Gellibrand River Summer Flows Improvement

Assessment of options

Dated July 2019

Gellibrand River Summer Flows Improvement: Assessment of Options

Report Name: Gellibrand Summer Flows Improvement: Assessment of Options Report Custodian: Tim Harrold Checked by: Jackie Bowe, Peter Wilson, Ian Bail, Kellie King Approved by: Peter Wilson Date: July 2019 Version No: 4

Document Control Revision Date Author(s) Brief Description of Change No 1 Oct 2018 Tim Harrold Original, for review at Project Control Group Meeting 2 Feb 2019 Tim Harrold After PCG and WW executive review

3 May 2019 Tim Harrold After second review (tracked changes are from rev 2)

4 July 2019 Tim Harrold For public release

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Gellibrand River Summer Flows Improvement: Assessment of Options

Contents Executive summary ...... 5 1. Introduction ...... 8 1.1 Previous studies ...... 8 1.2 Work since May 2016 ...... 8 2. Community Engagement ...... 9 2.1 Definition of community engagement...... 9 2.2 Scope and context of the community engagement ...... 9 2.3 Design and delivery of engagement activities ...... 9 2.4 Who was engaged ...... 10 2.5 Engagement activities and outcomes ...... 10 3. Options for improving summer flows ...... 11 3.1 Business as usual - Current practices contributing to improved summer flows ...... 11 3.2 Possible operational Interventions ...... 12 3.3 Possible engineered options ...... 13 3.4 Discussion of Environmental Benefits...... 18 4. Discussion ...... 19 5. References ...... 20 Appendix A: WRSWS Action 7.3: Progress Report ...... 21 Appendix B: Outcomes from the South Otway groundwater investigation November 2017...... 22 Appendix C: Community Engagement ...... 24 Definition of community engagement ...... 24 Scope and context of the community engagement ...... 24 Design and delivery of engagement activities ...... 24 Who was engaged ...... 24 Summary of engagement activities and outcomes ...... 25 Appendix D: New options November 2017 ...... 29 Appendix E: Water quality issues ...... 31 Appendix F: Assumptions about the options ...... 32 Number of days per year that flow substitution is required ...... 32 The Otway System BE and Option NW ...... 34 Appendix G: Environmental Flow Benefits ...... 35 Appendix H: “Doing our bit to help the Gellibrand River” ...... 37

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Gellibrand River Summer Flows Improvement: Assessment of Options

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Executive summary

The Gellibrand River is under ecological stress during summer low flow periods, and this stress could be reduced if Wannon Water reduced its extractions from the river at these times. A number of options to improve the summer flows in the Gellibrand River were identified with input from the Wannon Water infrastructure planning and operational teams, a multi-agency Project Control Group and a Stakeholder Reference Group. Detailed investigations were carried out for some of the options. The option are either business as usual, operational interventions or engineered options. Business as usual - Current practices contributing to improved summer flows  Ongoing improvements in water use efficiency including leak detection, partnerships with industry and community education;  Expansion of centralised roof water harvesting in Warrnambool for an anticipated 3000 new houses, and a new industrial estate over the next 30 years;  Promotion of integrated water management, including identification of alternative local sources such as local ground water, storm water and recycled water;  Cessation of pumping (subject to operational considerations) during artificial estuary openings. Possible operational interventions  Voluntary water efficiency campaign to reduce the summer use of Otway System customers;  Summer vs winter pricing - water price could be higher in summer than in winter, with the aim of increased awareness, and reduced summer demand. This is a complex issue and would need to be considered as part of Wannon Water’s broader pricing arrangements.  Airspace option - draw down existing system storage more over summer. This is also a complex issue for Wannon Water that will be examined in detail in a 2019 project;

Possible engineered options A number of engineered options were investigated. Most of these options involve providing water from an alternative water source for customers over the summer period so that river water extractions could be reduced. The engineered options are at substantial capital cost. The less expensive options are: Shortlisted options  Curdievale bores, extracting 10 or 18ML per day (C10 or C18);  North Otway bores, extracting 6, 12 or 20 ML per day (N6, N12 or N20). Other options investigated and costed but not shortlisted  South Otway bore options;  Winter fill storage 3km from the river to supply customers over summer;  Winter fill storage on the river floodplain to supply environmental flows over summer. This shortlist has changed since the May 2016 Options Report. Because of new costs including::  Safeguards to prevent exposure of potential acid sulphate soils, including investigations to set bore license conditions and conservative extraction limits;  Onsite removal of iron and manganese for North Otway and South Otway bore options;  Covering two raw water storages at Warrnambool (Dales Rd) with shade cloth to reduce algal blooms associated with high phosphorous levels for South Otway and Curdievale bore options;  Higher costs for coagulant suitable for treating high alkalinity water from the Curdievale bore;  An updated cost estimate for the construction of winter fill storage options.

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The costs of iron and manganese removal are upwards of $10 million, and the costs of winter fill storage are upwards of $30 million.

Costs vs. environmental benefit for the engineered options is plotted below. “Estuary benefit” is the modelled percentage reduction in low flow days in the estuary over the February and March period.

Gellibrand Options Assessment - possible engineered options

C10 18 C18 16 N6 C18 N12 C18 14 N20 C18

12 N6 N12 10 N20

8 NW NWF 6 Desalination

4 S6

S12 Environmental Benefit theto Estuary 2 S18 Current 0 0 10 20 30 40 50 60 70 80 Net Present Cost ($m)

If $7.3 million dollars were invested, option C10 could be implemented, with environmental benefit to the estuary (the proportion of February/March days where flow is less than 100ML/d is expected to reduce by 9%, from 83% to 74%). Investing $11.7 million into option C18 could improve this to 72%. Other shortlisted options are the N6 C18, N12 C18, and N20 C18 combinations. The costs of implementing these options is substantial. Maintaining the status quo and not investing in engineered measures for flow substitution is a real option.

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The next steps for three selected operational interventions and the lowest cost engineered option are as follows: Possible option next steps status as of July 2019 Summer water - Wannon Water and the Corangamite CMA will work In progress efficiency together to deliver a water efficiency campaign campaign Airspace option - A project to optimise the operation of the Otway System and In progress (drawing down challenge the current storage operation rules existing storages over summer) Modified N6 (no - Assessment of the water quality risks to determine the In progress treatment) extent to which the existing Carlisle River bores (capacity

6ML/d) can be run over summer given the known iron and manganese issues - Discussion with SRW and private irrigators re. protection of Contingent on environmental flows gained through this option (including an above adjusted flow management regime with associated monitoring)

Curdievale bore - A hydro ecological consultancy to better quantify Contingent on - C10 environmental benefits of this option and other related funding options – led by CCMA. Contingent on - Development of a business case comparing costs and above benefits.

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1. Introduction Wannon Water provides drinking water from the Gellibrand River to farms, businesses and industry and to a residential population of 48 000 people. This water is the main supply source for most of the Great South Coast region, which has a gross regional product of $5.3 billion a year (Invest Victoria 2018). The extraction from the river occurs under a Bulk Entitlement issued by the Victorian Government. The Bulk Entitlement allows for extraction of up to 12 580 ML a year, limited by the North Otway and South Otway pipeline capacities. Wannon Water is the largest consumptive user from the Gellibrand; Barwon Water holds a Bulk Entitlement of 5 000 ML a year for water supply to Colac, and there are some private irrigators who hold licences that are administered by Southern Rural Water. All of these licence holders are required to reduce their extractions at very low stream flows. The Gellibrand River is under ecological stress during summer low flow periods, and this stress could be reduced if Wannon Water further reduced its extractions from the river at these times. The Western Region Sustainable Water Strategy Action 7.3 is for Wannon Water to work with other stakeholders to identify preferred options to achieve this. An assessment of options was undertaken (Wannon Water, 2016) that included a range of options including substitution of groundwater from various sources, new storages to harvest water during winter and demand side measures to reduce summer demand. Substitution of groundwater from a bore at the Wannon Water Southern Otway pump station was one of the groundwater options. Little was known about the characteristics of the aquifer in this area so the construction of a test bore and pump test was proposed to understand more about the aquifer in terms of connectivity with shallow groundwater and the river and potential adverse impacts of extraction on ground water dependent ecosystems. Also critical was understanding the potential yield and quality of this groundwater source. 1.1 Previous studies This report is preceded by the May 2016 Options Report. 1.2 Work since May 2016  Funding of $100,000 from the Department of Environment, Land, Water and Planning was secured. Wannon Water provided an additional $350,000 to investigate the feasibility of the “South Otway bore” options;  A Project Control Group was established with membership from Wannon Water, the Corangamite Catchment Management Authority, Department of Environment, Land, Water and Planning, and Southern Rural Water;  A Stakeholder Reference Group (SRG) was established;  A range of community engagement activities were undertaken including information sheets, mail- outs, public information sessions, meetings with the SRG and project updates;  Land and Water Resources Otway Catchment (LAWROC) undertook sampling and testing for potential acid sulphate soils at the South Otway site;  A program for monitoring any impact on potential acid sulphate soils during the pump test was developed in collaboration with the SRG. A study area that encompassed the area within a 500- metre radius of the proposed test bore was surveyed for vegetation classification and wet areas. Five surface water monitoring sites were established;  A test bore and observation bores at South Otway were constructed (see Appendix B);  Further testing for acid sulphate soils was undertaken for a number of sites agreed by the SRG.  The SRG raised a number of new options for consideration (see Appendix D);

