Orbost Water Supply Demand Strategy

9 September 2010

Orbost Water Supply Demand Strategy AECOM

Orbost 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

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 Orbost Water Supply Demand Strategy AECOM

Quality Information

Document Orbost Water Supply Demand Strategy

Ref 60144336 Task 1.06

Date 9 September 2010

Prepared by Marisa Cesario

Reviewed by Steven Wallner

Revision History

Authorised Revision Revision Date Details Name/Position Signature

A 31-May-2010 Draft for Client Comment Andrew Grant Original Signed Associate Director - Water B 09-Sept-2010 Final Issue for Publication Elisa Hunter

9 September 2010 Orbost Water Supply Demand Strategy AECOM

Table of Contents Executive Summary i 1.0 Introduction 1 1.1 Regional Setting 1 1.1.1 Orbost 1 1.1.2 Marlo 1 1.1.3 Newmerella 1 1.1.4 Jarrahmond 1 1.1.5 Water Supply Catchment 2 2.0 Current Water Supply 3 2.1 Description of Water Supply System 3 2.1.1 Overview 3 2.1.2 Diversion 4 2.1.3 Storage 4 2.1.4 Water Treatment Plant 4 2.1.5 Supply 4 2.2 Allocation of Water 4 2.2.1 Bulk Water Entitlements 4 2.2.2 Licensed Diversions 5 2.2.3 Groundwater Licenses 5 2.3 Level of Service Objectives 5 2.4 Historical Water Restrictions 5 3.0 Previous Studies, Legislation and Regulation 7 3.1 Previous Long Term Planning Studies 7 3.1.1 Drought Response Plan for Bemm River, Buchan, Cann River, Marlo, Newmerella and Orbost (SKM, 2006) 7 3.1.2 EGW Water Supply and Demand Strategy (SKM, 2007) 7 3.2 Regulations and Legislation 7 3.2.1 Surface Water Caps 7 3.2.2 Streamflow Management Plans 7 3.2.3 Groundwater Caps 7 3.2.4 Regional River Health Strategy 8 3.2.5 Heritage Rivers 8 3.2.6 Victorian River Health Strategy 8 3.2.7 Legislation 9 4.0 Water Demand 10 4.1 Current Demand 10 4.1.1 Bulk Water Meter Data and Historical Diversions 10 4.1.2 Demand Profile Estimates 11 4.1.3 Customer Billing Data 12 4.1.4 High Volume Water Users 12 4.1.5 Unaccounted Water 12 4.1.6 Summary of Current Demand 13 4.2 Forecast Water Demand 13 4.2.1 Census Data 13 4.2.2 Victoria in the Future Data 14 4.2.3 East Gippsland Shire Council 14 4.2.4 Summary of Demand Projections 14 5.0 Demand Management 15 5.1.1 Current Demand Reduction Initiatives 15 5.1.2 Future Demand Reduction Initiatives 16 6.0 Water Supply 18 6.1 Risks and Uncertainties 18 6.1.1 Impact of Climate Change 18 6.1.2 Impact of Step Change 19 6.1.3 Impact of Bushfires 19

9 September 2010 Orbost Water Supply Demand Strategy AECOM

6.1.4 Forestry 20 7.0 Reliability of Supply 21 7.1 Current Reliability of Supply 21 7.2 Future Reliability of Supply 21 8.0 Management of Water Supply 23 8.1 Decommissioning the Rocky River Diversion 23 8.2 System Performance Improvements 23 8.2.1 Water Loss Reduction 23 8.3 Demand Management 23 8.4 Emergency Supply Options 24 8.4.1 Water Carting 24 8.4.2 Groundwater 24 8.5 Recycled Water 24 8.6 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 Orbost 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 Orbost water supply system. The Orbost water supply system services the towns of Orbost, Newmerella, Marlo and Jarrahmond. This revised WSDS will replace the strategy set out for the Orbost water supply system in EGW’s overall WSDS (Section 13). 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.

The LOS objectives have been used as a basis for assessing the adequacy of the Orbost water supply system for meeting current and future water demand. 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 streamflows. Streamflow within the Brobribb River alone has been reduced by approximately 48% over the last 12 years when compared to the historical long term average. Results from the assessments undertaken within this report and the previous WSDS (SKM, 2007) indicate that the Brodribb River (the major water source for the Orbost water supply system) is an extremely reliable supply source even with consideration of the most severe of climate change scenarios. Analysis of gauged data over the period 1947 to 2009 indicates that the minimum flow record on the Brodribb River was 17.8 ML/d during 2007. On this day EGW would have been able to extract their full entitlement of 5.74 ML/day. 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 Brodribb River (see Figure 7). The existing diversion on the Rocky River could be decommissioned without any impact to reliability of supply although before doing so, consideration should be given to the other the benefits that the asset provides including its ability to operate as a low energy gravity supply in comparison to the pumped Brodribb River diversion. It was concluded that EGW will continue to be able to meet their LOS objectives for Orbost over the next 50 years even considering the significant impacts of climate change, past bushfires and growth in water demand. As a result, further supply enhancement will not be required. However it is recommended that EGW continue to optimise management of the Orbost water supply system by implementing the actions presented in Table E1.

