Barwon Downs Borefield
Background and Submission
26 November 2018
1 Acknowledgements Traditional owner acknowledgement
Barwon Water acknowledges the traditional custodians of the land on which we live today. We pay our respect to their Elders past, present and future. We recognise and respect their culture, beliefs and ongoing connection to the land over thousands of years.
We would also like to give a special thanks to Kuuyang Maar, who have provided invaluable input and insight during the engagement process.
Barwon Downs Groundwater Community Reference Group acknowledgement
We would like to thank our Community Reference Group1 who have been actively involved in the Barwon Downs licence renewal project since 2013. Barwon Water greatly appreciates the dedication and insight each member contributed to this project.
As well as ensuring that the monitoring program captured and addressed key areas of community concern, the reference group also provided valuable support to Barwon Water during the broader engagement process with the local community.
Each community reference group member has dedicated a substantial amount of time and effort over the past five years for which we are very grateful. Through the process we have heard a diverse range of opinions, engaged in rich discussions and seen the project through the lens of the community.
Members of the community reference group we would like to thank are:
Jan Greig (Chair) Doug Chant Gavin Brien Robin Povey Malcolm Gardiner Hans Fankhanel Robert Maxwell Henry Bongers
Community workshop participants’ acknowledgement
We would like to thank all the participants who were involved in the 2017 Barwon Downs licence renewal community and stakeholder workshops for both their time, and their considered and thoughtful contributions. This input has enabled our application to address, where possible, many of the outcomes considered important to the community.
1 The Community Reference Group is an advisory group only. While they have provided their recommendations they have not been asked to endorse the final licence application.
2 Table of contents Acknowledgements ...... 2 Table of contents...... 3 How to navigate this document ...... 8 1 Setting the scene...... 9 1.1 Application to renew ...... 9 1.2 Dealing with the impacts of historic pumping ...... 10 1.3 Barwon Water at a glance ...... 11 1.4 Corporate obligations ...... 11 1.5 Why are we applying for a licence renewal? ...... 13 1.6 Geelong’s water resources ...... 14 1.7 How we plan to use the borefield going forward ...... 16 1.8 Background to the approach to the licence application (2012 – 2018) ...... 16 2 Overview of the Barwon Downs borefield ...... 17 2.1 Where is the borefield? ...... 17 2.2 History of the borefield and groundwater extraction ...... 18 2.3 Existing Gerangamete Groundwater Licence (No. BEE032496) ...... 18 3 Process for preparing the licence application ...... 20 4 Summary of supporting technical studies ...... 21 4.1 Stages 1 & 2: Monitoring program review and refinement ...... 24 4.2 Stage 3: Monitoring program implementation ...... 24 4.3 Stage 4: Technical studies – phase 1 ...... 25
3 4.4 Stage 5: Improving the conceptualisation ...... 30 4.5 Stage 6: Technical studies – phase 2 ...... 42 4.6 Stage 7: Licence application preparation ...... 45 5 Community Reference Group ...... 57 5.1 Checking in with the CRG ...... 57 5.2 Outcomes of the CRG ...... 58 5.3 Barwon Water response to CRG ...... 59 6 Broader consultation ...... 60 6.1 Community information sessions ...... 60 6.2 Community and stakeholder workshops ...... 60 7 Our commitments to the community ...... 62 7.1 Managing the ongoing operation of the borefield conservatively ...... 65 7.1.1 Barwon Downs Operational Plan ...... 65 7.1.2 Proposed Volumetric Entitlements ...... 65 7.2 Establishing an adaptive monitoring program ...... 67 7.2.1 Continued monitoring ...... 67 7.2.2 Proposed additional monitoring and triggers to protect environmental indicators ...... 67 7.2.3 Investigate Aquifer Storage and Recovery...... 67 7.3 Developing and implementing a remediation plan for Boundary Creek ...... 68 7.3.1 Develop and Implement Remediation Plan as outlined in the Section 78 Notice ...... 68 7.3.2 Boundary Creek stock pipeline operational ...... 68 7.3.3 Platypus study ...... 68 7.4 Building knowledge and trust in the science with the community...... 69
4 7.4.1 Submission of all technical work ...... 69 7.4.2 Implement citizen science program and establish database of shared information ...... 69 7.4.3 Publish all technical studies ...... 69 7.5 Interactive engagement with the community ...... 70 7.5.1 Establish the Barwon Downs working group ...... 70 7.5.2 Annual Information Sessions...... 70 7.5.3 Advise community of any changes ...... 70 8 Conclusion ...... 71 9 Supporting documents ...... 72 9.1 Appendix A – Criteria for the assessment under Water Act 1989 ...... 72 9.2 Groundwater Assessment report ...... 72 9.3 Other supporting documents ...... 72
5 Figures
Figure 1: Our service area ...... 12 Figure 2: Sustained dry climate reducing inflows into the West Barwon Reservoir ...... 15 Figure 3: Map of the Barwon Downs region including the aquifer extent and the groundwater recharge area...... 17 Figure 4: Chronology of the Barwon Downs borefield ...... 19 Figure 5: Licence renewal approach ...... 20 Figure 6: Inter-relationships of the monitoring program ...... 21 Figure 7: Stages of monitoring program and supporting technical studies ...... 23 Figure 8: Drilling of observation bore ...... 25 Figure 9: Sites used for study – TB8 (left) and TB1 (right) ...... 26 Figure 10: Boundary Creek assessment sites ...... 29 Figure 11: When the groundwater model was updated...... 32 Figure 12: Cross section of the Barwon Downs graben ...... 33 Figure 13: Boundary Creek ...... 35 Figure 14: Boundary Creek historic impact ...... 44 Figure 15: Community Workshop in Colac (September 2017) ...... 61 Figure 16: Our response to community inputs ...... 62
6 Tables
Table 1: Volumetric entitlements Barwon Water is applying for ...... 9 Table 2: Bulk entitlements for Geelong’s water resources ...... 14 Table 3: Outcomes of the Barwon Downs Technical Works Program – Integration Report (Jacobs, 2017) ...... 36 Table 4: Overview of modelling scenarios ...... 46 Table 5: Outcomes of the groundwater modelling ...... 46 Table 6: Outcomes of the risk assessment for environmental receptors across the study area ...... 48 Table 7: Outcomes of the risk assessment for environmental receptors in Boundary Creek catchment ...... 51 Table 8: Ecological condition (i.e. good, moderate, poor), management objectives (i.e. to maintain or improve), targeted physical and ecological outcomes and associated minimum low flow requirements for Boundary Creek...... 54 Table 9: Barwon Water’s proposed actions in response to the community’s nine key outcomes...... 63 Table 10: How Barwon Water’s actions will meet the nine community outcomes ...... 64 Table 11: Proposed volumetric entitlements ...... 66 Table 12: Register of supporting documents ...... 72
7 How to navigate this document
8 associated with this application for renewal, the Groundwater 1 Setting the scene Assessment Report and supporting technical studies should be considered. 1.1 Application to renew Barwon Region Water Corporation (Barwon Water) applies to renew The goal of this application is to ensure that the taking and use of the Groundwater Extraction Licence No. BEE032496 for the Barwon water under a renewal of this licence is consistent with the Downs borefield. The proposed use, source and volumetric sustainable use of the Barwon Downs Borefield as a part of a secure entitlements sought for the next 15-year period are tabled below. and affordable regional water supply for the long term.
Table 1: Volumetric entitlements Barwon Water is applying for
1. Type of use for which water is taken Urban Supply 2. Groundwater Management Area from which Gerangamete the water is to be taken 3. Maximum daily rate at which the water may 45ML be taken 4. Maximum volume of water that may be taken 12,000ML in any year (ending June 30) 5. Maximum volume of water that may be taken 60,000ML in any period of 15 years (ending June 30)
As part of this licence application, we have thoroughly considered those matters relevant under the Water Act 1989. Our assessment is set out in Appendix A, Criteria for assessment under the Water Act 1989.
To inform the technical resource assessment Barwon Water commissioned a Groundwater Assessment Report, which presents Barwon Water acknowledges that historic pumping and failures in the technical data and describes the approaches used to determine the effectiveness of some existing licence conditions have led to the potential impacts associated with future operation of the poor environmental outcomes for Boundary Creek and Big Swamp. Barwon Downs borefield. To understand the technical issues
9 Barwon Water’s decision to pursue this groundwater licence renewal This conclusion has been shared with the community and our was not taken lightly. We weighed up historic adverse impacts stakeholders. caused by groundwater pumping, technical studies that improved our understanding of potential future impacts, community concerns Throughout our consultation process, the community made it clear about the sustainability of extraction and the region’s ongoing need that they placed a high value on rehabilitating Boundary Creek and to access this critical resource. Big Swamp to improve stream flow and water quality, with the ultimate goal of returning the creek to a healthy, thriving Informed by an extensive technical program undertaken since 2012, ecosystem. Barwon Water is confident that, with the appropriate controls in place, we can rely upon the use from and availability of water from In response, we made a commitment to develop and implement a the Barwon Downs borefield for the benefit of our community remediation plan for Boundary Creek (refer to section 7.3). sustainably into the future. While remediation efforts are underway with the formation of the 1.2 Dealing with the impacts of historic pumping Boundary Creek remediation working group, the plan itself has now Recent technical work confirmed that Barwon Water’s pumping been given legal force by a ministerial notice issued under section from the Barwon Downs borefield over the past 30 years is the main 78 of the Water Act 1989. The section 78 Notice, is set out in the cause of a reduction in baseflow (groundwater contribution to documents attached to this application – see Table 12 for register. streamflow) in the lower reach of Boundary Creek increasing the frequency and duration of no flow periods. The dry climate In broad terms the section 78 Notice directs Barwon Water to: experienced in the same period and ineffective management discontinue extraction, other than for maintenance and measures were also contributing factors. emergency response purposes, while the assessment is being completed and until all remediation work required under the Lack of flow, especially during summer months caused: remediation plan has been completed. prepare and implement a remediation and environmental Big Swamp to dry out, protection plan for Boundary Creek, Big Swamp and The activation of naturally occurring acid sulfate soils in the surrounding area. swamp, and The release of acidic water (pH less than 4) downstream of the The purpose of the Notice is to ensure that Barwon Water swamp. successfully remediate impacts caused by historic groundwater
10 extraction for the Boundary Creek catchment. It is a commitment of people during the peak holiday periods. 92% of our customer base Barwon Water that – irrespective of the outcomes of this licence is residential, with the remaining 8% a mixture of commercial, application – the requirements of the section 78 will be met. industrial, and agricultural customers.