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 Water quality issues have been reviewed for water sourced from the North Otway bores (at Carlisle River), the South Otway test bore, and the Curdievale bore (see Appendix E). As a result, new costs have been incorporated into these options that make them substantially more expensive. These costs include o Onsite removal of iron and manganese for North Otway and South Otway bore options; o Covering two raw water storages at Warrnambool (Dales Rd) with shade cloth to reduce algal blooms associated with high phosphorous levels for South Otway and Curdievale bore options; o Higher costs for coagulant suitable for treating high alkalinity water from the Curdievale bore and the South Otway options;  A more detailed investigation of the cost of the construction of winterfill storages has been undertaken by GHD. The revised options for improving summer flows are described in the section three of this report. Assumptions about the options are documented in Appendix F.

2. Community Engagement 2.1 Definition of community engagement At Wannon Water, community engagement is defined as:

A genuine process of working with people to build capacity, strengthen relationships and inform decisions

2.2 Scope and context of the community engagement Support all the relevant community and government stakeholders to:  Have input into risk identification and the scope of the consultant brief to undertake groundwater investigations including a 7-day pump test at the Wannon Water South Otway Pump Station. This investigation was part of the feasibility testing for south otway groundwater substitution – a preferred option (Wannon Water, 2016) to achieve summer flow improvement in the Gellibrand.  Have input into Wannon Water’s subsequent review of options given in this report.

2.3 Design and delivery of engagement activities The community engagement for this project was designed and delivered collaboratively with the members of the project control group A genuine process of and representatives of other key stakeholders. For example advice working with people… was sought from community groups, businesses and landholder representatives about the timing and location of meetings and the style and modes of communications.

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All members of the project team and other consultants working on the …to build capacity, project were involved in the community information sessions and strengthen meetings. This allowed for in-depth technical information to be shared relationships… with the community with the opportunity to ask questions, provide feedback and discuss issues directly with the relevant people.

The expertise and local knowledge the community brought to this … and inform process provided great value to the project, including informing the decisions design of the environmental risk monitoring for the 2017 groundwater investigation and the scope of this review of options.

2.4 Who was engaged Project Control Group - Corangamite Catchment Management Authority, Department of Environment, Land, Water and Planning, and Southern Rural Water; Stakeholder Reference Group – representatives from landholders, local government, businesses and residents, Heytesbury Landcare Network; Estuary Watch, Princetown Landcare group, Friends of the Gellibrand River, Estuary and Wetlands, Curdies Valley Landcare Group and Land and Water Resources Otway Catchment. Project News Group – Additional community members and agencies who were unavailable to join the Stakeholder Reference Group including Parks Victoria and indigenous groups. 2.5 Engagement activities and outcomes A range of community engagement activities were undertaken for this project including establishment of a project news group, four meetings of a stakeholder reference group a site visit and, publication and interpretation of technical reports. Outcomes of the community engagement included: input into the brief for the pump test relating to monitoring for and mitigating risks associated with acid sulphate soil; and input into review of options following the pump test results; establishing cooperation between the CMA and Wannon Water; building relationships with the Gellibrand community and establishing trust and willingness within the community stakeholders to collaborate in the future.. . Further detail of the engagement activities and their outcomes is provided in Appendix C.

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3. Options for improving summer flows 3.1 Business as usual - Current practices contributing to improved summer flows Increasing water efficiency Per person residential water use in the Otway System (averaged over a year) has declined from 200 litres a day in 2006 to 160 litres a day in 2018. Water is being used more efficiently and this trend is likely to continue. This (and other business as usual measures) has resulted in reduced extractions from the Gellibrand:

Residential Use Extraction Population (litres per person (megalitres) per day)

2006 44 200 10 342 200

2010 45 400 9 306 177

2016 47 244 8 927 173

2018 47 850 8 756 160

Ongoing improvements in water use efficiency are being made via programs including leak detection, partnerships with industry, and community education.

Centralised roof water harvesting Within one of the major growth corridors in Warrnambool, the roofs of some 3,000 new homes to be constructed will form an urban catchment that is expected to contribute 471 megalitres of water per year into the Brierly Basin, which supplies the Warrnambool Water Treatment Plant. In an average rainfall year, this provides 100 per cent of the water needs of these houses. The adjacent Gateway Business Park in East Warrnambool collects roof water from industrial sheds. When fully developed, the roofs here are expected to harvest 25 megalitres per year.

Promotion of Integrated Water Management In 2017, Wannon Water appointed an Integrated Water Management Coordinator to work with councils, developers, industry and other stakeholders to identify alternative water sources, especially for irrigation and industry such local groundwater, stormwater capture and re-use and waste water recycling. As part of the business case for Integrated Water Management projects, Gellibrand River summer flow benefits will be factored into the cost benefit assessment.

Cessation of pumping (subject to operational considerations) during artificial estuary openings In consultation with the Corangamite Catchment Authority and Southern Rural Water, Wannon Water participates in coordinated reductions in pumping to increase flows to assist with artificial river mouth openings. The arrangement has been in place since October 2016.

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3.2 Possible operational Interventions

Voluntary water efficiency campaign targeted at summer use An awareness campaign could be aimed at reducing water use over summer for customers connected to the Otway System. This option could include activities such as exchange tours for Warrnambool residents to the Gellibrand valley and could build on existing awareness campaigns such as the Ripple Effect’s Going Upstream program, and/or Wannon Water’s Target Your Water Use campaign (for example, never waste water, especially in summer). Multi-agency involvement and participation in a coordinated campaign may also increase the impact and reach of the messaging. Voluntary measures may be less effective in achieving water savings than a pricing mechanism. Potential reductions in summer extractions resulting from a voluntary water efficiency campaign may be around 0.5 ML/d. Thus this option would provide a very small benefit to the estuary.

Summer vs winter pricing Water price could be higher in summer than in winter, with the aim of increased awareness, and reduced summer demand. From 2010 to 2018, residential consumption in the Otways reduced by 10%, from 200 to 160 litres per person per day averaged over the year (for comparison, metropolitan water efficiency campaigns refer to “target 155”). Summer extractions from the Gellibrand River are up to 35 ML/d, with residential consumption being about one third of this extraction. If “summer vs. winter pricing” resulted in a further ten per cent reduction in summer residential use, the reduction in summer extractions from the river would be in the order of 1 ML/d. Thus this option would provide a small benefit to the estuary. This option would require approval of the pricing regulator and extensive customer engagement with widespread support. There is significant uncertainty around the level of flow benefits to be achieved from this option.

Airspace option The May 2016 Options Report includes an "airspace option" for drawing down existing system storage over summer that could reduce summer demand by up to 4 ML/d. This is a complex issue for Wannon Water and will be explored further in a 2019 project to optimise the operation of the Otway System and challenge the current storage operating rules.

Conversion of private diverter licences to winter fill licences There is approximately 2,130ML of private diverter licences in the Gellibrand drinking water catchment. GHD (2010) “Report on Options for Enhancing Summer Flows in the Gellibrand River” estimated that these licences extract a total of around 6ML/d in summer. These private diverter licences could be converted to winter fill licences in order to protect summer flows. This would imply significant cost to these irrigators, who would have to construct winter fill storages. It is not proposed to pursue this option further as it is likely to be a more expensive option per ML than other options and it is unlikely that all private diverters would be willing to participate. There is a risk for all options that the water gains in the Gellibrand River are simply extracted by other users (irrigation) under existing extraction licences and flow sharing rules. Thus, implementation of any of these options would need to include an adjusted flow management regime with associated education and monitoring.

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3.3 Possible engineered options Engineered flow substitution options for improving Gellibrand summer flows are as follows. Note that these are possibilities to be explored; they are not recommendations. N6 – North Otway bores 6 ML/d The existing Carlisle River bores (which are located at North Otway) could be run at 6 ML/d (the licenced volume) during summer low flow periods. This groundwater could be supplied into the North Otway pipeline in place of water extracted from the river. The water would need to be treated at site before being pumped into the North Otway Pipeline (NOPL) due to high levels of Manganese and Iron. The option includes investigations and monitoring to control risks associated with potential acid sulphate soils.