Table E1: Action Plan Action Implementation Investigate the variability in the volumes of unaccounted water reported Immediate

Update the Orbost Drought Response Plan Immediate

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

Establish district metered areas to investigate the causes behind the variable 2011 levels of unaccounted water and if losses are found to be excessive (i.e. higher than 10%) continue to strive to reduce losses within the water supply system Investigate the costs associated with maintaining the Rocky River diversion to 2011 enable a cost-benefit analysis to be undertaken

9 September 2010 i Orbost 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 now in the process of reviewing these strategies in light of updated climate change, population growth and bushfire information. Continuing dry conditions has 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 the Orbost water supply system recommended that EGW:  reduce uncertainty in the current and future water demand estimates;  continue to pursue additional demand reduction options;  replace ageing infrastructure and obtain legal certainty to entitlements through actions such as the transfer of existing bulk entitlements from the Rocky River to the Brodribb River and the decommissioning of the Rocky River diversion main.

This document forms a revised WSDS for the Orbost water supply system and will replace the strategy set out for Orbost in EGW’s overall WSDS (Chapter 13) prepared by SKM in 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 The Orbost water supply system services a number of towns with the four main ones being Orbost, Newmerella, Marlo and Jarrahmond. A brief description of each town is provided in the following sections of this WSDS with the geographical location of each town shown in Figure 1. 1.1.1 Orbost Orbost is located in the East Gippsland Shire approximately 375 km east of Melbourne and 93 km east of Bairnsdale, where the Princes Highway passes over the Snowy River. Orbost is considered both a coastal and mountain region. Orbost is a medium-sized town with a permanent population of 2,452 (ABS, 2006). It is the service centre for primary industries within the region including beef, dairy cattle, and sawmilling. Orbost is surrounded by national parks, forests, rivers, is close to beaches, and is set on the banks of the Snowy River hence; tourism has become an important industry, with surges in population during major holiday periods. 1.1.2 Marlo Marlo is a small town with a population of around 340 people (ABS, 2010) located at the mouth of the Snowy River, in Victoria's far east, around 14 km south of Orbost. The town is situated on the coast and is often characterised as a seaside resort and fishing town. Marlo has a significant tourist population with a number of holiday houses and caravan parks available for accommodation. 1.1.3 Newmerella Newmerella is a small township located around 5km south-west of Orbost. The 2006 Census reported the population as being 336 (ABS, 2010). 1.1.4 Jarrahmond Jarrahmond is a small township located around 5km to the west of Orbost. The 2006 Census reported the population as being 178 (ABS, 2010).

9 September 2010 1 Orbost Water Supply Demand Strategy AECOM

Figure 1: Locality Plan 1.1.5 Water Supply Catchment The Brodribb River catchment is a sub-catchment of the Snowy River and is responsible for water supply to the Orbost township. The Brodribb River has a total stream length of 72.5 km and has a total catchment area of 1,388 km2 (EGCMA, 2006). A major tributary of the Brodribb River is Cabbage Tree Creek with other smaller tributaries including the Goongerah, Sardine and Martins Creeks (EGCMA, 2006). The Brodribb River floodplain includes Lake Curlip and a number of important ephemeral wetlands (EGCMA, 2006). The Brodribb catchment has extensive areas of forested public land in the upland and midland portions of the catchment. Within the Brodribb River catchment, State Forest management zones and a number of conservation reserves exist. An assessment of the Brodribb catchment in the East Gippsland Regional River Health Strategy (EGCMA, 2006) identified that more than 50% of the Brodribb Catchment is considered to be in good to excellent condition, with 11% assessed in marginal condition. Also noted within the Strategy, was that there is no data available on the condition of more than a third of the catchment.

9 September 2010 2 Orbost Water Supply Demand Strategy AECOM

2.0 Current Water Supply

2.1 Description of Water Supply System 2.1.1 Overview Orbost, as well as Newmerella, Marlo and Jarrahmond (a small satellite settlement) are supplied with surface water from the Brodribb and Rocky Rivers, via a water treatment plant at Orbost. Traditionally the Rocky River has been the primary water supply source, however deterioration of the diversion main has resulted in an increase in water losses and EGW are currently investigating whether it can continue to be a sustainable water source (see Section 8.1 for more details). A schematic of the Orbost supply system is shown in Figure 3. Further details on key components of the system are included in the following sections of this WSDS.

Figure 2: Orbost’s Water Supply System

9 September 2010 3 Orbost Water Supply Demand Strategy AECOM

2.1.2 Diversion Water is pumped from the Brodribb River diversion site at a maximum rate of 5.74 ML/day via an 11 km long rising main which transfers water to the Orbost raw water basin. The Rocky River weir gravity feeds a 21 km long pipeline to the Orbost raw water basin with a maximum flow rate of 1.37 ML/d. 2.1.3 Storage The system has a total storage capacity of approximately 52 ML, consisting of a 45 ML pretreated water dam, 6 ML raw water dam and 0.9 ML storage tank. This is roughly equivalent to four weeks of summer demand peak week assuming no further extraction. To further improve the Orbost water supply system, EGW is currently considering converting the 45 ML dam into raw water storage with the construction of a new clear water storage. Should these proposed changes eventuate, the DRP should be updated accordingly. 2.1.4 Water Treatment Plant The water from the Orbost 6 ML raw water basin is treated at the water treatment plant in Orbost that was built in 1998 and upgraded to increase capacity in 2001. The conventional water treatment plant has capacity to treat 45 L/s (3.9 ML/d). The treatment process employs the coagulation and flocculation process followed by filtration before being disinfected with sodium hypochlorite. The water treatment plant is currently undersized as it is unable to meet peak day demand. When demand is less than the treatment plant’s capacity, surplus treated water is transferred into the 45 ML dam. This is available to augment supply during peak periods. Water in the dam is re-disinfected with chlorine prior to entry into the distribution system. It is understood that EGW are currently investigating the update of the water treatment plant to ensure that it is able to treat peak daily demand as a minimum. 2.1.5 Supply Supply to Orbost and Marlo is by gravity, but is pumped to Newmerella. The nearby community of Jarrahmond is also supplied by gravity from the treatment plant.