A clear distinction needs to be drawn between past impacts caused Our region by groundwater pumping and the future operation of the borefield. Our region of responsibility stretches over 8,100 square kilometers, from Little River and the Bellarine Peninsula in the east, to Colac in The section 78 Notice applies to the remediation of past impacts. the west, and from Meredith and Cressy in the north, to Apollo Bay On the other hand, this licence application is forward looking, and on Victoria’s south-west coast. Refer to Figure 1. proposes conditions to ensure that ongoing access to this resource is sustainable. This licence application contemplates that the 1.4 Corporate obligations substance of the requirements of the section 78 Notice, insofar as it Barwon Water provides essential services through the provision of deals with the taking and using of water, are embedded in any water and has an obligation to ensure that we operate as efficiently renewed licence. as possible consistent with sound commercial practice as per our Statement of Obligations. This application is built on the premise that the requirements of the section 78 notice will be met and that the notice will then be Our vision for an economically, socially and environmentally rescinded to allow production pumping to commence. We propose prosperous region is also incorporated into our statutory functions that this be included as a condition of the licence. which includes, to:
1.3 Barwon Water at a glance (a) provide, manage, operate and protect water supply systems, Barwon Water is Victoria’s largest regional urban water corporation. including the collection, storage, treatment, transfer and We support regional prosperity by providing excellence in water, distribution of water; and sewerage and recycled water services to our customers and the (b) identify community needs relating to water supply and to plan for community and have done so for more than 110 years. the future needs of the community relating to water supply.
Our customers This is embedded in our five-year Price Submission which will We deliver high-quality, affordable and reliable water services to deliver greater value to our customers by keeping bills affordable. more than 300,000 permanent residents – reaching up to 510,000
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Figure 1: Our service area
12 1.5 Why are we applying for a licence renewal? Barwon Water’s Urban Water Strategy (2017) describes how we will It is important to realise that these numbers do not reflect the continue to deliver secure water supplies to the region over the next volume Barwon Water expects to take each year from the borefield. 50 years, supporting resilient and liveable communities under a However, they do indicate the potential impact on water security range of climate scenarios. without access to this important resource.
Experts2 predict that Greater Geelong’s population could increase to The Urban Water Strategy (2017) identifies seawater desalination as 445,000 by 2040, leading to significant pressure on the region’s one of the likely options for the next major water source upgrade water supplies. for the region. Without access to the borefield, planning for a new water supply upgrade to replace this would need to begin To better understand the importance of the borefield, the Urban immediately, bringing this upgrade forward by 20 years and at an Water Strategy determined the yield of the system without the estimated net present cost of $210 million3. This cost would need to borefield under current climate and demand, and again in 2065 be funded by Barwon Water customers and would result in under conditions of high climate change and population growth to significant price rises with potential to create financial strain. demonstrate the impact on system yield if this resource is no longer available. Although in the short term (while the section 78 Notice is in place), Barwon Water can prioritise the use of our other back up sources Without access to the borefield, the yield of the Greater Geelong such as the Melbourne to Geelong pipeline and the Anglesea and Colac system would be reduced by 11,000ML/year, equivalent borefield, towards the end of the next licencing period (2019-2034) to 20% of the current yield. By 2065 under a high climate change access to water from the Barwon Downs borefield is required to and high population growth scenario - when runoff is forecast to be provide security to the region under certain climate conditions. almost 50% lower than that under current climate change – the impact of not having the groundwater resource becomes even more Even with our other back up sources at full capacity (Melbourne to significant, with a reduction in yield of more than 14,000ML/year, or Geelong Pipeline and the Anglesea borefield) this won’t be enough more than 30%. to ensure the region’s water security in the next 15 years.
2 Victoria in Future (2016) Population and household projections to 2051 3 Barwon Water (2018) Economic cost analysis for the 2019 Barwon Downs licence renewal. Analysis is based on current, not proposed, licence volumes.
13 Maintaining access to the Barwon Downs borefield also provides During this time, the only available back up source was Barwon greater resilience to our water supply system in the event of Downs. It was used very heavily during this period, at times unexpected growth or climate extremes. This is important so we can supplying above 70% of Geelong’s daily water requirements. continue providing an essential service and liveability outcomes by Without the use of the borefield during this time, Geelong would providing drinking water, irrigating sporting ovals and public have, almost certainly, run out of reticulated water. gardens, supporting business and economic expansion and looking after our catchment and waterways. Since then large scale projects like the Melbourne to Geelong Pipeline and the Anglesea borefield have been implemented to It also provides security against unplanned events such as major diversify and increase our water resources to be more resilient to infrastructure failures or natural disasters like bushfire. Any access to climate variability. Barwon Water now has three back up sources the borefield will be in line with the restrictions placed under the available, including the Barwon Downs borefield. section 78 Notice. Access to water resources in the Geelong system is enshrined in 1.6 Geelong’s water resources bulk entitlements and licences summarised in Table 2. Barwon Water predominately relies on catchments on the upper Barwon and Moorabool rivers to supply our customers with high- Table 2: Bulk entitlements for Geelong’s water resources quality and affordable drinking water. Bulk entitlement Volume Barwon 130,400 ML over 3 years During times of drought and low inflows, we call on our back up 6,000 ML over 3 years at She Oaks West Moorabool sources - underground aquifers at Anglesea and Barwon Downs and 17,775 ML over 3 years at Lal Lal we can also access the Victorian water grid via the Melbourne to East Moorabool 9,000 ML/year Geelong pipeline. During drought, Colac can be connected to the Barwon Downs borefield Up to 20,000 ML/year Geelong supply system via the Wurdee Boluc channel near Muroon. Anglesea borefield 7,000 ML/year
Greater Yarra System – 16,000 ML/year Between 1997 and 2010, the region and broader state experienced Thomson River Pool what has since been referred to as the Millennium Drought. During Average annual total Up to 103,392 ML/year this time, the Geelong region was placed on Stage 4 water restrictions to curb demand and had sustained low inflows (see Figure 2) leading to precariously declining storages.
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Figure 2: Sustained dry climate reducing inflows into the West Barwon Reservoir
15 1.7 How we plan to use the borefield going Therefore, the presence of the Barwon Downs borefield as an forward available water reserve is vitally significant, regardless of Climate conditions and surface water stream flows are naturally whether that reserve is actually called on. variable. The proposed groundwater licence provides the legal 1.8 Background to the approach to the licence certainty of being entitled to access groundwater from the application (2012 – 2018) Barwon Downs borefield up to the volumetric limits proposed The licence application has been developed over the past six should it be required if climate conditions require surface water years utilising three key inputs: supplies to be supplemented. A comprehensive scientific monitoring program and Without the certainty of being able to access groundwater in supporting technical studies; the long term, an investment in additional water resources (e.g. A Community Reference Group (CRG) that provided seawater desalination) would be required to provide an guidance and input throughout the entire process, and equivalent level of certainty of access to water to supplement Wider consultation with the community and our surface water sources in dry climate conditions. stakeholders to ensure our application incorporates Surface water sources would be used as the first preference outcomes important to them. source (within the constraints permitted in Bulk Entitlements to this water) as these are the lowest cost sources of water available to Barwon Water.
The backup water sources such as Barwon Downs borefield would be called on in dry periods when water storage levels decline. Operation of the backup water sources in dry climate conditions is required to ensure that Barwon Water’s customer service level for water security can be met as defined in the Urban Water Strategy (2017).
The local water storage level trigger for activating standby water sources is adjusted and optimised from time to time to ensure continued ability to meet the service level for water security, allowing for growth in demand and climate change. 16 2 Overview of the Barwon Downs borefield 2.1 Where is the borefield? The Barwon Downs borefield is located approximately 70 km south west of Geelong and 30 km south east of Colac (refer to Figure 3).
The surrounding land is a mixture of agricultural use and state forest. A substantial proportion of the catchment area has been farmed for over a century with some parts of the landscape being highly modified compared to the surrounding natural environment.
The regional groundwater system extends beneath two surface water catchments, the Barwon River catchment and the Otway Coast catchment.
The Barwon River and its tributaries rise in the Otway Ranges and flow north through Forrest and Birregurra. The Barwon River West Branch and East Branch drain the southern half of the catchment and come together just upstream of the confluence with Boundary Creek. Boundary Creek flows east across the Barongarook High and joins the Barwon River around Yeodene.
The Otway Coast catchment is a large catchment with many rivers that flow towards the coast. The Gellibrand River is in the Figure 3: Map of the Barwon Downs region including the aquifer extent and the largest of these rivers and rises near Upper Gellibrand and flows in a groundwater recharge area. westerly direction towards Gellibrand. The Gellibrand River discharges to the ocean at Princetown.