N12, N20 – North Otway bores 12 or 20 ML/d Implement groundwater substitution of up to 12 ML/d or 20ML/d at North Otway. This will require two or three new groundwater bores, connecting pipelines and increased treatment capacity. The option includes investigations and monitoring to control risks associated with potential acid sulphate soils.

NW - North Otway winter storage Construct a new 1,000 ML offstream storage at North Otway. The best location for this storage is near the ridgeline 2.5km west of the river. This would allow winter flow harvesting to replace summer extractions at North Otway, representing a 12 ML/d augmentation of summer low flows (given the assumptions detailed in Appendix F regarding water availability from the river). Works include construction of new pipeline and pump station to transfer water to the new storage during periods of high winter flow and a pump station to pump water from the new storage into the north Otway pipeline.

NWF - North Otway winter storage (floodplain) Construct a new 1000 ML offstream storage or storages adjacent to the Gellibrand River with associated river pump stations and pipelines. This would allow winter flow harvesting and summer low flow releases to be managed by the CMA. As for the NW option, a 1000 ML storage will provide a 12 ML/d augmentation of summer low flows.

Desalination Use desalination at Warrnambool to provide the required flow substitution. Note that in summer, pipeline flow to Warrnambool comes primarily from the South Otway Pipeline, so the environmental benefit to the river is attributed at South Otway.

C10, C18 – Curdievale bores 10 or 18 ML/d Input up to 10 (or 18) ML/d of groundwater to the South Otway pipeline at Curdievale during summer low flow periods. This would require equipping of the existing emergency bore with an electric pump, balancing tank, pump station and SCADA controls. It would also require a cooling tower to reduce the temperature of the 42.5 degree groundwater and construction of a new bore in 2030, which is when the emergency bore is expected to be needed for system augmentation due to forecast growth in demand. The high phosphorous level of this water requires the covering of raw water storages in Warrnambool to protect against algae blooms. C18 would involve construction of an additional bore.

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S6, S12, S18 - South Otway bores Construction of between one and three bores adjacent to the South Otway pipeline at Valley View Road, with each bore expected to yield 6 ML/d. The water would need to be treated at site before being pumped into the South Otway Pipeline (SOPL) due to high levels of Manganese and Iron. Options S6, S12 and S18 will target the Dilwyn formation. Water quality for options S6, S12 and S18 is expected to be similar to that from the existing Port Campbell bore (which is in the Dilwyn formation). (Note that the test bore referred to in Appendix B was constructed into the Pebble Point formation. Construction of the test bore demonstrated that the Dilwyn formation aquifer is not present at that site, but it is expected to be present at Valley View Road, which is a further 5km away from the river).

Relative risk: North Otway, South Otway, Curdievale Groundwater can be sourced from the North or South Otway areas or Curdievale. North Otway The aquifer is relatively shallow in this location and interaction with the river occurs. GHD (2009) estimates that N6 would be sourcing about 10% of its flow from water that would otherwise end up as baseflow in the river. The risk of causing localised impact on springs and groundwater dependent ecosystems is greater here than where the aquifer is deeper (South Otway). Other risks at this location such as loss of power, fire damage and flooding are similar to the South Otway location but greater than Curdievale. South Otway The aquifer is deeper at this location than at North Otway and has an overlying aquitard. It is less likely to be as significant a recharge source for the river compared to the North Otway location. Thus, the extraction of water from this aquifer has a lower risk of impacting river flows than the North Otway location. For the same reasons, the risk of impacting on springs and groundwater dependent ecosystems is lower. However the South Otway location is not proven. There is a risk that the aquifer characteristics are not as expected with lower yields and/or poor quality water resulting in these options not being viable. Other risks at this location such as loss of power, fire damage and flooding are similar to the North Otway location but greater than Curdievale. Curdievale Curdievale bore accesses the lower tertiary aquifer at a depth of around 800 m which has a groundwater flow generally to the south and is thought to discharge to the ocean well offshore. For these reasons the risk of impacting any rivers or groundwater dependent ecosystems is far lower than either of the Otway locations. The water temperature of around 42º C is addressed by including a cooling tower in the capital works. The risk of power loss and fire damage is still present at this site but lower than at the Otway sites. There is no flooding risk at this site.

Emergency Preparedness for Wannon Water Wannon Water maintains a diverse range of water sources that can be used in an emergency. For example, the existing Curdievale emergency bore is a backup supply for Warrnambool. Construction of a new bore may improve emergency preparedness. If the engineered options are to be further considered, a hydrologic review should re-examine and better quantify the benefits to the environment, and assess the benefits to managing water supply in the event of an emergency.

Cost estimates for implementing engineered options are as follows.

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Costs N6 N12 N20 NW NWF Desalination C10 C18 S6 S12 S18 N6 C18 N12 C18 N20 C18 Installed Capacity 6 12 N 20 12 12 20 10 18 6 12 18 24 30 38 Capital costs o new production bores 150,000 450,000 2,000,000 550,000 1,100,000 1,650,000 2,000,000 2,150,000 2,450,000 new observation bores 60,000 180,000 320,000 480,000 640,000 - 60,000 180,000 Land purchase 76,938 65,027 50,000 50,000 50,000 50,000 Easements, site establishment 15,000 45,000 5,000 35,000 40,000 45,000 5,000 20,000 50,000 Submersible pump, rising main, cables 60,000 180,000 100,000 200,000 60,000 120,000 180,000 200,000 260,000 380,000 Site civil works 40,000 120,000 63,000 63,000 40,000 80,000 120,000 63,000 103,000 183,000 Transfer pipelines 150,000 450,000 1,540,000 526,000 10,000 10,000 10,000 20,000 30,000 10,000 160,000 460,000 Pumps & Cooling tower 11,370,000 630,054 575,000 1,150,000 1,150,000 1,150,000 1,150,000 Power supply 50,000 150,000 3,120,000 385,000 100,000 200,000 50,000 100,000 150,000 200,000 250,000 350,000 Switchboard and SCADA 100,000 300,000 140,000 280,000 100,000 200,000 300,000 280,000 380,000 580,000 Pump testing and Investigations 50,000 150,000 230,000 150,000 190,000 230,000 50,000 150,000 230,000 1000 ML storage 39,499,730 22,374,000 - - - extra works 2030 3,043,000 3,043,000 3,043,000 3,043,000 3,043,000 Remove iron and manganese on-site 7,000,000 10,000,000 16,000,000 7,000,000 10,000,000 16,000,000 7,000,000 10,000,000 16,000,000 Shadecloth cover of storages at Warrnambool 1,650,000 1,650,000 1,650,000 1,650,000 1,650,000 20% contingency (50% for NW,NWF) 1,410,000 2,155,000 3,621,000 27,803,334 11,990,041 806,200 1,400,200 1,663,000 2,466,000 3,869,000 2,810,200 3,555,200 5,021,200 Total Capital Cost (inc. contingency, ex. GST) 8,460,000 12,930,000 21,726,000 83,410,002 35,970,122 40,000,000 6,487,200 10,051,200 9,978,000 14,796,000 23,214,000 18,511,200 22,981,200 31,777,200 Annual Operating costs - - - Remove iron and manganese on-site 200,000 250,000 300,000 200,000 250,000 300,000 200,000 250,000 300,000 coagulant costs to treat alkalinity 40,000 80,000 30,000 60,000 80,000 80,000 80,000 80,000 Marginal cost above cost of pumping from river 3,600 7,200 10,800 9,622 25,643 3,600 7,200 10,800 29,243 32,843 36,443 Personnel costs 5,000 10,000 10,000 2,500 5,000 2,500 5,000 7,500 5,000 5,000 10,000 4% pump & electric, 1 % pipeline - 8,300 24,900 470,200 30,462 1,328,000 33,330 65,930 6,900 13,800 20,700 65,930 74,230 90,830 total opex 203,600 265,500 340,700 480,200 40,462 1,328,000 85,452 176,573 243,000 336,000 419,000 380,173 442,073 517,273 - - - Net Present Cost - 10,323,503 - 15,194,229 - 24,182,991 - 74,972,757 - 30,201,622 - 49,986,338 - 7,310,836 - 11,738,153 - 12,212,533 - 17,798,415 - 26,541,915 - 22,061,656 - 26,932,382 - 35,921,145 NPC per ML of installed diversion capacity - 1,720,584 - 1,266,186 - 1,209,150 - 6,247,730 - 2,516,802 - 2,499,317 - 731,084 - 652,120 - 2,035,422 - 1,483,201 - 1,474,551 - 919,236 - 897,746 - 945,293

new production bores N12,N20:150m deep bores; 300mm diameter; S6,S12,S18: 550m deep bores; 200mm diameter new observation bores N12,N20:150m deep bores; 100mm diameter; S6,S12,S18: 300-500m deep bores; 100mm diameter Desalination cost estimate is $2.50 per KL of delivered water (AWA factsheet says $1 to$4 per Submersible pump, rising main, cables source: GHD2012 KL).