2.2 Allocation of Water 2.2.1 Bulk Water Entitlements EGW has an entitlement to extract water from the Brodribb and Rocky River. Conditions of this licence are detailed in the Bulk Water Entitlement (Orbost System) Conversion Order 1997. The annual licensed limit for extraction is 2,031 ML/yr in total from the Brodribb River and Rocky River, and is subject to the following flow sharing arrangements:  When the flow immediately upstream of the Brodribb River pump station is less than or equal to 5.74 ML/day, EGW’s entitlement is equal to the flow from the Brodribb River at the pumping station  When the flow immediately upstream of the Brodribb River pump station is greater than 5.74 ML/day, EGW’s entitlement is equal to 5.74 ML/day from the Brodribb River at the pumping station  When the flow immediately upstream of the Rocky River off-take weir is less than or equal to 1.0 ML/day, EGW’s is not entitled to take any water from the Rocky River  When the flow immediately upstream of the Rocky River off-take weir is greater than 1.0 ML/day but less than or equal to 2.56 ML/day, EGW’s entitlement from Rocky River at the off-take weir is equal to the flow immediately upstream of the Rocky River off-take weir less 1.0 ML/day.  When the flow immediately upstream of the Rocky River off-take weir is greater than 2.56 ML/day, EGW’s entitlement from the Rocky River at the off-take weir is equal to 1.56 ML/day

Further detail on this and the aforementioned flow sharing arrangements and passing flow requirements are outlined in the Victorian Government Gazette (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 2359).

9 September 2010 4 Orbost Water Supply Demand Strategy AECOM

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

Table 1: Number and Volume of Licences issued for the Brodribb River (SRW, 2009) Water Use Number of licences Volume (ML) Direct Pumping 5 360 Domestic and Stock Licences 2 4.4 Bulk Entitlements (EGW) 1 2031 Dairy 1 8.8 Industrial 2 11.2 Total 11 2415.4

From Table 1 it can be seen that the volume of water available to private diverters in the Orbost water supply system is 384.40 ML/year. EGW makes up the remaining licensed volume of 2031 ML/year with their Bulk Entitlement. The local management rules also state the following:  Diversions are metered on the Brodribb River. Customers are not to use more than their licensed volume  Informal rostering of the Brodribb River can occur when streamflow reduces to 8 ML/d upstream of the town off-take, though this has not known to have occurred. There are currently only two active users on the Brodribb River. 2.2.3 Groundwater Licenses Groundwater is not currently used as part of the Orbost water supply system, as a result no groundwater licences are held.

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 All towns supplied by the Orbost water supply system are currently subject to Permanent Water Saving Rules (PWSR), which are being applied as part of a Victoria wide strategy.

2.4 Historical Water Restrictions The following provides a brief summary of Orbost’s historical water restrictions as reported in the previous DRP (SKM, 2006).  It was reported in the Snowy River Mail that restrictions were imposed in Orbost in January 1973. During this time flow in the Rocky River at the diversion weir ceased and pumping from the Brodribb River had been reduced to around four hours per night. Restrictions were lifted on 7/2/73, even though the drought had not yet broken and was reported by SKM (2006) that it possibly indicated that restrictions were prematurely imposed  The Snowy River Mail (1982/83) announced that flows in the 1982 drought were sufficient in the Rocky River to meet all demands. At the time the town relied on both the Rocky River and the Brodribb River for its supply, with the diversion operating at 60% of pipeline capacity. Hence, there were no restrictions imposed on Orbost in 1982/83

9 September 2010 5 Orbost Water Supply Demand Strategy AECOM

 In the 1997/98 drought, pumping from the Brodribb River increased from 4 hr/d to as much as 15.5 hr/d. Both the Rocky and Brodribb Rivers continued to flow throughout the drought. Flows at Rocky River reduced to run over only 50% of the weir in early March 1998. The lowest levels reached in the Brodribb River were 2.49 m below the top of the inlet structure. In 1983 the Rocky River diversion reduced to 30% of the pipeline operating capacity; although restrictions were not imposed.

Since the 1973 drought, voluntary restrictions have only been implemented in Orbost on one other occasion during January 2003. According to an EGW Media Notice (14 May 2003), the voluntary restrictions were implemented due to low inflows over the summer period and were lifted in May 2003 following rain.

9 September 2010 6 Orbost 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 Bemm River, Buchan, Cann River, Marlo, Newmerella and Orbost, SKM (2006)  Water Supply Demand Strategy, SKM (2007)

These 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 authorities holding a retail water license are required to develop a Drought Response Plan (DRP) for approval by the Minister. The DRP for Orbost 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 Orbost’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 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. The Brodribb River is located within the Snowy River Basin. This Basin was fully capped and allocated in 2004 (prior to the release of the Victorian Government White Paper 2005). As a result, 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). 3.2.2 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. There is currently no SFMP that applies to the Brodribb or Rocky Rivers. 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  Unincorporated Area (UA) – these cover aquifers where groundwater is expected to provide little potential due to low yields or poor water quality.