17 The borefield taps into an underground source of water, known as maximum volume of water that may be taken in any period of 100 the Lower Tertiary Aquifer (LTA), with depths of up to 600 metres at years according to the current licence conditions (400,000ML). the borefield. The aquifer covers an area of approximately 500 km2 The borefield has been a critical standby source for Barwon Water below the surface and is connected to the surface in both the Barwon because it is buffered from climate variability due to the depth and River catchment (Barongarook High) and the Otways Coast substantial volume of the aquifer, whereas surface water catchments catchment near Gellibrand. are susceptible to seasonal fill patterns mostly driven by rainfall. 2.2 History of the borefield and groundwater extraction 2.3 Existing Gerangamete Groundwater Licence (No. Investigations into groundwater resources first commenced in 1967 and revealed a significant resource in the Barwon Downs region. After BEE032496) a decade of drilling test production bores, four production bores The Barwon Downs borefield is currently operated under licence from were constructed at Barwon Downs in 1982. Southern Rural Water who administers and regulates groundwater licences on behalf of the state’s Minister for Water. Reporting against Although extraction has occurred relatively infrequently over the last these licence conditions is currently provided in an annual report. 35+ years, large amounts of groundwater have been drawn when needed in accordance with licences issued by Southern Rural Water. The licence contains volumetric limits, groundwater level triggers, compensatory flow release requirements for Boundary Creek and The history of the borefield is depicted in Figure 4. monitoring of groundwater levels, water quality, riparian vegetation, subsidence and flows in the Barwon River and its tributaries. To date, Barwon Water has extracted the following volumes from the aquifer:
3,652 ML from February to April in 1983 due to drought; 19,074 ML during a long term pump test in the late 1980s; 36,817 ML during the 1997 - 2001 drought; 52,684 ML during the 2006 – 2010 millennium drought, and 3,449 ML in 2016 to boost storages after a record dry summer.
Groundwater extraction has supplemented surface water supply by a total of 115,676 ML equating to approximately 30 per cent of the
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History of Barwon Downs
Figure 4: Chronology of the Barwon Downs borefield
19 3 Process for preparing the licence application
Ahead of this licence renewal application, Barwon Water instigated: an enhanced monitoring program through the construction of new monitoring assets; undertook wide ranging technical studies, and engaged with the CRG and the broader community to inform the licence application (refer to Figure 5).
A summary of the scope and outcomes of the technical work program can be found in Section 4, and detailed in the groundwater assessment report and supporting technical reports.
A summary of the role and contribution of the CRG is provided in Section 5.
A summary of the broader consultation undertaken by Barwon Water to inform the application is provided in Section6. Figure 5: Licence renewal approach
20 4 Summary of supporting technical studies Barwon Water initiated a new monitoring program and supporting technical studies – developed with a range of experts and using multiple lines of evidence – to inform this licence renewal process. The monitoring program continues to collect data to this day and we propose that it will continue as a licence renewal condition.
The aims of the monitoring program were to:
Better understand the historical environmental impacts of groundwater extraction to inform the application for future use; Determine the cause and relative contribution of groundwater extraction in contributing to historic environmental impacts, and Provide additional monitoring data and subsequent analysis required to inform the licence renewal application.
The monitoring program established, as shown in Figure 6 was complex and multi-disciplinary - acknowledging the connectivity between groundwater and receptors at the surface - with many interrelated components in the disciplines of groundwater, surface water, aquatic groundwater dependent ecosystems, terrestrial groundwater dependent ecosystems and potential acid sulfate soils.
Figure 6: Inter-relationships of the monitoring program
21 A review of the licence and supporting monitoring program was The monitoring program was designed, in collaboration with the initiated in 2012, focusing strongly on what could be done to address CRG, to differentiate between groundwater extraction and climate technical and environmental gaps. effects on the groundwater system, predict water table and stream flow changes, and increase the understanding of ecological impacts. It was started early to allow enough time to establish a comprehensive monitoring program and collect data to resolve gaps. Each monitoring activity and technical study was presented to the CRG for input and adjusted to target community concerns. For The review highlighted that while groundwater processes were example, selection of vegetation and acid sulfate soils sites for understood sufficiently to enable reliable estimates of groundwater ongoing monitoring were based on specific input from the CRG. Each availability for pumping, there wasn’t enough data to understand discipline and associated monitoring activities were endorsed by the impacts at the surface to environmental indicators relying on CRG before the scope of the monitoring program was finalised. groundwater. Each technical study is captured below in Figure 7. There wasn’t the same degree of confidence in the processes and subsequent impacts to the accuracy required for environmental The monitoring program and supporting technical studies have assessments to be carried out (related to the extraction of large significantly improved our understanding of the groundwater system volumes of groundwater) for the: and informed the update of the groundwater model. drying of potential acid sulfate soils, decline in stream flow and flow on impacts to aquatic flora and All work completed was integrated to present a strengthened fauna reliant on groundwater, conceptual understanding through a significant update of the changes to groundwater water quality, and the groundwater model to better understand how the Barwon Downs stress on terrestrial flora and fauna. system operates.
Following the initial review of the licence and the formation of a CRG In accordance with the Australian Groundwater Guidelines, the in 2013, Barwon Water refined the scope of the new monitoring model has been determined to have a Class 3 Confidence Level program to ensure that it targeted both key areas of community Classification which is consistent with the modelling objectives and concern and technical gaps. with the high value of the environmental and economic assets at risk.
22 The groundwater model was also able to confirm that historic pumping, a dry climate and ineffective management measures had unacceptable impacts in the Boundary Creek catchment. We now know a lot more about the Barwon Downs groundwater system than we previously did because of the monitoring program and the technical studies. While we are now more confident in the science supporting this application, we are committed to building on this knowledge base during the next licencing period to continually improve our scientific understanding of this complex system.
Figure 7: Stages of monitoring program and supporting technical studies
23 4.1 Stages 1 & 2: Monitoring program review and The proposed scope was progressively presented to the CRG and refinement refined based on input to ensure that community concerns were targeted. For example, vegetation and acid sulfate soils sites for
ongoing monitoring were relocated based on recommendations Report title: Barwon Downs monitoring program – review from the CRG. The revised monitoring program and supporting (SKM, 2012) technical studies were endorsed by the CRG before the scope was finalised. Scope Outcome The desktop review identified existing knowledge gaps and New monitoring activities and supporting technical studies would suggested technical improvements that could be made to advance improve technical gaps to be able to predict impacts to address the understanding of the groundwater system. community concerns. Outcome 4.2 Stage 3: Monitoring program implementation Using a risk assessment process, scope for additional monitoring activities and supporting technical studies were recommended to Report: Field investigations report – installation of new address technical knowledge gaps and known community issues to monitoring assets (Jacobs, 2016) improve the reliability of predicting impacts to environmental Scope indicators to inform the 2019 licence renewal application. This report documents the capital works program to install new bores and reinstate existing bores. Report title: Barwon Downs monitoring program – stage 1: field Outcome investigations and monitoring program scope (SKM, 2013) During 2014-15, a field program delivered the majority of installation or reinstatement of 40 observation bores, which Scope included: This report outlines the monitoring program scope including 35 new monitoring bores were drilled and constructed, specifications, design work and estimated costs for new monitoring Two existing bores were replaced, assets and technical studies to improve the capacity to differentiate Three bores were reinstated by airlifting and fixing bore head between groundwater pumping and climate effects on the works, groundwater system, predict water table and stream flow changes Data loggers were installed to monitor groundwater levels in all where the aquifer is unconfined and better understand ecological bores, impacts directly related to groundwater extraction
24 Gamma logging was undertaken on all new bores and 12 4.3 Stage 4: Technical studies – phase 1 existing bores to collect information on the presence of Report title: Barwon Downs vegetation monitoring – vegetation confining clay layers in the hydrogeological profile, monitoring report (Jacobs, 2015) Hydraulic testing, in the form of slug tests, was undertaken on 30 bores to understand the range of aquifer parameters in each Previous flora studies completed in the 2000s weren’t able to formation, and separate the influences of catchment activities, climate conditions Groundwater samples were analysed for salinity and pH and and pumping on groundwater dependent vegetation. some aquitard bores were analysed for major ions.
The extent of some formations and aquifer parameters such as The 2012 review exposed the limitations of existing vegetation sites hydraulic conductivity and water quality were able to be refined to and recommended that a comprehensive flora monitoring regime support the update of the groundwater model. be established (also stated in the 2008-09 flora study).
In 2013, a desktop assessment and subsequent fieldwork which considered more up to date hydrogeological data enabled the selection of 14 new vegetation sites (which incorporated three existing sites). The intent was to improve the understanding of the link between vegetation and groundwater dependence, and if extraction from the borefield contributed to fluctuations in water table depth at these sites.
In 2014, Southern Rural Water approved Barwon Water’s request to amend the vegetation sites outlined in Clause 7 of the groundwater licence.
Scope Figure 8: Drilling of observation bore To undertake the five-yearly vegetation assessment survey (flora study) as stipulated under the groundwater licence. The new vegetation sites were used for this survey because of their
25 hydrological sensitivity making them more likely to be dependent on groundwater
Outcomes The 14 new vegetation sites enabled a baseline to be re-established founded on statistically robust comparisons so that detection and quantification of changes in the performance of groundwater dependent species over time, as well as between reference and impact sites based on the underlying hydrogeology can be made.
Importantly, when comparing the impact (within areas of the aquifer where the water table was either known to have been affected from past pumping or has the potential to be affected by future pumping) and reference sites (where no impact has been or is expected to be observed in water levels in the aquifer), there was no difference in the health of groundwater dependent vegetation, Figure 9: Sites used for study – TB8 (left) and TB1 (right) regardless of the underlying hydrogeology. Report title: Barwon Downs groundwater dependent terrestrial
vegetation investigations – understanding tree water use Differences in vegetation conditions will continue to be measured (Jacobs, 2016) over time and sites compared based on their underlying In late 2015, a study was completed to determine whether terrestrial hydrogeology and capacity to be influenced by any groundwater vegetation was using groundwater (and to what extent) and to extraction from the borefield. assess whether there was any evidence of impact from historical groundwater pumping on vegetation condition.
