the increase in demand associated with climate change will be offset by more efficient water use. 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.

It is recommended that EGW review these assumptions in 2010 when the additional data is released. In addition to climate change projections modelled in the SEACI report, 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.

9 September 2010 18 Bemm River Water Supply Demand Strategy AECOM

6.1.2 Impacts of Step Change It is possible that the low inflows that have been experienced since 1997 represent a permanent step change. SEACI will be conducting research over the next three years to investigate the reasons for the recent dry conditions and determine the suitability of the various global climate models for south eastern Australia. It may take decades before it is understood if the inflows of the past 12 years are part of the normal cycle of climate variability or if a permanent step change has been experienced. As such, it is important to ensure that water supply planning takes this possibility into consideration. Streamflow gauging on the Bemm River has been relatively consistent since its commencement in 1976. The data in Figure 6 shows that the reduction in streamflow over the last 12 years when compared to the historical record is around 38%.

Figure 6: Bemm River Streamflow Record Given that the step change scenario provides the most severe reduction of streamflow (38%). This scenario has been adopted for further assessment of the water supply system’s reliability. 6.1.3 Impact of Bushfires Bushfires in forested catchments have the potential to significantly impact runoff and therefore streamflows over time. The Bemm River catchment upstream of the town off-take is largely native forest (78%). Previous Bushfires SKM (2007) reported that the most recent bushfire recorded was on 31 January 1983, when 250,000 ha of land was burnt in the Cann River forest district (DSE, 2006), this may have included parts of the Bemm River catchment. Further information on this fire event is not available, however it is expected that a significant proportion of the Bemm River catchment upstream of the town off-take was burnt. The DSE website reported the occurrence of a major fire in the Bemm River area more recently than this on 14 October 1988. This fire burnt 5,670 ha and a perimeter of 80 km. (Fire Protection Branch. Fire Behaviour and Fuel reduction Burning – Bemm River Wildfire October 1988. http://www.dse.vic.gov.au/CA256F310024B628/0/8ED9D891447B33BFCA2574C10035B242/$File/Research+Re port+28-new.pdf)

9 September 2010 19 Bemm River Water Supply Demand Strategy AECOM

Runoff after bushfires initially increases in the first few years until vegetation starts to re-grow, whereupon runoff starts to decrease. The response of catchments to bushfires varies with different vegetation types. This relationship between streamflow and recovery for different species is shown in Figure 7.

Figure 7: Estimated reduction in streamflow due to bushfire (Hill et al, 2008) The curve in Figure 7 suggests the maximum reduction in runoff after a bushfire typically occurs at around 10-20 years after the fire has occurred. Considering that the most recent fire in the region occurred more than 22 years ago it is expected that the full reduction in streamflows due to bushfire is either currently at its peak or have already been experienced. Given that Bemm River has not experienced any supply difficulties in recent years when the effect due to past bushfires would have been greatest, it can be concluded that the past bushfires do not pose a risk to reliability of supply at Bemm River. Discussions with DSE and review of SKM’s bushfire report (2009) have provided an appreciation for the complexity of the interactions between climate change and the impacts associated with bushfires. SKM (2009) stated that: “… the impact of climate change on water resource yield is likely to interact with the expected response following a bushfire such that the two processes may not be independently identifiable. It is not clear how the interaction of the bushfire and climate change impacts on climate change will play out into the future”. DSE has advised that the percentage reductions in streamflow resulting from forest regrowth after a bushfire would be lessened in a drier climate. To account for the lessened impact, a 50% reduction (15% to 7.5% in 2030) in the magnitude of bushfire impacts was modelled when using the high climate change scenario. Future Bushfire The GRSWS (2009) stated that: “The Gippsland Region has been subject to three severe bushfire events in the past decade. Under climate change, it is likely that bushfires will become more frequent, intense and extensive”. While it is likely that the frequency of bushfires will increase into the future, in accordance with advice from DSE, this WSDS has only considered past bushfires as the impacts have been quantified and assessed.