9 September 2010 7 Orbost Water Supply Demand Strategy AECOM

Orbost

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

(Source http://gmu.geomatic.com.au/Default.aspx) The Snowy River Basin includes the entire Orbost GMA. Groundwater is not used as an urban supply in the Snowy Basin (DSE, 2010) and EGW does not hold a groundwater extraction licence. The Orbost GMA has a PAV of 1,201 ML/yr and is only accessible by trade, as the licensed entitlement has reached the PAV (DSE, 2009). 3.2.4 Regional River Health Strategy Stream value for the Brodribb River, 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 EGCMA has identified management units for the Brodribb River Catchment, which includes the Brodribb River estuary and floodplain, the Brodribb River upland, and Cabbage Tree Creek. Three of the eight reaches in the Planning Unit have been identified as High Value Streams (EGCMA, 2006). 3.2.5 Heritage Rivers The Heritage Rivers Act (HRA) 1992 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 Brodribb River (and Rocky River) does not fall under the Heritage River classification and therefore is not subject to any of the above limitations under the HRA. 3.2.6 Victorian River Health Strategy The Victorian River Health Strategy 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).

9 September 2010 8 Orbost Water Supply Demand Strategy AECOM

The Brodribb River and Rocky River are unregulated rivers (i.e. streamflows that are not controlled by major dams or weirs) and are subject to those policies set out within the VRHS. 3.2.7 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 Orbost Water Supply Demand Strategy AECOM

4.0 Water Demand This chapter of the report discusses the current water demands on the Brodribb River and Rocky 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. Orbost has not been subject to water restrictions in recent years 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 Bulk Water Meter Data and Historical Diversions Table 2 presents the past seven years of statistics on bulk water diverted from the Brodribb River and Rocky River and the total water consumption as published in EGW’s annual reports.

Table 2: Bulk Water Meter Data (Source: EGW’s annual reporting of water consumption statistics)

02/03 FY 03/04 FY 04/05 FY 05/06 FY 06/07 FY 07/08 FY 08/09 FY Bulk water diverted from 961.9 771.9 851.3 868.2 1032.5 773.9 780.2 steams Total water 715.8 721.9 693.1 625.3 751.0 652.0 752.7 consumption 1 1 Includes both residential and non residential demand

A significant difference between the volume of bulk water diverted and that consumed occurred in 06/07 financial year. This can be attributed to the Alpine bushfires within the region that occurred during that year, where more water was used for fire fighting and fire suppression activities. The same conclusion could also be drawn for the peak in bulk water diverted in the 02/03 period for the 2003 bushfires. The historical annual bulk water diversions at Orbost dating from 96/97 to 08/09 and annual water consumption have been presented in Figure 4. This data was sourced from the previous DRP (SKM, 2006) and EGW annual reporting. It should be noted that the values between 1996 and 2002 have been inferred from a graph produced in the previous DRP (SKM, 2006) and as such are indicative only.

9 September 2010 10 Orbost Water Supply Demand Strategy AECOM

Figure 4: Historical annual bulk water diverted and consumed in Orbost

Figure 4 shows a steady increase in bulk water extractions from 1996 to 2000 after which time growth in extractions and consumption has plateaued (excluding two extreme years related to bushfire events). This trend is consistent with other water systems operated by EGW. The average annual bulk water diversion volume over the past 5 years (excluding bushfire years) was calculated as 810 ML/yr while the average annual demand over the same period was 689 ML/yr. 4.1.2 Demand Profile Estimates Analysis of recent bulk water meter data (06/07, 07/08 and 08/09) confirmed the monthly water consumption profile presented in the previous DRP (SKM, 2006). The current seasonal, restrictable and unrestrictable demands are presented in Table 3. The unrestrictable demand has been determined based upon the assumption made in the previous DRP (SKM, 2006) that unrestrictable demand is equivalent to 85% of the average demand of the three months of the lowest water use (i.e. August, September and October). Table 3: Monthly Water Demand (adapted from SKM 2006)

Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Total Monthly Demand (ML) 57 21 27 27 90 114 106 92 87 73 61 54 810 Percentage of Annual 7 3 3 3 11 14 13 11 11 9 8 7 100 Demand (%) Unrestrictable Demand 21 21 21 21 21 21 21 21 21 21 21 21 256 (ML) 1 Restrictable Demand 36 0 6 6 69 93 85 71 66 51 40 33 554 (ML) 1 1 Figures have been rounded therefore may not add up to total monthly demand

9 September 2010 11 Orbost Water Supply Demand Strategy AECOM

4.1.3 Customer Billing Data EGW has provided customer billing data for the Orbost water supply system to assist with evaluating water use within the supply area. A summary of data provided by EGW is shown in Table 4.

Table 4: Customer Billing Data (Source: EGW’s annual reporting of water consumption statistics)

06/07 07/08 08/09 Residential connections unknown 1541 1560 Non-residential connections unknown 374 376 Total connections 1937.0 1915 1936 Residential water use (ML) 316.6 255.7 302.2 Non-residential water (ML) 434.4 396.4 450.5 Total water use (ML) 751.0 652.1 752.7

The customer billing data provided in Table 4 indicates that residential demand accounts for approximately 40% of Orbost’s annual water consumption. As described in the previous DRP (SKM, 2006) non-residential water demand consists of “dairy and cattle farms in Brodribb, Jarrahmond and Lochend that are connected to the urban reticulation system at Orbost. Water is used for hosing down dairies and washing stock. Dairy farmers represent around 10% of the total number of customers in the Orbost System, but account for approximately 30% of water use. Several timber mills are also connected to the Orbost urban system”. 4.1.4 High Volume Water Users Review of customer billing data for the 08/09 financial year shows that the top ten water users (defined as those customers using more than 5 ML/yr) account for approximately 94,719 ML (or 19%) of the total water consumed in that year. Table 5 shows the high water users within Orbost’s water supply system.