Scope This study focused on groundwater use by deep rooted trees rather than shallow rooted shrubs, sedges or grasses. Deep rooted plants can utilise groundwater at great depth, hence the potential
groundwater dependence of this vegetation type covers a much larger portion of the study area.
26 The objectives of this investigation were to: While groundwater pressures in the pumped aquifer have declined determine whether terrestrial vegetation in the study area is in the aquifer outcrop area near the borefield, this study determined using groundwater; and, that trees using groundwater had not been adversely affected by assess whether there is any evidence of impact from historical declining groundwater levels. This was likely due to the presence of groundwater pumping on the condition of vegetation that is perched aquifers, hydraulic buffering between shallower and deeper determined to be using groundwater. units within the aquifer and the ability of trees to adapt to changing
water levels. The project involved a field program and analysis of remote sensing data known as Normalised Difference Vegetation Index (NDVI). This study recommended ongoing monitoring of vegetation
through an annual flora survey when the borefield is in operation NDVI analysis suggested that vegetation used groundwater during and a review of the NDVI data after each period of borefield use to periods of low water availability, as there was higher NDVI where monitor potential changes in the regional vegetation condition that the water table is shallow, compared to where the water table was is not possible in the site by site assessment. deep. Conversely, this trend was not observed in periods of relative water availability. Report title: Barwon Downs vegetation survey report (Jacobs,
2017) The field program supported the hypothesis of groundwater use by The timing of this vegetation survey was brought forward knowing trees and was also consistent with the conclusions from the NDVI that the borefield would be pumped given the record dry summer analysis. of 2016.
Outcomes Scope There was no evidence that groundwater extraction from the Another vegetation survey was completed for the 14 sites to collect Barwon Downs borefield had a negative impact on vegetation adequate baseline information on the vegetation’s response and activity or condition, as measured by NDVI. This was based on resilience to the recent below average rainfall conditions, without assessment of areas of shallow groundwater, where groundwater the influence of groundwater extraction from the Barwon Downs use was more likely, and on vegetation across the area in general. borefield. There is no difference observed across time in vegetation closer to the borefield (where greater levels of drawdown in the aquifer have occurred) versus further away.
27 Outcomes Scope This vegetation assessment survey noted that there was a consistent The objective was to estimate the aquatic flora and fauna species decline in vegetation across the monitored sites due to the drying and communities supported by Boundary Creek in the present day – of the catchment, rather than from borefield use (note that the not historically – and at a broad scale (i.e. qualitatively), discuss the borefield was not in operation when the survey was conducted). elements of the creek’s flow regime that these values require.
This was not surprising given that south-west Victoria had To do this, a combination of direct survey and indirect assessment experienced below average rainfall conditions over the last 18 techniques were used. Macroinvertebrates were surveyed directly in months. Although the link between groundwater and vegetation the spring and autumn of 2015. The vegetation, fish, frogs and present is highly variable and localised, all sites were considered to platypus species and communities supported by Boundary Creek be groundwater dependent to some extent and vegetation were estimated by considering historic records, other literature and condition was likely to continue to decline if rainfall remained below the current habitat present at the creek. average as groundwater levels will decline (naturally) in low rainfall periods. Outcomes The Boundary Creek catchment has experienced significant changes There were no noticeable differences between impact/reference since European settlement some of which have permanently altered sites and confined/unconfined sites. Overall vegetation species the flow regime of the creek. Changes include channelisation, abundance had not changed markedly since the last survey. The construction of ‘McDonalds Dam’, farm dams, private diverters, survey highlighted the ecosystem’s response to natural climate groundwater extraction, supplementary flow release, drought and variability. the drying, trenching and acidification of Big Swamp.
This report reaffirmed that vegetation monitoring should continue. Key hydrological features that have shaped the ecological values of the creek were the: Report: Boundary Creek aquatic ecology investigation (Jacobs, Supplementary flow that made up a significant portion of the 2017) flow in the summer months in Reach 1 and 2 (upstream of Big In late 2014, the hydrology and aquatic ecology components of the Swamp). monitoring program began. Flow was evident in the stream until Big Swamp, but was not apparent downstream under many conditions. Boundary Creek
28 in Reach 3 (downstream of Big Swamp) rarely stopped flowing The influence of Big Swamp on the hydrology of Reach 3 of at any time of year prior to 1999, but since then has stopped Boundary Creek was likely to be significant, however, the flowing for long periods in most summer and autumn months complexity of the groundwater-surface water interactions, soil downstream of Big Swamp. chemistry and management history meant that investigating this The water in Reach 3 of Boundary Creek was (and continues to influence was beyond the scope of this study. be) highly acidic. Big Swamp was the focus of a future, stand-alone study.
Figure 10: Boundary Creek assessment sites
29 The ecological values currently supported by Boundary Creek are (although some frogs may use some habitat in the reach). The summarised below. macroinvertebrate community is in poor condition (AUSRIVAS Band C). In Reach 1 (from the top of the catchment to the downstream end of “McDonalds Dam”) the majority of the riparian zone is made up 4.4 Stage 5: Improving the conceptualisation of an overstorey of Eucalyptus and Acacia, with a ground layer of An improved understanding of the conceptual model allows for a weeds and occasional sedges and herbs. The channel supports more rigorous assessment and management of the groundwater Water Ribbons. Some fish species are likely to be present including response resulting from borefield pumping. Five key knowledge Short-finned Eels, Flathead Gudgeon and Mountain Galaxias. The areas for improvement were identified: macroinvertebrate community is in excellent condition (AUSRIVAS Band A) and a range of common and widespread frog species are 1. Groundwater levels at terrestrial vegetation monitoring sites to likely to be supported. understand the relationship between vegetation and groundwater at vegetation monitoring sites and evaluate Reach 2 contains a ‘dampland’ with a dense canopy of Melaleuca potential drawdown impacts on vegetation where the LTA is squarrosa and Leptospermum lanigerum and a wetland ground-layer confined and unconfined. of diverse sedges, rushes and reeds that are likely reliant on 2. Groundwater levels and aquifer parameters, particularly in the permanently waterlogged soils. The riparian vegetation upstream of MTD to understand levels, vertical gradients, hydraulic the ‘dampland’ has been largely cleared for agriculture. Yeodene properties, flow directions and fluctuations in groundwater Swamp (which was outside the scope of this study) is located at the levels to help understand impacts of pumping on the aquitard downstream extent of Reach 2. The water in the channel in Reach 2 and overlying ecological values. is usually shallow and is therefore unlikely to be suitable for large 3. Groundwater surface water interactions along drainage lines bodied fish species, although Flathead Gudgeon and Southern (e.g. Boundary Creek, Dividing Creek, Ten Mile Creek and minor Pygmy Perch may be present in addition to Eels and Mountain tributaries) and surface water levels in Boundary Creek to Galaxias. The macroinvertebrate community in Reach 2 was improve the understanding of groundwater surface water assessed as being significantly impaired (AUSRIVAS Band B). interactions. 4. Groundwater levels in the water table aquifer at Barongarook Reach 3 dries in most summers, typically has highly acidic water High (including bedrock and LTA). when it is flowing and has limited aquatic habitat due to the cleared 5. Groundwater levels at sites with potential acid sulfate soils riparian zone. It is unlikely to support many resident aquatic species (PASS).
30 Some of the knowledge gaps seek to address physical gaps in the consistent with the Australian Groundwater Modelling Guidelines program (e.g. new bores or stream gauges provide levels or flow at (Barnett et al, 2012). a particular location). However, there is a different type of knowledge gap relating to how the system behaves overall. Firstly, In 2001, SKM (now Jacobs) carried out an extensive groundwater in the ‘historical’ state and then under various new changes (e.g. modelling study, to inform Barwon Water’s groundwater licence drought, land use change, groundwater pumping etc.). application. This resulted in the development and calibration of a large three dimensional groundwater model of the Barwon Downs Hydrogeologists refer to this ‘big picture’ as the “conceptual model” Graben (SKM, 2001). The model was calibrated by matching of the groundwater system. New data can either confirm the predicted groundwater levels to observed levels in a set of 24 existing conceptual model, or it can add new understanding/ monitoring bores spread throughout the Graben. The model was complexity or it can change the existing model (i.e. where prior then run for four different extraction scenarios to establish the understanding is seen as unsuitable). A conceptual model becomes sustainable yield by determining the impact of pumping on the common understanding on which predictive tools such as the groundwater levels. groundwater model are based on to estimate changes to the groundwater system. The groundwater model was again updated in 2006 to determine appropriate trigger levels in the licence conditions and to pinpoint The conceptual model is important in ensuring the computer model locations for the two new production bores. The work included re- (also referred to as a numerical model) is an accurate representation calibration of the groundwater model by comparing model of the real world and is useful in indicating how the groundwater estimates to observed groundwater behaviour over the period 1979 system will respond to changes such as groundwater extraction. (It to 2006 (SKM, 2007). is important to note that these findings do not mean that previous versions of the computer (numerical) model were not ‘correct’, only The model was again re-calibrated in 2011 to understand the that improvements will increase the confidence in areas of interest). potential impacts of future climate change on the groundwater resources of the Graben (SKM, 2011). Groundwater modelling for Barwon Downs has occurred since the 1990s (Witebsky et al, 1995; Teng, 1996). Progressive improvements of the groundwater model have been made since – an approach
31
Figure 11: When the groundwater model was updated
32
In 2016-17, the model was expanded, re-built and re-calibrated to inform this licence renewal. The update of the model includes new features and a significant improvement in the conceptual understanding. The revised groundwater model has a much broader focus than previous work that had concentrated primarily on undertaking a resource assessment to determine the availability of groundwater.
The model was determined to have a Class 3 Confidence Level Classification which is consistent with the modelling objectives and with the high value of the environmental and economic assets at risk. It is considered to be fit-for-purpose for on-going use to assess future groundwater behaviour and impacts that may occur from borefield operations.