9 September 2010 20 Bemm River Water Supply Demand Strategy AECOM

Proposed Fuel Reduction Burning off within the catchment is considered by DSE to be a necessary measure to ensure that the threat of bushfires is minimised. In accordance with this, it is noted that 5% of the catchment is to be burnt over the next three years. This area is considered to be appropriate provided that a consistent level of burns occur into the future in this catchment. DSE expects runoff impacts from fuel reduction burning to be minor and as a result this has not been considered further in the WSDS. 6.1.4 Forestry Areas within the Bemm River catchment are logged on a rotation basis. Similar to the impacts of bushfires, logging reduces streamflows in the long term as the forests re-establish. From review of available information it appears that logging has been scattered across the water supply catchment with an approximate total area of 30% of the overall catchment logged since 1970. The previous WSDS concluded that the impact of this logging on the off-take would be relatively small, provided the logging remains dispersed across the catchment (SKM, 2007). To ensure reliability of supply it is recommended that EGW continue to monitor the impacts of logging. If a reduction in long term security of supply is anticipated, then a reduction in the area to be logged within the water supply catchment should be sought.

6.2 Future Streamflow Projections The effect of potential climate change on future streamflow is demonstrated in Figure 8.

Figure 8: Future Streamflow Projections Note: Each streamflow projection is plotted exclusive of the impacts of other variables and uncertainties

From Figure 8 it can be seen that the impacts of step climate change has the greatest potential to impact upon streamflow availability in the Bemm River. The step change scenario assumes that the low inflows over the last 12 years are a permanent change.

9 September 2010 21 Bemm River Water Supply Demand Strategy AECOM

7.0 Reliability of Supply

7.1 Current Reliability of Supply Historically the Bemm River has proven to be a reliable supply source. The annual reliability of supply was assessed from daily streamflow data (sourced from the Victorian Data Warehouse) from the Bemm River gauge 221212 at Princes Highway. Analysis of the data over the period 1975 to 2009 indicated that there were no days when flow in the river ceased. The minimum flow on the Bemm River recorded during this period was 30.3 ML/d in 1983, which is well above EGW’s bulk entitlement of 1.47 ML/d. When adjusted for the step change climate scenario, the minimum flow record is estimated to be 18.8 ML/d. This flow is still well above the current bulk entitlement of 1.47 ML/d. Results from this analysis are consistent with the WSDS (SKM, 2007), where a behavioural simulation analysis using REALM was undertaken. The analysis modelled a medium climate change scenario (5% reduction in streamflow) and a continuation of low flows (39% reduction in streamflow in Bemm River). It was concluded that ongoing low flow conditions would not result in a reduction in water supply yield for the town. The system has a total storage capacity of approximately 6.4 ML, which is equivalent to approximately 12 weeks of peak summer demand. 7.1.1 Review of Restriction Triggers The current restriction triggers for Bemm River are shown in Table 9 and are applied when flows drop below specified trigger levels. The trigger levels have been linked to the flow in the Bemm River and the volume within the Bemm River storage.

Table 9: Restriction Triggers for the Bemm River System (SKM, 2006) Flow in Bemm River u/s Volume in Bemm River Stage of Restriction of off-take (ML/d) Storage (ML) 1.47 6.4 Voluntary - 5.0 Stage 2 - 2.5 Stage 4

As reported in the DRP (SKM, 2006), voluntary restrictions shall be introduced when the flow in the Bemm River drops below 1.47 ML/d and streamflows are expected to continue to fall. Mandatory restrictions shall be introduced when the volume in the Bemm River storage starts to fall below 5.0 ML, as shown in Table 9.

7.2 Future Reliability of Supply An assessment was undertaken to determine whether the predicted growth in water demand (see Section 4.2) would have an impact on the system’s reliability of supply. The assessment projected the peak monthly demand at 2060 to be 3.1 ML which can easily be supplied with the existing bulk entitlement on the Bemm River (see Figure 9). It has already been demonstrated (Section 7.1) that low streamflows are not expected to compromise EGW’s ability to utilise its full bulk entitlement during even the driest years. Therefore it is considered that the water restrictions should not be required under a repeat of the past 34 years of hydrology adjusted for the most severe of climate change scenarios. Figure 9 compares current and future bulk water diversions and compares these figures against Bemm River’s maximum bulk entitlement.

9 September 2010 22 Bemm River Water Supply Demand Strategy AECOM

Figure 9: Projected monthly bulk water diversions and corresponding bulk entitlement The future bulk water diversion scenarios were calculated by applying the population growth rate, detailed in Section 4.2.3. The assumption being, that the rate of population will reflect the same increase in volume of bulk water required from the Bemm River. As demonstrated in Figure 9, the increase in bulk water extraction will not impact EGW’s current bulk water entitlements. Further to this Bemm River’s current water supply infrastructure is sized such that it can pump the maximum bulk water entitlement of 1.47 ML/day, while the WTP has a capacity on 0.14ML/day (4.2 ML/month) which is above the projected 2060 peak monthly demand of 3.1ML/day It is therefore concluded that augmentation of the Bemm River water supply system will not be required for the foreseeable future. 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 greater than would be predicted by simply applying the annual reductions across a historical record.