Table 5: High Water Users in the Orbost water supply system Customer Customer Type Water Use (ML) % of Total Demand 1 Non-Residential 14.02 2.77% 2 Non-Residential 12.57 2.48% 3 Non-Residential 12.20 2.41% 4 Non-Residential 10.36 2.04% 5 Non-Residential 10.01 1.98% 6 Non-Residential 8.40 1.66% 7 Residential 7.42 1.46% 8 Non-Residential 6.80 1.34% 9 Non-Residential 6.58 1.30% 10 Non-Residential 6.37 1.26%

A review of the list of top ten water users identified that 1.5% of water is used by residential customers whilst the remaining 17.5% is used for non-residential purposes. Orbost has been identified as one of the major service centres for primary industries within the region including beef, dairy cattle, and sawmilling and the top 10 list reflects this. 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). This information can assist in expanding EGW’s demand reduction program for larger water users by working with the top ten customers within the Orbost water supply network in identifying water leakage and water use efficiency. 4.1.5 Unaccounted Water Unaccounted water was calculated as the difference between the bulk water sourced from the Brodribb and Rocky Rivers and the overall water consumption in addition to any accounted water not billed by EGW. It includes items such as water lost though leakage, process water, pipe breaks and any other water not calculated. Unaccounted water for the last seven years as determined by EGW is shown in Table 6.

9 September 2010 12 Orbost Water Supply Demand Strategy AECOM

Table 6: Usage summary for unaccounted water

02/03 03/04 04/05 05/06 06/07 07/08 08/09 Volume Unaccounted 246.1 42.7 134.9 222.0 252.7 104.2 15.0 (ML) Percentage of Total Volume 26% 6% 16% 26% 24% 13% 2% Diverted Source: EGW’s annual reporting of Water Consumption Statistics by system.

The data provided by EGW shows that unaccounted water over the last seven years is highly variable. It is possible that the bushfires in 03/04 and in 06/07 contribute to this variability. However the unaccounted water in 08/09 (approximately 2% of the total volume diverted) is considered extremely low for an urban water supply system. Losses across EGW’s entire area of service were reported as 8.5% in their 08/09 Annual Report. The target set in EGW’s Water Plan is to reduce unaccounted water to 10% (averaged across all water supply systems). Given the strong historical variability in unaccounted water within the Orbost water supply system, it is recommended that EGW undertake further investigation and interpretation of data to establish accurate trends. If it is found that unaccounted water is currently higher than 10%, then it is further recommended that EGW implement additional measures to reduce losses within the Orbost water supply system. 4.1.6 Summary of Current Demand An average annual bulk water diversion of 810 ML/yr has been calculated based upon the last 5 years of data, excluding the bushfire years in 06/07.

4.2 Forecast Water Demand To predict future water demand in Orbost, Marlo, Newmerella and Jarrahmond, the likely trends in population have been reviewed and summarised in the following sections. 4.2.1 Census Data Orbost The population of Orbost between 1981 and 1991 was stable however the following period saw a rapid decrease from 2,515 people in 1991 to 2,150 people in 1996 (SKM 2007). According to the Australian Bureau of Statistics (ABS), the 2001 census recorded a population of 2,085 within Orbost’s urban centre, this population increased to 2,097 during 2006 giving an increase of 0.1% per annum. It should be noted that the urban centre boundaries between the 2001 and 2006 census slightly increased distorting the true population growth between the census years. East Gippsland Shire Council (EGSC) confirmed that the difference in population counted in 2001 and 2006 was due to the change in the boundary, which added approximately 40 people (EGSC, 2008). Marlo The population at Marlo has fluctuated between 300 and 400 people over the past two decades. Census data is only available for 2001 and 2006, with a population of 339 and 340 recorded respectively; this is equivalent to an increase of 0.2% per annum over the period. Newmerella and Jarrahmond With only 2006 Census data available for both Newmerella and Jarrahmond there is no estimate of the annual population increase. The 2006 population counts for Newmerella and Jarrahmond are 336 and 178 people respectively. A summary of the ABS population statistics for the four towns have been presented in Table 7.

9 September 2010 13 Orbost Water Supply Demand Strategy AECOM

Table 7: Summary of Census Statistics (Source: ABS, 2010)