The modelling has been undertaken in a manner that has allowed the distinction between impacts that have arisen as a result of borefield operations, the effectiveness of management measures and those arising from natural climate variability.
The calibrated model can: simulate impacts that would have happened naturally because of climate against impacts caused by groundwater pumping over the past 30 years, and
Assess likely impacts over the next 50 years due to groundwater pumping. Figure 12: Cross section of the Barwon Downs graben
33 Report title: Barwon Downs monitoring program – review of A comparison of pre and post pumping groundwater levels conceptual model and numerical model boundaries (Jacobs, indicated that the groundwater divide between the Barwon and the 2015) Gellibrand groundwater catchments shifted during pumping. This was considered normal because groundwater divides move Scope naturally due to influences such as seasonal changes and long term The key driver for this study was to review the hydrogeological recharge rates, and are not fixed like surface water catchment conceptual model in light of new information and aquifer responses divides. to pumping. This review also examined the existing data along the edges of the study area to identify any significant limitations in the This comparison also confirmed the existence of a hydraulic barrier hydrogeological conceptual understanding of these boundaries. restricting the flow of groundwater between the two groundwater catchments. This indicated that pumping from the borefield would The boundaries were: have minimal impact to flows in the Gellibrand River. South west boundary – the area between the Barwon Downs and Gellibrand groundwater sub-basins, and This study made recommendations to improve the geological layers Northern boundary – Birregurra and Colac faults, and postulated and expand the model boundaries (especially faults) to inform the Barongarook Creek Fault. update and recalibration of the Barwon Downs groundwater model.
Outcomes Report title: Barwon Downs hydrogeological studies 2015/16 – Boundaries in a groundwater model influence the extent of recharge rate assessment (Jacobs, 2016) drawdown caused by groundwater pumping and control how the model allows water into or out of the system. Scope The objective of this study was to provide estimated rates of A review of the Newlingrook model highlighted that the aquifer recharge to the Lower Tertiary Aquifer in the Barwon Downs region thickness and extent was a more accurate representation and using a range of independent techniques to estimate actual therefore, a logical starting place to rebuild the Barwon Downs recharge rates to improve the accuracy and confidence in the groundwater model layers to improve the understanding of any numerical model. impacts to the water table, as well as the possibility of activating acid sulfate soils.
34 Outcomes relationship between groundwater pumping and how pumping may The results suggest that that best representation of current/modern impact groundwater indicators in the catchment. The outcomes are recharge to the LTA on the Barongarook High are derived from the presented in Table 3. application of the independent and interface methods. This suggests that modern recharge rates are most likely to be around 9 to 11% of the average annual rainfall in the area of aquifer outcrop.
Recharge to the Barongarook High is approximately 10% of average rainfall and unlikely to exceed 14% of average rainfall. These are the recommended rates to use as a starting point to inform the calibration process of the Barwon Downs groundwater model.
The recharge rates in this study were used as a starting point for the calibration of the groundwater model and further refined. Please refer to the Predictive Scenarios Modelling report (Jacobs, 2018) for the recharge rate used.
Report title: Barwon Downs Technical Works Program – Integration Report (Jacobs, 2017) Individual studies have been completed since 2012 to advance the understanding in five key areas groundwater, surface water, aquatic groundwater dependent ecosystems, terrestrial groundwater dependent ecosystems and potential acid sulfate soils.
Scope The intent of this report was to document improvements in the conceptual understanding of the hydrogeology in the Barwon Figure 13: Boundary Creek Downs region, particularly to improve the knowledge of the
35 Table 3: Outcomes of the Barwon Downs Technical Works Program – Integration Report (Jacobs, 2017)
Environmental Indicator / Outcomes Discipline A sound baseline monitoring network has been established that can confidently assess changes in groundwater levels which influences groundwater surface water interactions and streamflow, aquatic groundwater dependent ecosystems, terrestrial groundwater dependent ecosystems and potential acid sulfate soils. There is strong basis to understand historic pumping impacts and to predict future impacts to environmental indicators.
Groundwater Local perched alluvial aquifers in some parts of the catchment are recharged from rainfall and surface water and are independent of the LTA.
Drawdown from pumping at Barwon Downs borefield is more pronounced in the lower LTA compared to the upper LTA. Drawdown is buffered through the unit due to layering in the aquifer which protects the upper LTA and alluvial aquifers from groundwater level declines caused by pumping. A sound baseline monitoring network has been established that can confidently assess fluctuations in stream flow and inform the conceptualisation of groundwater surface water interactions in the Boundary Creek catchment.
Supplementary flow makes up a significant portion of the flow in the upper reaches of the creek during summer and autumn. Boundary Creek catchment Throughout the summer months, there is flow upstream of Yeodene (Big) Swamp, but rarely downstream of the swamp (at the Yeodene gauge on Colac-Forrest Road), making the effect of the swamp on flow hard to determine.
Creek flow regime has changed over time. Boundary Creek rarely stopped flowing during summer months prior to 1999, but since then has stopped flowing for varying periods each summer. Various factors
36 Environmental Indicator / Outcomes Discipline contributing to these ongoing cease of flows events have yet to be untangled and will be the focus of more technical works in 2017.
Water downstream of Yeodene (Big) Swamp is highly acidic.
Sound understanding established of existing ecological values in Boundary Creek and qualitative flow requirements.
Reach 1 (upstream of McDonalds Dam) has been artificially enhanced by the supplementary flow and current ecological values are good. Macro invertebrate communities are in excellent condition and the channel supports Short-finned Eels, Flathead Gudgeon, and Mountain Galaxias. A range of common and widespread frog species is likely to be supported.
Reach 2 includes the ‘dampland’ area downstream of McDonalds Dam and upstream of Yeodene (Big) Swamp and Yeodene (Big) Swamp itself. The water in the channel is usually shallow and unlikely to be suitable for fish. The macro invertebrate communities are significantly impaired (AUSRIVAS Band B) but the reach likely supports the Otway Bush Yabby and the assemblage of common frogs.
Reach 3 (downstream of Yeodene (Big) Swamp) dries frequently in summer, has highly acidic water when it is flowing and has limited aquatic habitat. The macro invertebrate community is in poor condition (AUSRIVAS Band C).
37 Environmental Indicator / Outcomes Discipline Gellibrand River is connected to the LTA and is a key discharge area for the aquifer. Most of the tributaries flow over the MTD, and springs from the MTD provide baseflow to some of the creeks. The MTD protects (buffers) the tributaries from drawdown in the LTA.
Drawdown from pumping at the Barwon Downs borefield does not appear to have affected the Gellibrand Gellibrand River catchment River to date due to the effect of a hydraulic restriction (geological barrier) within the aquifer between the Barwon and Gellibrand catchments
Additional stream-flow gauges are recommended on Ten Mile and Porcupine Creeks as a measure to ensure there is sufficient baseline information to assess potential future impacts although these are expected to be small. Baseline monitoring network established at 14 sites to monitor the relationship between vegetation health and groundwater pumping with no changes due to operation of the borefield detected to date. Monitoring was undertaken in 2014/15 and 2016.
2016 vegetation survey showed declines in vegetation health, in response to below average rainfall conditions. Given the borefield had not operated between 2010 and mid 2016 the results of this survey highlight vegetation’s response to natural climate variability. Vegetation
Groundwater monitoring bores are located at all the vegetation monitoring sites and although the link between groundwater and vegetation present was concluded to be highly variable and localised, all sites are considered to be groundwater dependent to some extent.
Additional work showed that deep rooted vegetation at most sites was found to rely on a groundwater during times of drought and where the watertable is shallow. No evidence was found that declining
38 Environmental Indicator / Outcomes Discipline groundwater levels caused by groundwater extraction at Barwon Downs had a negative impact on vegetation health in the catchment. Natural PASS exists across the study area.
Review of potential ASS sites in the region was completed and a sound baseline monitoring network established with 4 priority sites selected for ongoing monitoring. Monitoring was undertaken in 2015 and 2016.
Changes noted in ground conditions, surface water and groundwater were consistent with seasonal fluctuations.
Potential Acid Sulfate Soils Groundwater quality did not change over the monitoring period.
Groundwater levels are typically shallow (within 1 m below the surface) and display seasonal fluctuations of around 0.5 m, rising during the winter months and declining during the summer months.
Changes in surface water salinity were consistent with seasonal fluctuations, e.g. higher salinity during summer months when evaporation is higher.
No ASS issues outside of Yeodene (Big) Swamp were identified that would influence the upcoming licence renewal. No issues were identified relating to land subsidence that would influence the upcoming licence renewal. Land subsidence Recommendation to investigate potential to decrease monitoring frequency. Updated model builds on earlier model versions that can be used with confidence to assess future impacts Groundwater model associated with groundwater extraction from the Barwon Downs borefield.
39 Environmental Indicator / Outcomes Discipline The model includes features and characteristics of a Class 3 Confidence Level Classification model as defined by the Australian Groundwater Modelling Guidelines (Barnett et al., 2012). This is the highest confidence level classification in the guidelines and reflects the amount and quality of groundwater data used to conceptualise and calibrate the model.