9 September 2010 23 Bemm River Water Supply Demand Strategy AECOM

8.0 Options for Managing Water Supply Long term available supply for the Bemm River water supply system is expected to remain above future demand even after consideration of the most severe of climate change scenarios. As such no major system enhancements are required in regards to water supply reliability. The greater risk to security of supply is the threat of severe bushfires and the associated short term deterioration in water quality following such an event within the catchment. Therefore short term emergency response options are considered below in addition to options for improving management of the system.

8.1 Water Loss Reduction Bemm River has recently had substantial improvements to their water supply system through the commissioning of the WTP in 2007. As a result, losses in the system have reduced substantially from approximately 48% of the total volume diverted to 5%. Data provided in Table 6 demonstrates this reduction and indicates that during the last financial year approximately 0.9 ML (or 4.8% of total water diverted) was lost within the system. While reducing the level of system leakage will not significantly improve water security; EGW should continue to monitor water losses and implement remedial measures when deemed cost effective.

8.2 Demand Management Review of customer billing data for the 2008/09 financial year shows that there are four customers in Bemm River who account for approximately 40% of the town’s total water use. Given that EGW has set itself a target of a 25% reduction in per capita demand by the year 2015 and 30% by the year 2020 relative to the 1990s average usage (SKM, 2007), it is suggested that EGW undertake an audit of these top water users to identify water savings opportunities. As the top water users are a mixture of agricultural, residential and non residential customers, water efficiency initiatives will need to be tailored to each end user.

8.3 Emergency Supply Options Although Bemm River’s previous exposure to bushfires has not been significant, future fire events pose a significant risk to water quality in the Bemm River. This risk is considered manageable through the new WTP and the use of a clear water storage offering 12 weeks of peak summer supply. In the event that an alternative water supply is required, assessments of available options are detailed below. 8.3.1 Water Carting Water carting should only be considered as an emergency supply in the event that Bemm River’s water storage approaches critically low levels or when quality of supply from the Bemm River is compromised (due to bushfires). Water could be carted from one of EGW’s other water supply zones, such as Orbost or Cann River. Cann River would be the closest location to cart from at around 34 km. 8.3.2 Groundwater Groundwater does not currently form part of Bemm River’s water supply system. Groundwater could be used as an emergency supply in the future although this would require construction of a bore. SKM (2006) stated that: “Groundwater could be used as an emergency source of water in all of the towns in this DRP (includes Bemm River, Cann River and Buchan). Lithology is characterised by fractured and weathered indurated sediments, metasediments and intrusives in the vicinity of Buchan (Dept. of Minerals and Energy, 1981). Sands and gravels exist in all other towns in this DRP located closer to the coast.” “Groundwater salinity in the region of Gippsland covered by this DRP (which includes Bemm River) is generally less than 1000 mg/l, which is suitable for drinking. Yields are generally below 10 L/sec.” “The lead time to drill a new groundwater bore is likely to be around one to three months, dependent on the complexity of drilling and design construction. Tasks involve selecting a new site, obtaining internal expenditure approval, obtaining a bore construction licence, obtaining a driller, acquiring bore materials, drilling the bore, pump testing of the bore and water quality testing of the bore”. The past and current reliability of the Bemm River indicates that it is considered unlikely that groundwater will be required as a water supply option.

9 September 2010 24 Bemm River Water Supply Demand Strategy AECOM

Given the unlikely option of alternative supply being required and the capital costs associated with investigation and construction of a new bore, it is recommended that EGW adopt carting as their first preference for alternative water supply. If water security issues arise in the future, EGW should reconsider the need to drill a drought relief bore. It should be noted that the capital costs associated with this are in the vicinity of $75,000.

8.4 Recycled Water Bemm River is currently serviced by septic tanks however options for a reticulated sewerage scheme are currently under consideration. Opportunity for recycled water reuse should be considered as an option if the sewerage scheme is implemented.