Population Total Dwellings Occupied Dwellings Orbost 1996 2150 2001 2085 1032 902 2006 2097 1037 888 Marlo 2001 339 268 150 2006 340 273 153 Newmerella 2006 336 152 134 Jarrahmond 2006 178 74 63 4.2.2 Victoria in the Future Data The Victoria in Future (VIF) population projections for 2008 suggest an overall increase in population throughout the East Gippsland Region. Given that Orbost has been identified as an urban centre, dedicated population projections for the 20 years following 2006 have been made. The 2008 VIF data indicates a 10.1% increase in population for Orbost over a period of 20 years (between 2006 and 2026); this is equivalent to a growth rate of approximately 0.48% per annum. For the following 30 years (between 2026 and 2056) the projected growth for Orbost has also been applied providing an equivalent growth rate of approximately 0.32% per annum. These growth rates have been selected as they provide a specific growth rate for the region, and as a result are more likely to provide a realistic forecast when compared to the wider projections for regional Victoria. 4.2.3 East Gippsland Shire Council The EGSC does not have a specific population forecast for Orbost although it does predict a 1.4% increase in population across the entire Shire. This prediction is based on 2006 Census data. Under Council’s Coastal Design Framework Project, a report on The Urban Design Framework (UDF) for Marlo was prepared. This UDF was submitted during 2007 and with regards to population, it states that the average annual growth rate over fifteen years to 2001 in Marlo was 0.7%, which was the same for the Shire of East Gippsland. The report also concludes that if this growth rate was to be maintained, the population would reach 400 persons by 2031. It is further stated that the peak summer population at Marlo would swell to 800 to 1000 people. 4.2.4 Summary of Demand Projections To estimate future demand, the VIF growth rate of 0.48% per annum between 2006 and 2026 was used for all towns within the Orbost water supply system. Beyond 2026 the population is expected to increase according to the lower rate of 0.32% per annum. Adopting these increases, it is estimated that bulk water extractions will increase to 976 ML/yr over the 50 year planning horizon.

9 September 2010 14 Orbost Water Supply Demand Strategy AECOM

5.0 Demand Management 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 EGW 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 authorities. 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, EGW 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 EGW 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, EGW 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 and Eagle Point. These are areas where East Gippsland Water believes that high rates of leakage may occur.

9 September 2010 15 Orbost 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. 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. 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 EGW will actively pursue demand reduction in each supply system. EGW has set itself a demand reduction target in line with State Government targets set for other water authorities 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, EGW 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  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

9 September 2010 16 Orbost Water Supply Demand Strategy AECOM

 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 EGW’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 Orbost 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 Orbost 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.

These issues are discussed in the following sections. 6.1.1 Impact of Climate Change The greatest concern for Orbost’s water supply system relating to climate change is a significant reduction in the volume of surface water available for extraction from the Brodribb and Rocky Rivers. Two reports which formulate streamflow reduction due to the impacts of climate change are, Future Runoff Projections (~2030) for South East Australia, by the South Eastern Australian Climate Initiative (SEACI, 2008) and Rainfall-runoff modelling across the Murray-Darling Basin, by CSIRO (2008). 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.” Neither of the study areas of the CSIRO or SEACI reports include Orbost, however in order to provide an approximation of the impact of climate change to the Brodribb and Rocky Rivers the SEACI data was adopted as the study boundaries are much closer to the water supply sources when compared to the boundaries used in the CSIRO report. Using the closest co-ordinates available from the SEACI data to the Brodribb and Ricky Rivers, the percentage change in modelled mean annual runoff for Orbost (~2030 relative to 1990) is projected to be -5.1% for the median scenario and -9.8% for the dry scenario. In addition to the climate change projections modelled for streamflow 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. With regards to the impacts on climate change on demand 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 1.6 % (or 12 ML/annum based upon total water used in 2008/09, see Table 4) 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.

9 September 2010 18 Orbost Water Supply Demand Strategy AECOM

6.1.2 Impact of Step Change It is possible that the low flows 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 Brodribb River has been relatively continuous since 1947. When comparing the last 12 years of streamflow data to the historical record (refer to Figure 5) it can be seen that there has been a reduction of approximately 48% in annual streamflow. The Rocky River was not included in this analysis as available gauge data available did not include the last 12 years.

Step Change 48% Reduction in Streamflow

Figure 5: Brodribb River Annual Streamflow

Given that the step change climate change scenario provides the most severe reduction in streamflow of around 48%, this scenario will be the 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. 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.

9 September 2010 19 Orbost Water Supply Demand Strategy AECOM

The Orbost catchment is predominately native forest with mixed species of eucalypt trees, the most common being E.Sieberi or Silvertop. 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 6.

Figure 6: Estimated reduction in streamflow due to bushfire (SKM, 2009) Previous Bushfire Events The Brodribb River catchment was not been affected by the 2003 fires nor the more recent 06/07 fires. Furthermore, there has been no major bushfires recorded over the last few decades. It can therefore be concluded that previous bushfires are currently not impacting upon streamflows within the Brodribb River catchment. 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 17% of the catchment is to be burnt over the next three years. 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 water quality. 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 Orbost catchment are logged on a rotation basis. Similar to the impacts of bushfires, logging reduces streamflows in the long term as the forests re-establish. From review of available information it seems that logging has been scattered across the water supply catchment with a total area of around 20% 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 was dispersed across the catchment (SKM, 2007). To ensure reliability of supply it is recommended that EGW continue to monitor the impacts of logging and if long term supply begins to diminish, seek a reduction in the area to be logged within the water supply catchment.