Report title: Numerical model calibration and historical impacts improve the existing groundwater model ability to assess future (Jacobs, 2018) impacts related to groundwater pumping from the Barwon Downs borefield, and Scope develop a tool to simulate impacts that would have happened To update the existing Barwon Downs groundwater model based on naturally due to climate influences against impacts caused by additional data and information collected as part of a broader groundwater pumping over the past 30 years. investigation and monitoring program. These improvements Outcomes increased the confidence in the model’s predictive capabilities. The groundwater model is a Class 3 confidence level classification
and is considered to be fit-for-purpose for to assess future The calibrated model was used to determine the historical impact of groundwater behaviour and impacts that may occur from the borefield, including drawdown and changes to the surface water groundwater extraction. groundwater interaction at Boundary Creek and other rivers. Improvements made to the model produced a more reliable The model simulated historical impacts by separating groundwater representation of the groundwater system at both the regional and extraction from natural climate fluctuations. local scale. Significant effort was made to improve the model for the Boundary Creek catchment due to the complex hydrogeology and The objectives of developing an updated groundwater model were groundwater surface interaction in that area. to:
40 Modelling confirmed that operation of the borefield, including ineffective management measures, were the main cause of reduction in streamflow in Boundary Creek and was responsible for two thirds of the reduction of base flow into Boundary Creek. The dry climate experienced during the same period accounts for the remaining third.
This suggested that the lower sections of Boundary Creek would likely have no flow periods during summer regardless of groundwater pumping, however pumping increased the frequency and duration of no flow periods in the lower reaches of Boundary Creek.
No other rivers or creeks were impacted as significantly as Boundary Creek by the operation of the borefield.
Operation of the borefield resulted in a minor reduction in base flow in a small section of the Gellibrand River. Dry climate conditions have caused a greater reduction in base flow than the historical impact of the borefield.
Shallow aquifers across most of the study area have not been significantly influenced by operation of the bore field. The model did not indicate historic impact to vegetation outside the Boundary Creek catchment.
41 4.5 Stage 6: Technical studies – phase 2 of 2 ML/day has been released by Barwon Water into the upper reaches of Boundary Creek since 2002 to offset the reduction in Report title: 2017-18 Technical Works Program – Yeodene groundwater flow to the creek. Swamp study (Jacobs, 2018) A review of existing information undertaken for this study Scope highlighted: This study characterised the chemical and physical processes Although the licence holder of the on-stream storage on occurring in and around Yeodene (Big) Swamp to improve the Boundary Creek, known as ‘McDonalds Dam’, is required to pass understanding of the swamp’s behaviour and how that affects the all inflows to the dam between 1st November and 30th June - volume and quality of water being released downstream. including Barwon Water’s 2 ML/day supplementary flow –
metering since 2014 indicates that this has not been the case. Building on previous technical studies, the following is known: Previous release of flows was done by sight by the licence The monitoring program has shown that groundwater levels in holder resulting in inaccurate releases. the regional aquifer have declined. This has caused an adverse Metering of flows confirmed that not all the inflow, both passing impact in lower reaches of Boundary Creek, through the and supplementary, to the dam is being released - particularly mechanism of reduced flow in Boundary Creek. during critical summer low flow periods. The regional aquifer is present at the surface (outcrops) in the Since 1999, significant declines in pH of water have occurred in middle reach of Boundary Creek also known as Reach 2. Reach 3 of Boundary Creek and are related to the drying of acid Historically Reach 2 was a gaining reach (i.e. groundwater flows sulfate soils in Yeodene Swamp. Drying acid sulfate soils allows into the creek), however it is now a losing reach, where the creek acid water and heavy metals to discharge to the lower reach of loses flow to groundwater, through seepage. Boundary Creek. The use of the borefield over the past 30 years has been responsible for most (two thirds) of the reduction in groundwater A field program was undertaken to improve the understand flow to Boundary Creek. The dry climate experienced during the changes and potential causes of groundwater level fluctuations and same period accounts for the remaining part of the reduction surface water flow and water quality. (about one third). As the borefield was anticipated to impact stream flows in this part of the catchment, a supplementary flow
42 Outcomes Six possible management options were reviewed to remediate the swamp and of the six considered, inundating the swamp was Analysis of the data and field program concluded that: recommended as the most technically feasible option. The decline in pH (acidic water) appears to be correlated to reduced flow and in particular, periods when Boundary Creek Key features of inundation of the swamp included: has recorded cease to flow (no flow) at the Yeodene stream Increasing the supplementary flow initially from 2 ML/day to 3 gauge. ML/day downstream of ‘McDonalds Dam’ to account for the It can be asserted that the processes contributing to flow losses in reach 2 and to meet the recommended low flow reductions in Boundary Creek during 1990-1992 and since 1999 requirement of 0.5 ML/day at the Yeodene stream gauge. are the key factors driving pH change at those times. Those Installation of a hydraulic barrier to close off the fire trenches factors are known to be primarily groundwater extraction and and agricultural drains at the eastern end of the swamp to contribution from a drier climate. minimise water flow exiting the swamp, thereby helping to keep Cease to flow events have caused: areas saturated. - The swamp to dry and switch from a reducing to an oxidising environment, Although a management option was put forward in this report for - Potential Acid Sulfate Soils turning into Actual Acid remediation, Barwon Water established the Boundary Creek Sulfate Soils, and remediation working group in May, 2018. The remit of the group – - Release of acidic water with high concentrations of comprised of key agency stakeholders and the community – is to dissolved metals downstream of the swamp. design a remediation plan to address the key issues described The drying of the swamp and subsequent acidic water being above. released has been further exacerbated due to the 2 ML/day supplementary flow not reaching the swamp because the Following the establishment of this group, a Section 78 notice was entirety of flows have not been passed through ‘McDonalds issued by the Minister for Water in September, 2018. The Dam’ over the summer months. remediation of Boundary Creek and Big Swamp is fully contained within this notice. A representation of this can be found in Figure 14. For further information see section 7.3.
43
Figure 14: Boundary Creek historic impact
44 4.6 Stage 7: Licence application preparation
Report title: Predicted impacts from future operation of the Barwon Downs borefield (Jacobs, 2018)
Scope This study details the outcomes of groundwater modelling combined with a risk assessment methodology to identify environmental receptors at risk from future pumping under both constant and intermittent pumping scenarios over a 50-year time horizon (to 2067).
The objectives were to:
Inform Barwon Water’s upcoming licence application by using the groundwater model to predict potential impacts of future pumping to environmental indicators in the Gerangamete region, and Assess the level of risk associated with the predicted potential impacts of future pumping and from this, o Provide recommendations for appropriate triggers and off set measures where environmental receptors are at risk from the effects of future pumping, and o Provide commentary on the sustainability of the proposed pumping regimes for the duration of the next licence.
The approach was two phased and included:
Groundwater modelling using the recently updated and recalibrated model to predict changes in groundwater levels from future operation of the borefield under different operating and climate scenarios, and A risk assessment using the Ministerial Guidelines for Groundwater Licensing and Protection of Groundwater Dependent Ecosystems (DELWP, 2015) to determine the risk to environmental receptors associated with potential impacts. For receptors classified as high risk, the Guidelines note that further work is required to confirm the presence of high value GDEs, their connectivity to groundwater and sensitivity to changes in groundwater levels.
Different climate scenarios and pumping scenarios were used to understand the range of potential impacts to environmental receptors.
Four climate change scenarios were applied to four pumping scenarios to determine the influence of climate. The climate change scenarios are consistent with the Guidelines for Assessing Climate Change on Water Availability in Victoria (DELWP, 2016) and influence the volume of recharge to the aquifer and the timing for when the Barwon Downs borefield is predicted to be required.
45 Four pumping scenarios were developed in consultation with Barwon Water. Two scenarios assumed no pumping and were used to assess the impacts from pumping and the rate of recovery assuming there is no future pumping. Two scenarios assumed pumping at different rates and were used to compare the impacts of operating the borefield at a constant low rate or at higher rates on an intermittent basis. Volumetric entitlements for each scenario and groundwater modelling outcomes are set out in Table 4 and Table 4 respectively.
Table 4: Overview of modelling scenarios
Model scenario Yield Pumping regime Scenario description (ML) (ML) Scenario 0 0 0 Baseline scenario assumes no past or future pumping (no pumping) to understand the influence of climate only Scenario 1 0 0 Assumes no future pumping to understand the rate of (no future pumping) recovery of the aquifer system from historical pumping Scenario 2 Assumes a constant pumping rate of 4,000 ML every year regardless of 6,600 4,000 ML/year (constant future pumping) climate or demand until 2067
Scenario 3 Assumes an intermittent pumping rate until 2067 which 11,000 Max yearly rate: 12,000 ML (intermittent future pumping) is a similar operating regime to the past with proposed reduced Max 10-year limit: 60,000 ML volumetric entitlements
Table 5: Outcomes of the groundwater modelling
Theme Groundwater modelling outcomes The average recharge to the Lower Tertiary Aquifer (LTA) over the last 30 years is estimated to be 5,835 ML/year.
Recharge rates Recharge to the aquifer is predominantly where the aquifer outcrops at Barongarook High, in the Boundary Creek catchment. Recharge is predicted to decline by 8% under median climate change.
The estimated total volume of the Lower Tertiary Aquifer is 3,000,000 ML. Aquifer volume
46 Theme Groundwater modelling outcomes The maximum annual volume extracted during the constant rate pumping scenario is 4,000 ML or 0.1% of the total aquifer volume. The maximum annual volume extracted during the intermittent pumping scenario is 12,000 ML or 0.4% of the total aquifer volume. Changes in regional groundwater levels were used to assess the potential for changes in Regional groundwater levels watertable aquifer which could cause adverse impacts at the surface. Groundwater levels close to the borefield have recovered approximately 80% since 2010. Groundwater levels are predicted to reach 90% recovery within 10 years if there is no future pumping. Groundwater level recovery
The rate of recovery is slower further away from the borefield. At Boundary Creek, groundwater levels will take between 20 to 30 years to recover if there is no future pumping. Model over-predicts drawdown in hydrogeological layers near the surface and south east of the Bambra Fault
Maximum drawdown predicted is higher near the Barwon Downs borefield for the intermittent pumping scenario compared to the constant rate pumping scenario, as the short-term extraction Drawdown in the regional aquifer (Lower rates are much higher. Drawdown near Boundary Creek, Kawarren and Gellibrand River is Tertiary Aquifer) predicted to be similar to the constant rate pumping scenario.