N20: 300m of DN225 and 600m of DN300 including crossing the Gellibrand; 300*200 +600*220 = 200K + 100K for river crossing; NW 3km of DN525; NWF 1km of DN525; C18,S6,S12,S18: assume new bores are adjacent to South pipeline Transfer pipelines and inject straight into it. C10, C18: New pump station required to deliver water into pipeline with some flow from Gellibrand River. Cooling Pumps & Cooling tower required to bring temperature down to around 20 deg.

Switchboard and SCADA NW,NWF: included in cost of pumps

Pump testing and Investigations Investigate aquifer behaviour, PASS, downstream impacts NW,NWF: GHD2018 estimate; allow 160ML a year for evaporation and seepage and assume 70 low flow days a year 1000 ML storage or extra works 2030 giving 12ML/d capacity; C10,C18: A new bore is needed in 2030 to provide for demand growth The cost estimate for this is from GHD 2018 Remove iron and manganese on site (FC2018/02414). C10, C18: Curdievale has high phosphorous and to prevent algal blooms both Dales Rd storages should be covered. Shade cloth cover of storages at Warrnambool The cost estimate is from Netpro canopies 2016 (fc2016/02003). Costs for NW, NWF The GHD estimate (FC2018/10913) assesses costs summing to $83m for NW and $36m for NWF, including 50% contingency

coagulant costs to treat alkalinity S6, S12, S18, C10, and C18: Alkalinity is high and would require more expensive coagulants to be used.

Marginal cost above cost of pumping from river Pumping costs determined using headloss calculations to determine heads and current power costs

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A plot of the engineered options, to give the environmental benefits to the estuary discussed in Appendix G is shown below. There are five options that give the highest estuary benefit for a given cost, and these are plotted in bold.

Gellibrand Options Assessment - possible engineered options

C10 18 C18 16 N6 C18 N12 C18 14 N20 C18

12 N6 N12 10 N20

8 NW NWF 6 Desalination

4 S6

S12 Environmental Benefit theto Estuary 2 S18 Current 0 0 10 20 30 40 50 60 70 80 Net Present Cost ($m)

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Appendix G describes two classes of environmental benefit: estuary benefit and freshwater reach benefit. Alluvium 2012 states that the estuary benefit is more important than the freshwater benefit. For the five shortlisted options (shown in bold in the above graph), the freshwater benefit increases as estuary benefit increases, as shown below. The freshwater benefit is highlighted by the dotted ellipse.

Gellibrand Options Assessment - shortlisted engineered options

0.3 Current 18 C10 C18 16 N6 C18

14 N12 C18 N20 C18 0.2 12

8 Environmental Benefit theto Estuary

0.1 6

2 Environmental Benefit theto Freshwater Reaches 0 0 0 5 10 15 20 25 30 35 40 Net Present Cost ($m)

The costs of implementing these options is substantial. Maintaining the status quo and not investing into engineered measures for flow substitution is a real option.

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3.4 Discussion of Environmental Benefits Alluvium’s “Assessment of the environmental benefits and risks of flows below the summer low flow recommendation in the lower Gellibrand River” (2012) report states that all water supply augmentation options result in a notable decrease in risk, compared to current conditions and the base case. Reductions in extraction will be from either the North Otway Pump Station (NOPS) or the South Otway Pump Station (SOPS). The NOPS is located further upstream of the SOPS and reduced extraction at this point will improve flows over a larger length of the river. In assessing the impact to different areas of the river, Alluvium (2012) identified the following:  The most significant risk of low flows and the greatest benefit of increasing flows is in the estuary. The minimum summer low flow requirements of the lower Gellibrand River determined through the FLOWS study (Earth Tech 2006) are driven primarily by the estuary, which requires flows in the order of 100 ML/d to maintain mouth openings and limit the upstream extent of the salt wedge, throughout the low flow season. Benefits of additional water include, wetted perimeter of the flowing water, important for sand-clay dwelling invertebrates, sufficient median depth in pools to maintain fish populations and sufficient median depth over shallow areas, to allow for native fish passage between pools.

 The assessment of the freshwater reach indicated that summer low flows below 86.4 ML/d are likely to achieve the specific ecological objectives identified in the previous FLOWS study, with a similar level of certainty as a flow of 86.4 ML/d. Furthermore, it appears that flows down to the lowest modelled naturally occurring flow (i.e. 57 ML/d for the autumn season at Burrupa) are likely to be able to support the specific ecological objectives with a moderate level of risk.

While the report is clear that reducing extraction from the Gellibrand River by the largest possible amount produces the best environmental outcome (particularly for the estuarine reach of the Gellibrand River), additional information is required to compare the outcomes of each augmentation option. This additional work should focus on knowledge gaps of both freshwater and estuarine reaches so that environmental benefits can be better understood, and compared in a business case.

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4. Discussion The results of the South Otway groundwater trial and the engagement with the community and government stakeholders relating to that trial significantly shifted the options analysis. Treatment costs and winterfill storage costs for engineered options have been re-evaluated and have increased. Business as usual options and operational interventions have been highlighted in this report. It should be noted that climate change is degrading summer flow conditions over time (see DELWP 2019). Business as usual options for improving summer flows are being implemented. As part of the business case for Integrated Water Management projects, Gellibrand River summer flow benefits will be factored into the cost benefit assessment of these options. Overall the ‘airspace’ option has the greatest potential of the possible operational interventions to improve summer flows though this is at the cost of reduce supply security and algae blooms for those reliant on the Otway pipeline. These risks require significant further work to better understand the implications. This investigation is occurring in 2019. Any changes in relation to pricing need regulatory approval and widespread customer support following extensive engagement. The pricing approach is unprecedented, and it may not be possible due to regulatory constraints (the Essential Services Commission does not allow price shocks – changes of more than 10%). Engagement with customers on this issue may raise expectations that may not be able to be met. Community education programs and campaigns will be more straightforward to implement, however resource implications need to be factored in should this option be pursued. The engineered options that are discussed in this report are at significant capital cost. Funding arrangements for these options are yet to be identified. .. If the engineered options are to be further considered, a hydrologic review should reexamine and confirm the benefits to the environment. Additionally, constructing a new bore may improve the ability to manage water supply in case of emergency, and this benefit should also be assessed. It should also note that the shortlisted engineered options are “modular”, potentially allowing a staged investment over time. The C10 option is two-stage. Approximately half of the capital expenditure of $6.5 million would occur on project commencement, and the remaining expenditure will not occur until 2030 (when a new emergency bore is needed to meet expected population growth). The N6 option that is presented above factors in the high cost of onsite removal of iron and manganese. However the iron and manganese from this source water may be manageable if operated for short periods of time via dilution in system storages. A modified N6 option would involve running the Carlisle River bores for short periods without onsite treatment.

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Curdievale bore - A hydro ecological consultancy to better quantify Contingent on - C10 environmental benefits of this option and other related funding options – led by CCMA Contingent on - Development of a business case comparing costs and above benefits.

5. References Alluvium 2012. Assessment of the environmental benefits and risks of flows below the summer low flow recommendation in the lower Gellibrand River. Report prepared for Corangamite Catchment Authority. GHD 2017. South Otway Groundwater Investigation – Bore Installation and Testing. Report prepared for Wannon Water. DELWP 2011. Western Region Sustainable Water Strategy. DELWP 2018. Western Region Sustainable Water Strategy Five Yearly Assessment Report. DELWP 2019. Long Term Water Resource Assessment. Wannon Water 2016. Improving Environmental Flows in the Gellibrand River: Assessment of the Water Supply Augmentation Options.

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Appendix A: WRSWS Action 7.3: Progress Report The Western Region Sustainable Water Strategy five yearly assessment report (DELWP 2018) says Action 7.3 of the Strategy is not yet completed.

This report has been written to fulfil the intent of Action 7.3.