9 September 2010 20 Orbost Water Supply Demand Strategy AECOM

7.0 Reliability of Supply

7.1 Current Reliability of Supply Historically the Brodribb River has proven to be a reliable water supply source, however despite receiving close to average rainfall in recent years, streamflows across the Snowy catchment are well below average due to the ongoing effect of previous dry years having depleted soil moisture. This is evident when observing streamflow at the Brodribb River which was only 26% in 2003/04 and 36% of the long term average in 2004-05 (National Water Commission, 2005). The system has a total storage capacity of approximately 52 ML, consisting of a 45 ML clear water dam, 6 ML raw water dam and 0.9 ML storage tank which is equivalent to approximately 3 weeks of summer demand. The annual reliability of supply was assessed from daily streamflow data (sourced from the Victorian Data Warehouse) from the Brodribb River gauge at Sardine Creek. Analysis of the data over the period 1947 to 2009 indicates that the minimum flow recorded on the Brodribb River was 17.8 ML/d during 2007. By adjusting the data set for the step change climate scenario, the minimum flow record for the Brodribb River becomes 9.7 ML/d (based on 1983 hydrology). This minimum flow is above both the trigger level for voluntary restrictions (8 ML/d) and the limit on EGW’s current bulk entitlement beyond which extraction rates are restricted (5.74 ML/d). This indicates that the Brodribb River is currently an extremely reliable supply even in consideration of the most severe of climate change scenarios. The same analysis was undertaken for the Rocky River based on available data from 1973 to 1977. Flow in the Rocky River is less reliable and zero flows occurred regularly over the period of available data. As there was no data available over the last 12 years for the Rocky River, an assessment of the current reliability was not undertaken. Results from this analysis are consistent with the previous WSDS (SKM, 2007), where a behavioural simulation analysis using REALM was undertaken. The analysis modelled a medium climate change scenario (11% reduction in streamflow) and a continuation of low flows (40% reduction in streamflow in Brodribb River and 22% reduction in Rocky River). It was concluded that only a slight reduction in yield would occur, which would be insufficient to result in any impact on the level of service over the planning horizon.

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 2055 to be 135 ML which can easily be supplied with the existing bulk entitlement on the Brodribb River (see Figure 7). 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 50 (1947-2007) years of hydrology adjusted for the most severe of climate change scenarios. Given that the Brodribb River has sufficient reliability to meet the Orbost system’s supply needs, EGW could elect to decommission the Rocky River off-take if it desires to do so.

9 September 2010 21 Orbost Water Supply Demand Strategy AECOM

Figure 7: Projected monthly bulk water diversions and corresponding bulk entitlement limits

The future bulk water diversion scenarios were calculated by applying the population growth rate, detailed in Section 4.2.4. The assumption being, that the rate of change in population will reflect the same increase to the necessary volume of bulk water required from the Brodribb River. As demonstrated in Figure 7, the increase in bulk water extraction will not impact EGW’s current bulk water entitlements even when excluding the Rocky River licence over the current planning horizon. While current climate change projections are based on a reduction in annual streamflow, seasonal variations in streamflow are yet to be assessed in detail due to a lack of available research. 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 22 Orbost Water Supply Demand Strategy AECOM

8.0 Management of Water Supply Available supply is expected to exceed future demands even after consideration of the most severe of climate change scenarios. Although Orbost’s water supply system does not require any major enhancements, the following options could be considered to improve management of the system.

8.1 Decommissioning the Rocky River Diversion As reported in the previous WSDS (SKM, 2007 p. 121) the Rocky River diversion main is nearing the end of its design life and will have an increased prevalence for leaking and bursting, EGW estimate that it has a remaining useful life of 5-10 years. Previous recommendations identified that rather than replacing this main, an alternative would be to pump more water from the Brodribb River at its current location or to divert water by gravity from an alternative location. EGW previously examined this issue and considered that it was part of the design intent of the Brodribb River supply, that EGW would eventually decommission the Rocky River diversion at the end of its useful life in favour of a single supply source (SKM, 2007). The analysis performed in Section 7.1 and 7.2 confirmed that the Brodribb River diversion provides sufficient reliability of supply for the long term future without the use of the Rocky River diversion. However, the Rocky River does have some benefits that require consideration prior to any decision to decommission the infrastructure:  The Rocky River diversion enables supply by gravity whereas the Brodribb River requires pumping. Any supply sourced from the Rocky River will therefore minimise energy use and associated production of greenhouse gasses  The Rocky River diversion main provides supply to a number of ‘supply by agreement’ customers. EGW is currently investigating opportunities to transfer customers from the Rocky River diversion main to the Brodribb River diversion main  Two diversions provides for greater operational flexibility if there is a disruption in supply from either source.

It is recommended that EGW further investigate the costs associated with maintaining or replacing the Rocky River diversion, to allow a cost benefit analysis to be undertaken. This analysis should consider whether or not the main should be retained in the event that carbon prices significantly increase in the future. The following sections of this report outline a number of potential options for securing water supply in times of extreme drought, bushfire events or other emergencies.

8.2 System Performance Improvements 8.2.1 Water Loss Reduction Data provided in Table 6 indicates that over the last seven years there has been significant variation in the unaccounted for water reported. It is recommended that EGW undertake further investigation and interpretation of data to establish accurate trends. If it is found that unaccounted water is currently higher than 10%, then it is further recommended that EGW implement additional measures to reduce losses within the Orbost water supply system. While reducing the level of leakage will not significantly improve water security, it will reduce system operating costs.

8.3 Demand Management There are ten customers in Orbost, accounting for approximately 20% of demand (95,000 ML/year). A review of the list of top tem water users identified that 1.5% of water is used by residential customers whilst the remaining 17.5% is used for non-residential purposes. 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), opportunities for water savings amongst these customers should be investigated. Savings that can be made include the installation of water efficient devices such as shower heads, potable substitution with rainwater or other water sources, leakage detection and education awareness programs.

9 September 2010 23 Orbost Water Supply Demand Strategy AECOM

It is difficult to quantify the savings associated with reducing demand from the top water users and as such it is recommended that EGW undertake a demand analysis and audit top water users to determine the feasibility of these water savings.