Predicted drawdown as a result of potential future pumping is typically less than the predicted drawdown from historic pumping. The total drawdown that will be observed will depend on when pumping re-commences and on the degree of recovery up to that point. The model over predicts drawdown in the watertable aquifer for two reasons: Drawdown in the watertable aquifer The model predicts drawdown in the centre of the hydrogeological unit and observed data indicates this drawdown has not propagated to the surface and Watertable in the local alluvial aquifers are not included in the model.
47 Risk assessment outcomes across the study area The key outcomes of the risk assessment for vegetation, potential acid sulfate soils and rivers is detailed in Table 6.
Table 6: Outcomes of the risk assessment for environmental receptors across the study area
Environmental Risk assessment outcomes Maximum residual receptors risk ranking Vegetation monitoring of the 14 sites has demonstrated that most of these sites have local alluvial aquifers that are buffered from impacts from drawdown induced by groundwater pumping.
The exception to this is T2, which is located in Reach 2 of Boundary Creek where groundwater levels have declined in response to pumping.
There is no evidence from observed data that predicted drawdown in the regional aquifer as a result of historic pumping has propagated to the shallow alluvial aquifer at any other monitoring sites. Vegetation across High risk in small areas the catchment Over the majority of the study area vegetation is considered to be at low risk from pumping due to where the regional the presence of physical mitigating factors such as the regional aquitard, Bambra Fault and alluvial aquifer outcrops and aquifers. there are no local alluvial aquifers. Areas of high risk exist where the regional aquifer outcrops and there are no alluvial aquifers. For example, on the Barongarook High, along Reach 2 of Boundary Creek and small areas along the Gellibrand River.
In summary groundwater dependent vegetation across 98% of the study area is classified as low residual risk and 2% is classified as high residual risk. Vegetation dependent on groundwater in the regional aquifer in the areas of high risk has the potential to be impacted by drawdown from the borefield.
Potential acid sulfate soils Naturally occurring PASS sites have the potential to be oxidised and become acidic, as a result of declining groundwater levels in response to pumping. High risk in Reach 2 of Site specific investigations at the four PASS monitoring sites indicate that all sites have a local shallow Boundary Creek and alluvial aquifer overlying the regional aquifer/aquitard. Barwon River East Branch. Monitoring has demonstrated that PASS sites dependent on local alluvial aquifers are buffered from impacts from drawdown induced by groundwater pumping.
48 Environmental Risk assessment outcomes Maximum residual receptors risk ranking Over the majority of the study area PASS are considered to be at low risk from pumping due to the presence of physical mitigating factors such as the regional aquitard, Bambra Fault and alluvial aquifers.
There are small areas of high risk in along Reach 2 of Boundary Creek and Barwon River East Branch. Naturally occurring PASS sites are present in these areas and the regional aquifer outcrops at these locations.
Although there are small areas of high risk (as determined by predicted drawdown) along the Gellibrand River, there are no known areas with naturally occurring PASS in this location.
Barwon River (east Barwon River East branch is thought to be gaining flow from groundwater in some sections where it branch) flows over the Lower Tertiary Aquifer to the south east of the borefield. The model over predicts drawdown on the south east side of the fault due to the representation of the fault, the aquitard and local alluvial aquifers. This means that model predictions are conservative and most likely an overestimate.
Predictive scenario modelling indicates that the greatest risk of impact to the Barwon East Branch will Medium occur to the south of the intersection between the river and the Birregurra-Forrest Road.
Given the potential physical mitigating factors, the Barwon River is classified as potential medium risk where the East Branch flows over the aquifer and aquitard south east of the Bambra Fault. The model has highlighted there could be a potentially significant impact to surface flows in the East Branch during low flow periods.
Barwon River (west The mitigated risk to the West Barwon River is considered low where it flows over the aquifer and branch) aquitard due to the presence of alluvial aquifers. Low
Barwon River Downstream of the confluence the mitigated risk is considered low as alluvial aquifers are present. Low (confluence) Dividing Creek Dividing Creek is a losing creek that is disconnected from the regional aquifer.
Medium The risk classification for Dividing Creek is medium because although there is a low likelihood that the stream is connected to the regional aquifer, more than 2 m of drawdown is predicted. 49 Environmental Risk assessment outcomes Maximum residual receptors risk ranking Gellibrand River The Gellibrand River is a key discharge feature for the regional aquifer. Alluvial sediments are present in the floodplain and this local aquifer will be buffered from drawdowns predicted in the regional aquifer. Medium The risk to the Gellibrand River is considered to be medium risk given the presence of an alluvial aquifer. However, are some small areas of high risk where the alluvial aquifer may not be present and the Lower Tertiary Aquifer outcrops at the surface. Porcupine Creek Porcupine Creek flows over the aquitard and into Loves Creek which is a tributary of the Gellibrand River. The risk to the creek is considered to be low given the potential physical mitigating factors such Low as the presence of alluvial aquifers that buffer the effect of pumping.
Ten Mile Creek Ten Mile Creek is a tributary of Loves Creek and flows over a small outcrop of the Lower Tertiary Aquifer. The creek is considered to be a gaining creek where it flows over the aquifer.
Medium Modelling predicts that there is a low to medium risk to the creek, given the physical mitigating factors such as the presence of alluvial aquifers.
Yahoo Creek Yahoo Creek is also a tributary of Loves Creek and similar to Ten Mile Creek, the creek flows the regional aquifer in the upper reaches.
Medium Given the physical mitigating factors such as the presence of alluvial aquifers, the modelling predicts that there is a low risk to majority of the creek and small areas of medium risk.
Loves Creek Loves creek predominantly flows over the aquitard, however the aquifer outcrops near the confluence with the Gellibrand River, where drawdown is predicted to be minor (less than 0.1 m).
Low Given the presence of mitigating factors such as the presence of alluvial aquifers, the risk is considered to be low as a result of low connectivity with the regional aquifer.
Barongarook Creek Barongarook Creek is located north of Boundary Creek and flows north west to Lake Colac. The creek flows over the aquitard and modelling predicts that there is a medium risk in the upper reaches of Medium Barongarook Creek and a low risk for the lower reaches.
50 Risk assessment outcomes in Boundary Creek
Historical pumping from the Barwon Downs borefield to date has highlighted that the middle reach in the Boundary Creek catchment has been impacted as a result of groundwater extraction and ineffective offset measures. Lack of flows in Boundary Creek has also led to the oxidation of acid sulfate soils, resulting in acidic water exiting the swamp.
The middle reach of the creek flows over outcropping regional aquifer where there are no significant alluvial aquifers present to buffer the impacts. Table 7 summarises the risk assessment outcomes for Boundary Creek.
Table 7: Outcomes of the risk assessment for environmental receptors in Boundary Creek catchment
Environmental Risk assessment outcomes in Boundary Creek Residual risk receptors ranking Vegetation at Boundary Vegetation is at a high risk of potential impact in the Boundary Creek catchment upstream of Yeodene Creek Swamp where the aquifer outcrops and there is limited or no alluvial aquifer. Although there are other areas of high risk identified across the catchment, the aquitard is present over much of this area and High the model is known to over-predict the drawdown in the watertable aquifer, particularly where the aquitard is present.
Potential acid sulfate soils Similar to the results stated for vegetation (above), areas with PASS are at a high risk of potential at Boundary Creek impact in the Boundary Creek catchment where the aquifer outcrops. High
Boundary Creek flows Reach 1 is a low risk classification as this reach is not directly connected to the regional aquifer. Low reach 1 Boundary Creek flows Reach 2 of Boundary Creek, where the creek flows over the regional aquifer between McDonalds Dam reach 2 and Yeodene Swamp, is considered to be at high risk of potential impact.
The predicted reduction in groundwater contribution to the river is around 2 ML/day which is more than 100% of low flows. The risk associated with potential future pumping is predicted to be marginally High less than historical pumping.
Regardless of future pumping, reach 2 of Boundary Creek is predicted to take 20-30 years to recover from historic pumping in terms of baseflow contribution if remediation works is not undertaken. Boundary Creek flows Reach 3 is a medium risk classification as this reach is not directly connected to the regional aquifer. Medium reach 3
51 Conclusions Exceptions to this are Reach 2 of Boundary Creek and potentially the middle reaches of the Barwon River East Branch, which are Groundwater modelling and risk assessment indicate that both classified as high risk. operating the borefield according to the intermittent pumping scenario can considered to be sustainable, providing the current The majority of the vegetation is considered to be at low risk trigger levels are maintained and additional site-specific studies from pumping due to the presence of physical mitigating factors are completed in areas identified as high risk, to confirm that such as the regional aquitard, the Bambra Fault and alluvial high value GDEs are either not present or not impacted by aquifers. Approximately 2% of the area is at high risk in areas pumping. located along Reach 2 of Boundary Creek, Barwon River East Branch and the Gellibrand River. There is no comparable difference in overall environmental risk between operating the borefield at a constant rate of 4 GL/year The drawdown predicted at the PASS monitoring sites is within compared to intermittent pumping. the range of drawdown experienced in the past and a baseline assessment in 2015 highlighted there was no evidence of The predicted impacts associated with operating the borefield drawdown from the borefield influencing PASS at these sites. are either similar to, or less than, the impacts that have occurred historically. That is, predicted drawdown is typically less than what was observed during the Millennium Drought and is not Report title: Low flow recommendations for Boundary Creek predicted to be any worse. (Jacobs, 2018) The model over-predicts drawdown at the surface as a result of physical mitigation constraints that restrict groundwater flow Scope (and therefore drawdown impacts) present in real world, but not The objective of this study was to quantify the minimum low flow represented well in the model. These include the presence of volume required to support current ecological values in Boundary alluvial aquifers, the Bambra Fault and the regional aquitard. Creek. Due to their varying ecological and hydraulic characteristics, Most of the catchment will not be significantly impacted by the minimum low flows required to support the ecological values of pumping because of physical hydrogeological barriers that each reach have been identified independently from each of the buffer drawdown in the regional aquifer at surface level. other reaches, without consideration of the operational constraints of the system and are outlined in the table below. If a higher flow is While operating the Barwon Downs borefield is likely to reduce required through an upstream reach in order to deliver the groundwater contribution to rivers and creeks, the risk recommended flow in a downstream reach, this would not be associated with these impacts is typically low to medium. detrimental to the values or objectives of the upstream reach. The
52 low flow recommendations represent the minimum flow required to (DEPI, 2013). The most significant adaptation is that the current achieve the management objectives. study focusses on low flows, as this is the flow component most likely to be affected by changes to groundwater-surface interactions The flow recommendations for the “damplands” and Yeodene (Big) due to the operation of the Barwon Downs borefield. Swamp, were considered in detail as part of a separate study, the Yeodene Swamp Study (Jacobs, 2018), with results incorporated into Outcomes this study. Table 8 provides a consolidated summary of the ecological condition assessment of each reach and sub-reach (i.e. good, This study considers only the volume of low flow required to moderate or poor ecological condition), the management objective support the ecological values of Boundary Creek and assumes that (i.e. maintain or improve) and associated targeted outcomes and the water is of suitable quality (particularly pH) to support the the low flows required to meet the management objectives. species and communities of Boundary Creek. The provision of suitable quality water in Reach 3 will require remediation of the Yeodene Swamp, which is discussed in detail in the Yeodene Swamp Study (Jacobs, 2018).