Appendix B: Outcomes from the South Otway groundwater investigation November 2017

A test bore was constructed in 2017 at the South Otway Main Pump Station. This work was exploratory in nature and began with the hoped-for outcome of a 120m bore yielding in the order of 6ML/d of good quality water (based on the bores at Carlisle River). The test bore (as constructed) was roughly twice as deep, 1/3 the yield, and produced poor quality water that would require on-site treatment (to remove iron and manganese) before it could be put into the water supply. Note that the test bore was not constructed into the target aquifer (the Dilwyn formation) but rather into the Pebble Point formation. Construction of the test bore demonstrated that the Dilwyn formation aquifer is not present at this location (but it is expected to be present further away from the river, at Valley View Road). The investigations showed that the use of the bore would not result in local interaction with the river, but that there is potential for interaction further downstream, where the aquifer comes to the surface. The presence of potential acid sulphate soils was confirmed in the area, requiring further investigation of downstream environmental impacts if regular use of the bore were proposed. The test bore is not equipped with a pump and further use of this bore is unlikely. In addition to the test bore, four observation bores were constructed. The SRG met on 28 November 2017 to discuss the outcomes of the groundwater investigation.

Photos from Stakeholder Reference Group Site Visit, May 2017. Inspecting soil samples from the pilot bore.

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The local communities' experience with ground water pumping in the Barwon Downs causing acid sulphate soil activation and subsequent environmental damage generated strong interest in the project. There was mistrust of the urban water corporation and their regulators. The genuine consultation undertaken through this project has resulted in a group of community stakeholders in the Gellibrand catchment interested in continuing to work with Wannon Water on other options for improving summer flows. There were also conversations with riparian landholders about catchment management for improved water quality in the river.

Note that the test bore was drilled close to the river in the hope of intersecting the Dilwyn Formation, but this aquifer was not intersected. Options S6, S12 and S18 will be further away from the river and will target the Dilwyn formation. Water quality for options S6, S12 and S18 is expected to be similar to that from the existing Port Campbell bore.

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Appendix C: Community Engagement Definition of community engagement At Wannon Water, community engagement is defined as:

A genuine process of working with people to build capacity, strengthen relationships and inform decisions

Scope and context of the community engagement Support all the relevant community and government stakeholders to:  Have input into risk identification and the scope of the consultant brief to undertake groundwater investigations including a 7-day pump test at the Wannon Water South Otway Pump Station. This investigation was part of the feasibility testing for south otway groundwater substitution – a preferred option (Wannon Water, 2016) to achieve summer flow improvement in the Gellibrand.  Have input into Wannon Water’s subsequent review of options given in this report.

Design and delivery of engagement activities The community engagement for this project was designed and delivered collaboratively with the members of the project A genuine process of control group and representatives of other key stakeholders. working with For example advice was sought from community groups, people… businesses and landholder representatives about the timing and location of meetings and the style and modes of communications. All members of the project team and other consultants working on the project were involved in the community …to build capacity, information sessions and meetings. This allowed for in-depth strengthen technical information to be shared with the community with relationships… the opportunity to ask questions, provide feedback and discuss issues directly with the relevant people. The expertise and local knowledge the community brought to this process provided great value to the project, including … and inform informing the design of the environmental risk monitoring for decisions the 2017 groundwater investigation and the scope of this review of options.

Who was engaged Project Control Group - Corangamite Catchment Management Authority, Department of Environment, Land, Water and Planning, and Southern Rural Water;

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Stakeholder Reference Group – representatives from landholders, local government, businesses and residents, Heytesbury Landcare Network; Estuary Watch, Princetown Landcare group, Friends of the Gellibrand River, Estuary and Wetlands, Curdies Valley Landcare Group and Land and Water Resources Otway Catchment. Project News Group – Additional community members and agencies who were unavailable to join the Stakeholder Reference Group including Parks Victoria and indigenous groups. Summary of engagement activities and outcomes The table below gives a summary of the engagement activities and their outcomes.

ACTIVITY TIMING OUTCOMES

ESTABLISHING CONNECTION WITH THE COMMUINITY Mail-out and November Community stakeholders informed of the project and Factsheet 2016 invited to express interest in being on the stakeholder reference group and/or the project news group. Phone calls and November Phone conversations with Traditional Owner groups, email 2016 landholders, business owners, Landcare groups and other government stakeholders. The style, content, timing and Community location of engagement activities input was informed by the community.

Stakeholder 17th Held at the Princetown Recreation Reserve. Attended by reference group November 14 community members. 2016 - Establishment Purpose and proposed scope of the investigation presented and discussed. - 1st meeting Highlighted concerns about acid

sulphate soils and potential impacts Community input to groundwater dependent ecosystems. Need to engage Carlisle River Community landholders – hold community input information session there.

Webpage November A project webpage on the Wannon Water website with established 2016 links to project documents.

Establishment November 55 community and government stakeholders subscribed of a project 2016 to project news group. news group Media releases November Project announced and community information session 2016 advertised. Mail box drop November Community information session advertised. 2016

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ACTIVITY TIMING OUTCOMES Community 7th Held at Carlisle River Hall, 10 community members information December attended. session 2016 Community input from this session taken to the following Stakeholder Community input Reference Group meeting for further consideration

WORKING WITH THE COMMUNITY TO REFINE THE BRIEF Stakeholder 7th Held at Carlisle River Hall, 7 community member reference group December attended. 2016 - 2nd meeting Views from the Gellibrand valley included in Wannon Water’s Community input consultation on 5 year planning. Key message - consider water restrictions in Warrnambool over summer for environmental reasons. Agreement to establish a study Community area of 500m radius from the test input bore where sensitive areas would be identified with the community. Sites to have soil tests for acid sulphate soils risk and to be monitored for impacts during the pump test. Agreement from the project team Community that if groundwater substitution goes input ahead in summer periods then assurance is required from Southern Rural Water that other irrigators will not access the environmental flows. Project News April 2017 Report on the outcomes of community engagement Update 1 above and findings from preliminary survey of the study area. Site visit 17th May Site visit at the test bore location during drilling. Six 2017 community members attended. Inspection and discussion of soil samples from the pilot bore drilling.

Walk around the 500m radius study area. Soil tests performed by the LAWROC community group Community presented and discussed. Four input sites of concern brought to the attention of the project team to be monitored.

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ACTIVITY TIMING OUTCOMES Agreement for the project team to meet with the LAWROC group to Community discuss in more detail the results and input implications of the soil tests performed by the group. Project News July 2017 Report on the findings of the survey of the study area, Update 2 map of sensitive sites and a proposed monitoring protocol for environmental risk management. Meeting with 20th July Agreement on the sites to be soil LAWROC group 2017 tested and monitored (additional Community input sites). Agreement that Wannon Water would stop pumping immediately if the Community monitoring indicates a risk of input activating acid sulphate soils

Project News August Report on outcomes of the meeting with LAWROC Update 3 2017

REVIEWING OF TRIAL RESULTS AND OPTIONS ANALYSIS Pump test November Hydrogeologist’s report on the results of the pump test. report and 2017 Three documents circulated: the full report (drop-box interpretation link); a 14-page summary report and; a one-page interpretation and response from the project team. Stakeholder 28th Held at Chapple Vale Hall, 12 community member reference group November attended. 2017 - 3rd meeting Results of the pump test and implication for the project presented and discussed. Input into review of options analysis including further investigations into Community winter storage and demand input management. Feedback of community engagement process including: a well-informed, Community open process was highly valued, input Warrnambool water customers should have been more involved and; more local meetings about resource management would be valued. Project New December Report on outcomes of the 3rd Stakeholder Reference Update 4 2018 Group meeting

Revised options February This report circulated, Gellibrand River Summer Flows report 2019 Improvement – assessment of options, November 2018.

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ACTIVITY TIMING OUTCOMES Wannon Water’s revised options analysis with updated costing and scope of options in light of the results of the ground water investigations and community input. Stakeholder Proposed A 4th stakeholder reference group meeting is proposed reference group with the following purpose: March

- 4th meeting 2019 Review and discuss this revised options report and; Consider the future of this stakeholder reference group.

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Appendix D: New options November 2017 The Stakeholder Reference Group raised a number of options in November 2017 that are listed here and are discussed in Section 2.

 Increasing water efficiency  Centralised Roof water Harvesting  Promotion of Integrated Water Management  Summer vs Winter Pricing  Voluntary water efficiency campaign targeted at summer use  Airspace Option  North Otway Winter storage on the floodplain to be managed by CMA  Desalination

Ideas raised in November 2017 that are not carried into Section 2 are briefly discussed here.

Aquifer recharge schemes An aquifer recharge scheme would need high yield (upwards of 6ML/d) in order to have benefit to the Gellibrand River. The only known suitable shallow aquifer (remote from the river itself) is in Warrnambool and this aquifer has low yields relative to other substitution options. (There are three bores in use at the Warrnambool WTP which each yield 1.5 ML/d.)