8.5 Recommendations for Managing Supply A number of options have been identified to improve the operation of Bemm River’s water supply system. It is recommended that EGW:  Continue to monitor losses within the water supply system  Monitor bulk water extractions to confirm the reduction in losses through the new WTP  Seek to reduce current water demand by auditing high water users and identifying possible savings  In times of emergency, cart water from Cann River or another nearby supply system  Continue to monitor the impacts of logging and if a long term supply shortage is anticipated seek a reduction in the area to be logged within the water supply catchment.

9 September 2010 25 Bemm River Water Supply Demand Strategy AECOM

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.

9 September 2010 26 Bemm River Water Supply Demand Strategy AECOM

10.0 Conclusions and Recommendations

10.1 Conclusion Recent studies and observations have shown that the impacts of climate change have already, and will most probably continue to result in significant reductions in flows in the Bemm River. Annual flow in the Bemm River has been reduced by approximately 38% over the last 12 years when compared to the historical long term average. Analysis of gauged data over the period 1975 to 2009 indicates that the minimum flow record on the Bemm River was 30.3 ML/d during 1983. Adjusted for the most severe climate change scenario, this flow would be estimated at 18.8 ML/d which would still allow EGW to extract their full bulk entitlement of 1.47 ML/d. In addition, the predicted growth in water demand to 2055 (see Section 4.2) can easily be supplied with the existing bulk entitlement on the Bemm River (see Figure 9). It was therefore concluded that EGW will continue to be able to meet their LOS objectives for Bemm River over the next 50 years even considering the impacts of climate change, past bushfires and growth in water demand. As a result, further supply enhancement will not be required.

10.2 Summary of recommendations To further improve system management and performance, it is recommended that EGW action the following strategies for the Bemm River water supply system. Implementing these recommendations in conjunction with those of other the WSDSs will be resource intensive and EGW should prioritise implementation in accordance with the below action plan.

Table 10: Action Plan Action Implementation Update the Bemm River Drought Response Plan Immediate

Monitor bulk water extractions to confirm the reduction in volume through the Ongoing new WTP Continue to monitor the impacts of logging and if long term supply begins to Ongoing diminish, seek a reduction in the area to be logged within the water supply catchment Continue to implement demand reduction strategies Ongoing Undertake a water audit for the high water users 2011

9 September 2010 27 Bemm River Water Supply Demand Strategy AECOM

11.0 References CSIRO, 2008 Rainfall-runoff modelling across the Murray-Darling Basin Department of Conservation Forests and Lands (Land Protection Service) 1986 Proposal for The Proclamation of Bemm River and the Brodribb River (Orbost) Water Supply Catchments May, 1986 Department of Primary Industries (DPI) 2010 A Guide to the Inland Angling Waters of Victoria, http://new.dpi.vic.gov.au/fisheries/recreational-fishing/inland-angling-guide/east-gippsland-21 DSE, 1990 Fire behaviour and fuel reduction burning – Bemm River wildfire October 1988 http://www.dse.vic.gov.au/DSE/nrenfoe.nsf/LinkView/3B0DB7B5948170824A2567E80006BC7976D4DAC795488 C7FCA257603001246B4 DSE, 2005 Guidelines for the Development of a Water Supply Demand Strategy DSE, 2009 Gippsland Region Sustainable Water Strategy – Discussion Paper DSE, 2010 Victorian Water Accounts (2003/04 to 2007/08) A statement of Victorian Water Resources, Melbourne January 2010 http://www.ourwater.vic.gov.au/monitoring/accounts EGCMA, 2006 Protecting and Improving Our River Health: The East Gippsland Regional River Health Strategy 2005 - 2010. East Gippsland Catchment Management Authority, Bairnsdale. Rahmstorf et al, 2007 Recent Climate Observations Compared to Projections. Science 316, 1. SKM, 2006 East Gippsland Water: Drought Response Plan – Orbost, Buchan, Cann River and Bemm River SKM, 2007 East Gippsland Water Supply Demand Strategy Final 04 May 2007 SKM, 2009 Combined impact of the 2003 and 2006/07 bushfires on streamflow – Broadscale Assessment South Eastern Australian Climate Initiative, 2008 Future Runoff Projections (~2030) for South East Australia Southern Rural Water (SRW) 2009 Local Management Rules East Gippsland Basin Catchment September 2009 Victorian Government Gazette 1997 http://gazette.slv.vic.gov.au/view.cgi?year=1997&class=general&page_num=2338&state=V&classNum=G35&sea rchCode=1064675

9 September 2010 28