8.4 Emergency Supply Options While historical data shows that the Orbost water supply system is highly reliable in terms of its resilience to drought, the water supply can still be vulnerable to water quality related issues due to impacts such as bushfire. To ensure that options are available in the event of an emergency whereby water supply from the Brodribb and/or Rocky Rivers is not available, a number of options have been identified. These are detailed as follows. 8.4.1 Water Carting Water carting should only be considered as an emergency supply in the event that Orbost’s water storage approaches critically low levels or when quality of supply from the Brodribb River is compromised (due to bushfires). Water could be carted from one of EGW’s other water supply zones such as Nowa Nowa, Bemm River or Buchan. Nowa Nowa would be the closest location to cart from at around 37 km. 8.4.2 Groundwater Groundwater does not currently form part of Orbost’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”. The lithology at Orbost is likely to be characterised by sand and gravel. “Groundwater salinity in the region of Gippsland covered by this DRP (which includes Orbost) 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 Brodribb River indicates that it is considered unlikely that groundwater will be required as a water supply option. Further to this, the extensive groundwater development means access will be fairly complex and as such would only be considered in emergency situations. Given the low likelihood 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.

8.5 Recycled Water EGW already recycles 100% of effluent passed through the Orbost wastewater treatment plant. The water is recycled and reused for a number of agricultural applications, including pasture and tree plantations. Given that recycled water is fully committed there is little opportunity to further use this water for additional potable substitution. A summary of the last five years of recycled water use in Orbost as reported in the Victorian State Water Accounts is presented in Table 8.

Table 8: Volume of recycled water sourced from the Orbost wastewater treatment plant (DSE, 2010) Victorian Water Account Reporting Period Total volume of effluent (ML) 2007/08 268 2006/07 198 2005/06 276 2004/05 217 2003/04 323

9 September 2010 24 Orbost Water Supply Demand Strategy AECOM

8.6 Recommendations for Managing Supply A number of options have been identified to improve the security of Orbost’s water supply system. It is recommended that EGW:  Establishment of district metered areas to investigate the causes behind the variable levels of unaccounted water and if losses are found to be excessive (i.e. higher than 10%) continue to strive to reduce losses within the water supply system  In times of emergency, cart water from Nowa Nowa, Bemm River or Buchan  Continue to implement demand reduction strategies to assist in achieving EGW’s demand reduction targets (8.5% reduction in per capita demand by 2020)  Update Orbost’s Drought Response Plan.

9 September 2010 25 Orbost Water Supply Demand Strategy AECOM

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

9 September 2010 26 Orbost 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 streamflows. Streamflow within the Brobribb River alone has been reduced by approximately 48% over the last 12 years when compared to the historical long term average. Results from the assessments undertaken within this report and the previous WSDS (SKM, 2007) indicate that the Brodribb River (the major water source for the Orbost water supply system) is an extremely reliable supply source even with consideration of the most severe of climate change scenarios. Analysis of gauged data over the period 1947 to 2009 indicates that the minimum flow record on the Brodribb River was 17.8 ML/d during 2007. On this day EGW would have been able to extract their full entitlement of 5.74 ML/day. 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 Brodribb River (see Figure 7). The existing diversion on the Rocky River could be decommissioned without any impact to reliability of supply if the planned leakage assessment on the diversion main determines that the source is no longer viable. It was concluded that EGW will continue to be able to meet their LOS objectives for Orbost over the next 50 years even considering the significant impacts of climate change, past bushfires and growth in water demand. As a result, further supply enhancement will not be required.

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

Table 9: Action Plan Action Implementation Investigate the variability in the volumes of unaccounted water reported Immediate

Update the Orbost Drought Response Plan Immediate

Establish district metered areas to investigate the causes behind the variable 2011 levels of unaccounted water and if losses are found to be excessive (i.e. higher than 10%) continue to strive to reduce losses within the water supply system Investigate the costs associated with retaining the Rocky River diversion to 2011 enable a cost-benefit analysis to be undertaken

9 September 2010 27 Orbost Water Supply Demand Strategy AECOM

11.0 References 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 East Gippsland Shire Council 2008 Confirmation of Census Collection District Boundaries Bruce Smith, Social Planner [email protected] (emailed 13/5/2010) EGCMA 2006 Protecting and Improving Our River Health: The East Gippsland Regional River Health Strategy 2005 - 2010. East Gippsland Catchment Management Authority, Bairnsdale. Meinhardt Infrastructure & Environment Pty Ltd 2007 Marlo Urban Design Framework Volume 3. March 2007 Prepared for East Gippsland Shire, Wellington Shire and the Victorian Department of Sustainability and Environment t National Water Commission 2005 Australian Water Resources 2005 Regional Water Resource Assessment Inter- jurisdictional Area- Snowy River -Water Resource Australian Government (last updated 5/6/2007) http://www.water.gov.au/RegionalWaterResourcesAssessments/SpecificGeographicRegion/TabbedReports.aspx ?PID=NSW_SW_222x (accessed 29/04/2010) 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 Supply Demand Strategy Final 04 May 2007 SKM 2009 Combined impact of the 2003 and 2006/07 bushfires on streamflow - Broadscale Assessment Southern Rural Water (SRW) 2009 Local Management Rules Snowy River Catchment September 2009 The State of Victoria Department of Sustainability and Environment (DSE) 2009 Gippsland Region Sustainable Water Strategy Discussion Paper, Melbourne July 2009 The State of Victoria Department of Sustainability and Environment (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 (accessed 25/05/2010)

9 September 2010 28