Within the Gellibrand catchment, aquifer recharge happens naturally on a large scale, with rainfall and floodplain flows replenishing the aquifer. Engineered schemes are unlikely to have any impact except at a very local scale, and the shallow aquifer is unconfined, so artificially recharged groundwater would rapidly dissipate over a large area and not be easily extracted later in the season.

Further studies into impacts on the estuary This project takes the view that existing studies already demonstrate the impacts of improved environmental flows on the estuary, and provide sufficient information for evaluation of options. While further studies will be welcomed, they are not needed for the purposes of this project.

Also note that, parallel to this project, Wannon Water has agreed, where operationally possible, to cease extractions for two days when the estuary mouth is opened, providing significant benefit.

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Rainwater tanks and third pipe systems Work for the Urban Water Strategy 2017 shows that third pipe systems (i.e. reticulation of recycled water) are prohibitively expensive for Warrnambool compared to other options. 6- star building regulations encourage construction of rainwater tanks for toilet flushing and garden watering.

Limiting growth Wannon Water's view is that the growth of towns is to be supported. However we agree that measures that promote water efficiency and reduce stress on the environment are needed to ensure that growth is sustainable.

Implement Water restrictions The water restrictions that occurred during the millennium drought in Melbourne and other regions in Victoria were at very high cost to the community. Because of this experience, government policy is to avoid the use of water restrictions to manage demand shortfalls. Voluntary measures, pricing measures, and engineered solutions should be put in place such that the frequency of water restrictions is less than one year in every twenty years.

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Appendix E: Water quality issues

Water quality issues have been reviewed (FC2018/01688) for water sourced from the North Otway bores (at Carlisle River), the Curdievale bore, and the Port Campbell bore. Parameters of concern are shown below. Note that (as shown in the table) Carlisle River, Curdievale and Port Campbell water quality is expected to apply to the N, C, and S options respectively. Acceptable Carlisle River Curdievale Port Campbell South Otway Parameter Value Bore 2 South Bore 1 Bore No. 3 Test Bore Total Dissolved Solids (mg/L) 240 76 - 110 290 - 330 300 310 - 320 Total Phosphorus (mg/L) 0.13 0.006 - 0.007 0.29-.74 0.049 0.1 - 0.481 Manganese - Soluble (mg/L) 0.02 0.024 - 0.028 0.009 - 0.012 0.029 0.168 - 0.171 Total Iron (mg/L) 2.1 2.20 - 3.25 0.25 - 0.33 2.6 13.58 - 13.66 Alkalinity (mg/L CaCO3) 40 11 - 16 180 130-160 16-22 Options to which this applies N6,N12,N20 C10,C18 S6,S12,S18 n/a If a box is shaded green, the parameter is within acceptable limits. If it is shaded orange, it is of concern. If it is shaded red, then treatment is required. As a result of this review, new costs have been incorporated into these options that make them more expensive: N6, N12, N18, S6, S12, and S18: Onsite removal of iron and manganese is now costed in. C10, C18: Covering two raw water storages at Warrnambool (Dales Rd) with shade cloth to reduce algal blooms associated with high phosphorous levels is costed in. S6, S12, S18, C10, and C18: Alkalinity of this water is high. Some higher costs for coagulant suitable for treating high alkalinity water are costed in. C20, S18: The TDS levels for water sourced from South Otway and Curdievale of up to 320mg/L are above the level normally supplied to Warrnambool (of up to 240mg/L) but are lower than in some other Wannon Water supplies. TDS is reduced by dilution with other water sources, but options C18 and S18 involve supply to the Warrnambool WTP without dilution. If C18 or S18 is to be implemented, without treatment to reduce salts (reverse osmosis), customers may notice a change in water taste. Taste testing should be done at different dilutions with Gellibrand water to determine actual palatability and anticipate customer responses. Based on the results obtained from the taste testing if it is found that higher ratios of bore to surface water are not acceptable to the Warrnambool community palate then RO treatment might be applied to treat the bore water prior to it entering the supply system to avoid taste complaints from the community. This has not been costed into the options, but it is a risk.

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Appendix F: Assumptions about the options

Number of days per year that flow substitution is required The aim of this project is to implement flow substitution (and hence reduce river extractions) whenever flows at Burrupa are less than 100ML/d (as recommended by Alluvium 2012). This will reduce the extent of the salt wedge in the estuary, and reduce the risk of estuary mouth closure. Historic flows at Burrupa (from D2016/023755) are as follows.

Site 235224 GELLIBRAND RIVER @ BURRUPA flows <100 in pink; flows >600 in blue

fy ending: 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 July 279 1573 4125 916 908 411 564 695 10675 518 951 12107 629 377 1526 218 907 1551 2413 649 473 2369 2853 728 416 985 1360 2068 373 571 288 346 348 2021 378 1740 245 210 474 480 233 454 908 1413 188 2547 347 July 894 1952 1262 2299 525 1539 1187 478 1066 3033 625 5948 2226 407 2046 1092 427 3139 686 460 859 6011 2362 1601 1291 421 2496 1696 270 582 218 340 278 3075 281 2068 275 462 1757 433 898 499 3451 1493 884 3020 386 July 855 1872 1153 1346 540 1027 1607 348 1395 2688 422 1455 1161 316 1191 587 568 2241 990 593 745 1391 1136 1955 915 357 2825 1670 328 735 177 232 405 823 280 1836 247 477 977 726 1555 449 2660 1138 754 1610 785 July 477 3057 1123 2022 1520 7435 1216 320 986 2310 455 1636 780 336 1456 895 3556 1296 2484 475 880 1416 892 2072 696 646 4518 2961 465 388 539 1078 857 1748 336 3536 381 1394 898 726 503 679 1616 1021 918 2007 792 July 1061 1467 1423 1154 630 4155 755 265 6166 2033 563 1166 1744 313 1164 1565 1137 4137 818 2086 466 2040 1980 1197 553 723 1819 1502 308 557 290 1894 383 939 1933 2381 1180 374 517 781 620 357 1412 1944 425 2595 1077 August 1002 3625 1259 664 1529 2151 1603 1291 3142 798 1438 2146 761 567 850 757 1282 1437 828 935 1448 1237 2510 2273 976 3495 3996 4569 296 1068 291 403 516 898 985 1146 1078 609 1514 842 1300 2777 842 942 2159 1303 1574 August 944 1357 1374 1985 2248 3848 1294 1513 987 7212 2957 1453 2778 268 1859 603 3180 697 1045 1212 1788 4016 5095 2097 1015 2309 3696 4757 602 494 442 730 1564 1071 819 1976 1325 367 1290 2028 685 20147 1062 1758 3688 780 708 August 875 4548 975 778 1076 5576 1037 842 719 3505 1457 2854 3505 237 1589 1009 1682 1921 584 961 703 2372 4736 2315 2375 2006 858 2512 699 384 768 1625 1798 1050 1099 3597 768 356 1060 1709 1268 3463 1497 1943 2245 875 575 August 438 1473 2794 614 698 1255 3543 1098 1206 1348 1035 1846 3613 186 1024 2803 2067 857 2244 945 2736 3636 4940 3098 824 1534 640 1846 1359 606 371 1088 4662 511 2826 841 868 496 488 1204 2271 2816 638 2029 5688 655 498 September 840 4890 2255 563 2401 3138 3251 584 488 899 1228 2482 2540 164 712 1571 1711 1424 1143 703 5514 1486 2064 4527 2261 588 631 1226 1541 246 277 1622 825 687 2364 1150 1189 250 348 950 3235 2632 470 2339 1106 464 602 September 2355 1997 1397 748 3190 2760 2033 1448 1171 691 2813 1767 966 523 2999 1092 727 2144 1836 478 813 1553 1135 1381 1594 496 989 1461 1966 284 374 2939 1112 938 743 1031 431 710 239 446 1819 3832 556 1552 643 417 677 September 3964 2519 1369 497 1603 6995 1746 928 833 1752 4309 1908 606 238 3736 959 525 1721 1292 882 1648 750 1193 2531 1040 927 646 6205 1794 1738 259 2601 514 523 2257 3090 2050 299 712 425 716 1235 465 777 698 381 525 September 2465 1022 441 927 3979 1809 3774 757 970 805 3407 492 214 1661 5954 383 1572 647 424 1238 832 6579 3470 4010 2035 817 2541 526 1992 207 727 349 849 1104 923 1062 347 472 681 751 806 442 658 3417 308 342 October 1768 2518 299 561 2574 752 712 663 722 2396 907 718 408 922 2550 483 632 603 378 696 688 1596 3356 742 2216 425 1800 355 622 142 755 482 2100 1486 599 1154 233 1477 367 1358 808 1058 1759 1568 288 265 October 799 4875 330 375 1191 958 1832 640 450 2174 2360 1024 193 555 959 332 1978 671 368 801 557 777 1226 1042 2783 491 1528 281 871 93 1259 593 619 874 452 599 193 2115 365 569 563 532 612 1362 300 170 October 365 678 1613 1027 488 803 3122 1129 322 465 6326 2517 428 166 543 550 269 987 417 559 3144 2795 545 3273 521 1262 867 898 281 1924 229 1430 1464 1484 667 372 1120 121 657 235 786 725 404 1751 636 272 135 October 266 492 1236 307 1001 792 2329 3034 847 434 921 686 729 749 1084 618 335 2293 1519 723 2965 1959 458 1823 1156 555 358 673 316 963 184 910 1104 605 737 257 516 158 335 165 745 716 293 589 512 188 106 October 798 398 1411 222 1891 608 4658 723 314 2050 684 749 368 271 509 376 798 3551 442 414 2973 725 445 622 837 416 381 490 171 996 168 2167 1364 742 703 971 565 115 251 142 379 380 311 420 1565 222 89 November 561 336 2288 198 758 563 3391 604 219 363 365 1229 249 165 602 340 354 888 293 275 1149 471 1249 1638 2775 560 312 412 351 347 110 1696 880 524 2677 382 360 105 2047 170 391 1070 487 391 551 130 88 November 318 303 1419 349 517 550 2066 394 501 539 1241 751 570 142 828 272 487 572 225 200 577 740 787 946 782 2303 2970 365 197 271 229 508 821 342 520 452 457 159 692 165 209 413 396 290 600 111 58 November 466 5059 1412 205 412 407 707 379 196 921 583 436 374 142 1914 231 445 431 157 274 722 307 358 780 435 462 474 579 215 471 133 418 1887 267 316 564 280 319 294 91 148 387 227 242 686 130 78 November 360 492 795 166 296 269 1115 286 158 443 308 288 191 88 490 393 290 306 212 1814 313 307 273 1519 315 388 334 339 125 239 472 201 1354 250 272 263 189 85 246 284 205 466 199 184 1585 96 119 December 464 313 390 129 349 266 420 372 527 333 256 326 145 73 366 192 420 221 1047 635 304 208 227 576 236 286 267 415 134 215 124 125 922 216 187 254 187 67 149 224 333 322 323 165 459 137 117 December 381 306 653 119 223 205 316 255 194 347 202 188 139 1150 245 192 1329 482 302 516 186 196 189 990 192 188 262 609 117 164 99 78 693 343 136 363 150 54 140 263 158 1244 196 169 399 93 131 December 306 371 348 104 187 248 268 316 143 2204 270 258 144 176 163 622 846 839 172 285 171 161 1429 441 384 126 228 274 112 114 125 55 428 207 137 177 144 51 94 1448 158 516 140 379 396 119 December 241 254 548 89 437 225 198 263 135 623 199 144 104 73 104 281 841 447 119 188 109 197 570 773 324 251 330 233 106 113 93 134 315 137 510 111 115 47 1250 242 163 484 126 137 401 132 December 188 398 379 103 235 289 136 237 189 341 262 115 78 58 68 194 424 265 107 195 174 123 289 466 1154 125 188 163 65 180 209 167 359 140 69 106 110 51 183 184 87 265 104 101 227 149 January 1725 715 262 98 142 141 104 146 133 197 97 88 88 56 68 157 322 2228 126 413 63 761 387 328 457 112 175 123 50 65 213 40 374 122 56 296 95 43 88 134 71 192 93 100 280 187 January 606 275 682 159 125 329 108 191 73 165 823 102 96 159 47 108 300 399 79 268 63 118 406 281 404 69 125 91 62 67 72 21 256 83 81 117 79 43 83 99 62 1591 316 115 178 161 January 318 115 226 89 115 141 83 284 66 725 189 72 63 50 105 73 218 253 77 132 54 78 222 251 270 68 102 93 62 49 69 15 176 86 52 110 47 125 84 85 136 697 107 121 148 115 January 201 165 161 58 80 111 131 149 91 139 193 103 102 37 81 63 155 200 114 65 45 670 175 398 176 119 203 223 81 60 98 24 142 64 66 113 66 119 69 102 57 297 78 133 105 128 February 154 2136 134 76 126 95 93 143 125 110 142 97 66 38 55 46 98 150 60 51 5628 256 135 192 135 75 212 112 61 67 60 5 116 135 105 1911 103 71 69 111 54 201 93 186 92 66 February 123 731 125 143 112 84 120 90 177 83 131 126 44 31 46 55 82 86 70 75 1452 166 149 128 156 72 969 104 81 76 47 23 660 87 96 598 114 58 117 121 69 193 110 182 96 67 February 158 317 462 69 125 84 96 130 204 76 84 72 31 28 46 54 58 77 60 69 422 228 137 115 153 129 292 73 73 89 48 64 174 93 84 240 90 76 109 141 383 179 102 189 92 66 February 139 225 309 112 144 85 94 125 77 77 92 78 41 28 43 55 90 175 50 43 213 101 109 241 113 36 146 95 62 78 52 9 175 150 68 173 94 58 178 152 76 189 88 52 104 72 March 97 172 638 151 166 90 179 104 89 94 79 75 31 31 66 91 76 111 51 32 161 78 114 371 168 19 180 113 63 145 54 32 134 205 47 128 98 79 178 177 69 156 80 54 75 150 March 181 140 237 97 112 97 101 92 60 154 94 82 56 37 41 93 67 136 99 162 148 134 113 182 111 236 104 105 61 63 57 38 82 97 67 166 118 84 188 212 219 318 109 71 82 129 March 142 211 193 147 119 261 74 146 94 571 88 114 45 36 160 135 48 102 119 88 121 127 116 135 114 118 309 111 60 76 56 87 84 89 83 131 154 102 194 287 80 146 121 104 109 161 March 657 142 176 160 100 152 113 158 95 125 75 104 68 1770 86 106 53 137 55 72 102 249 90 161 83 212 189 136 56 74 55 318 96 177 106 99 24 145 247 94 69 271 202 149 149 278 April 275 119 155 360 158 163 131 267 148 122 91 108 135 164 328 83 57 366 49 69 192 178 121 157 68 316 191 146 91 74 55 71 86 120 375 90 29 83 150 81 102 176 194 176 164 82 April 243 122 151 145 264 344 186 185 143 222 92 90 54 199 112 714 82 182 44 117 108 259 748 158 152 532 217 235 114 77 52 54 65 109 71 105 160 62 193 84 86 155 210 202 176 95 April 176 105 227 166 457 122 102 236 316 164 73 86 47 251 74 243 102 183 42 161 214 130 185 137 234 289 339 157 245 76 49 99 81 202 52 105 175 50 141 83 220 841 244 88 145 106 April 377 491 162 1286 132 122 110 159 118 192 550 106 70 155 141 1044 292 173 45 164 164 173 190 125 234 358 708 144 214 95 56 228 69 146 95 136 469 57 93 122 96 310 94 60 108 185 April 1563 1301 656 835 300 134 164 192 202 196 784 91 280 218 220 306 736 150 103 109 759 190 187 112 170 251 390 121 149 110 38 1314 193 116 168 107 102 60 145 491 226 232 335 155 132 130 May 1259 1608 236 2520 446 142 247 185 137 316 307 89 166 856 150 204 215 352 126 176 309 206 246 143 220 401 266 652 96 81 121 185 90 125 329 124 381 141 279 131 220 249 424 83 295 585 May 676 2309 196 697 277 308 151 215 220 432 421 306 384 385 154 238 601 318 170 444 260 156 454 160 326 289 238 421 131 126 201 126 85 105 157 111 578 52 208 116 581 595 226 84 186 500 May 1215 695 430 1598 568 1553 241 171 223 250 526 156 188 413 157 376 1208 745 168 165 368 226 389 147 847 376 194 231 93 324 319 254 328 133 156 105 264 105 347 428 239 497 285 460 125 453 May 827 409 324 1239 368 714 631 340 363 241 662 152 370 225 214 254 733 1382 171 272 314 218 301 213 577 361 298 222 512 198 344 190 229 220 208 130 206 162 166 197 162 1040 667 192 377 381 June 496 6943 228 1028 231 501 293 2311 653 436 323 306 537 484 186 300 461 1051 208 454 485 246 374 202 660 357 263 321 231 513 1098 238 168 156 264 161 161 366 149 157 349 496 341 257 263 373 June 356 2079 195 1849 192 695 808 734 1151 369 302 189 213 1137 230 501 564 523 1028 423 452 1772 1226 328 287 1726 845 231 543 184 830 311 370 495 266 195 138 159 106 1209 329 1606 2956 419 279 244 June 1294 1031 196 2199 244 518 564 837 450 456 362 486 316 1501 262 645 560 758 871 719 528 1009 1507 472 591 1562 403 510 590 1127 323 750 833 845 1218 310 208 237 261 439 330 549 493 854 444 395 June 774 3852 235 1397 812 525 358 1563 457 307 512 349 977 563 243 856 3264 2081 750 936 766 1474 769 787 588 713 390 264 985 540 233 773 658 306 2222 822 256 515 324 236 597 3928 1533 238 282 289 fy ending: 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 no. of weeks <100 1 0 0 7 2 6 5 2 8 4 10 11 15 14 12 9 10 2 13 9 4 2 1 0 2 6 0 4 16 16 19 16 9 7 14 2 9 20 7 7 12 0 6 7 5 8 4 This data shows that there are about seven weeks a year when flow is less than 100 ML/d at Burrupa. This varies between zero and 20 weeks depending on the year. In 75% of years, the low flow period lasts for 10 weeks or less. This options assessment assumes that flow substitution is required for up to ten weeks (70 days) per year, catering for 75% of years.

Groundwater substitution options: Concerns raised by the Stakeholder Reference Group during the South Otway pump testing reinforce that risks of groundwater-surface water interaction (including risks of possible exposure of potential acid sulphate soils to the atmosphere) should be avoided. In this context, there is a groundwater trigger level associated with the licence for the Carlisle River bores that requires pumping to stop when the water level in Observation Bore 8 falls to a level that is about one meter above the river water level. N6 was pump tested at 6ML/d over five months (150 days) in 2015 and the groundwater trigger level in OB8 was not reached. N6 therefore meets the 70 days per year flow substitution requirement. N12 was pump tested at 12 ML/d for seven days in 2009 using the two existing Carlisle River bores and GHD2009 concluded that the groundwater trigger level in OB8 would be reached after 19 days. This is a much shorter period than the 70 days per year flow substitution requirement. Even though the two existing Carlisle River bores can each yield 6 ML/d, the risks of groundwater/surface water interaction mean that option N12 will require the construction of a new additional bore, in a new bore field nearby. N20 will require the construction of three additional bores. For S6, S12, and S18: Bore field spacing to reduce groundwater/surface water interaction is built into these options, and there is less interaction between the target aquifer and the river at this location. It is assumed that these options will meet the 70 days per year flow substitution requirement. For C10, C18: Groundwater/surface water interaction does not occur at this site. Bores at Curdievale can deliver their target yield continuously.

Winter storage options: For NW, assume that flow substitution is required for 70 days per year. After allowing 160ML/yr. for evaporation and seepage, a 1000 ML storage could deliver 12 ML/d over this period, or 17ML/d over 50 days.

Desalination option: Desalination would take place at Warrnambool, which in summer is supplied primarily via the South Otway pipeline, so any environmental benefit applies at the South Otway offtake point (in common with the C and S options). Assume that 18 ML/d of flow substitution is required. A desalination plant could deliver this yield continuously for more than 70 days per year.

The Otway System BE and Option NW Wannon Water’s Urban Water Strategy 2017 notes that demand in the Otway System is growing and that augmentation of the Otway System may be required as early as 2030. This report therefore designs the flow substitution options for “system at capacity” conditions, not for current conditions.

The Otway System being operated at capacity involves full utilisation of the provisions of the existing Bulk Entitlement. The Otway System Bulk Entitlement specifies a combined annual surface water extraction limit from North Otway, Arkins and South Otway of 12 580 ML/year. It also specifies a combined daily extraction limit of 22.5 ML/d from the three Arkins Creek offtakes and the North Otway offtake, and a daily extraction limit of 21.5ML/d at South Otway offtake. The daily extraction limits correspond to the pipeline capacities.

Groundwater substitution options will not be affected by pipeline capacity constraints because the groundwater will be pumped into the pipeline at the same time as the extraction from the river is reduced. However winter storage options will require extraction greater than the current limits, so a BE amendment would be required for these options.

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Appendix G: Environmental Flow Benefits

The September 2012 Alluvium Report “Assessment of the environmental benefits and risks of flows below the summer low flow recommendation in the lower Gellibrand River” says: The Gellibrand River in the Otway Ranges is considered to be among Victoria’s most important rivers for the conservation of native fish. Flow in the Gellibrand River has declined in recent years as a result of increasing extraction for urban and rural use and storage in farm dams in the upper catchment. In particular, significant flow reductions have been observed in the summer months and a low compliance rate with the identified summer low environmental flow requirements. A low compliance rate has the potential to seriously impact the high environmental values of the Gellibrand River, particularly given the forecast pressure of climate change… The assessment findings suggest that the minimum summer low flow requirements of the lower Gellibrand River are driven primarily by the estuary, which requires flows in the order of 100 ML/d to maintain mouth openings and limit the upstream extent of the salt wedge. Flow management in the lower Gellibrand River should therefore target the provision of at least 100 ML/d at Burrupa, throughout the low flow season. The analysis suggests that the low flow requirements in the freshwater reach are not as high, with flows between the lowest naturally recorded flow and the existing recommendation (i.e. 57 to 86.4 ML/d) providing similar levels of certainty of achieving the specific ecological objectives identified in the 2006 FLOWS study. The Alluvium Report presents results for two metrics that can be used to compare the environmental benefits of the augmentation options. The most important metric is “% of days in February and March with flows below 100 ML/d at Burrupa”. The results for this were: Modelled natural conditions1 26% Modelled current conditions 83% N6 (6ML/d augmentation) 78% Full substitution at NOPS 73% Full substitution at SOPS 72% Full substitution at both NOPS and SOPS 65%

Note 1: without any farm dams or river extractions.

NOPS = North Otway Pump Station. SOPS = South Otway Pump Station.

The lower this metric is, the better it is for the environment. This metric (which in this report is used to give the “Estuary Benefit”) is important due to Alluvium’s conclusion that flow management should target the provision of at least 100 ML/d at Burrupa. The second metric presented by Alluvium is the proportion of days in February and March which have moderate environmental risk in the freshwater reach. The risk relates the objectives of the 2006 FLOWS study, involving the provision of adequate habitat for macroinvertebrates and fish, and the maintenance of water quality. This is measured at Burrupa and is reported here as the “Lower freshwater reach benefit”. Assuming that the

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ecohydrology has no spatial variation along the length of the river, the metric can also be evaluated at the North Otway Pump Station, and is reported here as the “Upper freshwater reach benefit”. Any improvement in flow at the North Otway Pump Station will benefit both the upper reach (from NOPS to SOPS) and the lower reach (from SOPS to Burrupa) while an improvement in flow at the South Otway Pump Station will only provide benefit to the lower reach. The combined freshwater benefit is calculated in the below table as the sum of upper and lower reach benefits. As shown in the table, the desalination, Curdievale, and south options do not provide freshwater benefits upstream of the South Otway offtake. The way these metrics are used in this report are shown in the below table. “Estuary benefit” is the modelled percentage reduction in low flow days in the estuary over the February and March period. “Freshwater benefit” is a measure of reduction in “moderate risk” conditions in the freshwater reaches (note that estuary benefits are of greater significance than benefits in the freshwater reaches).

Current N6 N12 N20 NW NWF Desal C10 C18 S6 S12 S18 N6 C18 N12 C18 N20 C18 Project Benefits Proportion of Feb/Mar days below 100 ML/d at 83% 78% 74% 73% 72% 65% Burrupa (Alluvium 2012 Table 4) Improvement over current (“Estuary 5 9 10 9 9 10 9 11 5 9 10 14 16 18 Benefit”)

Proportion of Feb/Mar days of moderate environmental risk 8% 3.9% 1.7% 0% 0% 0% (at Burrupa) (Alluvium 2012 Table 11)

Lower freshwater 0.00 0.04 0.06 0.08 0.06 0.06 0.08 0.06 0.08 0.04 0.06 0.08 0.08 0.08 0.08 reach benefit Is there also a benefit upstream of yes yes yes yes yes no no no no no no yes yes yes the South Otway offtake?

Upper freshwater 0.00 0.04 0.06 0.08 0.06 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.06 0.08 reach benefit Combined benefit metric 0.00 5.08 9.13 10.16 9.13 9.13 10.08 9.06 11.08 5.04 9.06 10.08 14.12 16.14 18.16

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Appendix H: “Doing our bit to help the Gellibrand River”

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