Management objectives for the Boundary Creek catchment were defined as: Maintain current ecological condition in Reach 1 (upstream of McDonalds Dam), Reach 2a (channelized section downstream of dam) and Reach 2b (damplands), and Improve the current ecological condition in Reach 2c (Yeodene Swamp) and Reach 3.
The low flow volume required to support the aquatic values of Boundary Creek has been determined using an approach adapted from the FLOWS method, which is the standard method used to define environmental flow requirements for Victorian waterways
53 Table 8: Ecological condition (i.e. good, moderate, poor), management objectives (i.e. to maintain or improve), targeted physical and ecological outcomes and associated minimum low flow requirements for Boundary Creek.
Ecological Management Targeted physical and Reach Flow volume Description condition objective ecological outcome Cease to flow periods are not required to maintain the ecological condition of the reach, however, they could occur occasionally (e.g. once a year) with Cease to flow minimal impact on the ecological condition of the Provide pool habitats for stream provided the cease to flow periods are of fish, frogs, vegetation. short duration (e.g. less than two weeks). 1 Good Maintain Allow fish to move A flow of 0.5 ML/day corresponds with a water between pools. Minimum low flow of depth of between 30 and 70 cm in pools and 3 cm Mix pools. 0.5 ML/day (measured of water over riffles. This would provide habitat for at the gauge upstream small bodied fish (e.g. Southern Pygmy Perch, of “McDonalds Dam”) Mountain Galaxias), macroinvertebrates and frogs and allow movement of fish between pools. Cease to flow periods are not required to maintain the ecological condition of the reach, however, they could occur occasionally (e.g. once a year) with Cease to flow minimal impact on the ecological condition of the Provide pool habitats for stream provided the cease to flow periods are of fish, frogs, vegetation. short duration (e.g. less than two weeks). 2a Moderate Maintain Allow fish to move A flow of 0.5 ML/day corresponds with a water between pools. Minimum low flow of depth of between 70 and 80 cm in pools and 12 cm Mix pools. 0.5 ML/day (measured of water over riffles. This would provide habitat for at the gauge small bodied fish (e.g. Southern Pygmy Perch, downstream of Mountain Galaxias) macroinvertebrates and frogs “McDonalds Dam”) and allow movement of fish between pools. Cease to flow conditions are not required to Maintain waterlogged maintain the condition of the reach, however, he soils to continue to 2b Good Maintain Cease to flow soil in the “damplands” would stay waterlogged for support Swampy short periods (less than 2 weeks) without inflow Riparian Vegetation, with minimal impact on the ecology of the area.
54 Ecological Management Targeted physical and Reach Flow volume Description condition objective ecological outcome macro-invertebrates and The water balance analysis and volume of water Minimum low flow of Otway Bush Yabby. released historically from “McDonalds Dam” 1.5 ML/day (measured indicates that 1.5 ML/day measured at the gauge at the gauge immediately downstream of “McDonalds Dam” is downstream of sufficient to maintain waterlogged soils in the “McDonalds Dam”) “dampland”. Must be prevented. The main objective for this reach is to maintain inundation of the swamp to Cease to flow prevent oxidation of soils and improve water quality in Reach 3. Maintain waterlogged soils in the swamp, reducing the oxidation potential of the acid sulfate soils, with Flow (of any magnitude) the objective of decreasing the incidence of very recorded at the Yeodene low pH water in Reach 3. Adaptive management flow gauge throughout may lead to the refining of the low flow the year Minimum low flow of recommendation to ensure flow at the Yeodene Improve the water 2c Poor Improve 1.5 ML/day (to provide gauge is maintained throughout the year. quality as indicated by 1.5 ML/day in Reach pH. Water quality in 2c, 3 ML/day needs to Boundary Creek is The water balance analysis and volume of water be measured at the discussed in detail in released historically from “McDonalds Dam” gauge downstream of Jacobs (2018). indicates 3 ML/day is required (measured at the “McDonalds Dam”) flow gauge immediately downstream of “McDonalds Dam”) from a volumetric perspective (e.g. independent of the pH of the water) to achieve a flow of 1.5 ML/d at the “damplands” and hence achieve the ecological objectives of the “damplands” and the Yeodene Swamp. Cease to flow periods are not required to maintain Provide pool habitats for the ecological condition of the reach, however, they fish, frogs, vegetation could occur occasionally (e.g. once a year) with 3 Poor Improve Cease to flow and possibly occasional minimal impact on the ecological condition of the use by Platypus. stream provided the cease to flow periods are of short duration (e.g. less than two weeks).
55 Ecological Management Targeted physical and Reach Flow volume Description condition objective ecological outcome Provide opportunity for A low flow of 0.5 ML/day in Reach 3 corresponds to fish movement between pools up to 40 cm deep and shallow runs of pools approximately 6 cm depth. This would provide Minimise frequency and habitat for small bodied fish (e.g. Southern Pygmy duration of cease to Minimum low flow of Perch), macroinvertebrates and frogs and allow flow events. 0.5 ML/day (measured movement of fish between pools. Flow of that Improve the water at the Yeodene flow depth may also allow occasional use by Platypus quality as indicated by gauge) that enter the creek from the Barwon River to pH. Water quality in forage, however, the structural habitat (clear banks) Boundary Creek is are unsuitable for resident individuals. discussed in detail in Jacobs (2018).
Report title: Groundwater Assessment Report (Jacobs, 2018)
Scope The objective of the Groundwater Assessment Report is to present the available technical data and describe the approaches used to determine the potential impacts associated with the future operation of the Barwon Downs borefield.
This report collates elements from the other technical documents and provides updated technical data collected since previous reports were finalised.
This report also outlines recommended monitoring requirements and proposes trigger levels and actions to avoid or off-set potential impacts to environmental receptors.
Outcomes
No new outcomes due to this being a collation of previous work
56 Impact to Boundary Creek flows from groundwater pumping 5 Community Reference Group and passing flows from McDonalds dam, Barwon Water established a Community Reference Group (CRG) in Impact to the water quality being released from Big Swamp 2013 to help scope the monitoring program and supporting from groundwater pumping, technical studies to target areas of community concern. Acid sulfate soils, the presence and extent of both actual and potential acid sulfate soils in the catchment, The CRG’s objectives were to: Fire management for Big Swamp due to the presence of peat, advise on key community concerns about the Barwon Downs Climate change and drought impacts, including how it affects borefield to assist in further refinement of the monitoring and recharge rates, groundwater extraction and streamflow runoff, investigation program, Impact to groundwater dependent ecosystems both aquatic and provide advice on engagement with the broader community in terrestrial including springs, relation to the borefield, and Subsidence and salinity, monitor implementation of the revised monitoring program. Recharge rates, including the opportunity to investigate artificial recharge through an aquifer storage and recovery scheme The issues the CRG raised were an important contribution because it and/or winter storage, raised confidence that the right monitoring data would be captured Social and recreational impacts including farming activities and to specifically target known areas of community concern. These customer demand, use of alternative water sources, and were included in the new monitoring program. Community engagement including education and information sharing with the community, the importance of information 5.1 Checking in with the CRG being accurate and consistent, and the need to be more open Key issues that the CRG raised for the new monitoring program and transparent during the upcoming licence renewal process. were: The original appointed term of the CRG was one year, to allow Interaction with other aquifers and the movement of enough time to refine the scope of the monitoring program to groundwater, specifically the Gellibrand groundwater integrate with community concerns. management area and the Gellibrand River and tributaries,
57 After achieving this outcome in 2014, the CRG made the decision to report to Barwon Water. The CRG presented a recommendations remain active and to have an ongoing role in providing feedback to report to the Barwon Water Board at the May 2018 Board Meeting. Barwon Water as findings from the monitoring program and At the time of this recommendation report prepared by the CRG, particularly, the technical studies emerged. Barwon Water the Section 78 Notice had not been issued to Barwon Water. At that supported this decision. time, Barwon Water had made commitments to a three phased
approach, including remediation, testing and operation. The CRG’s A total of 23 meetings were held. These meetings enabled the CRG response in the recommendations below references this phased to test ideas and interrogate the monitoring results with our approach. This three phased approach has now been superseded by experts, and allowed us to see what was important to the a two phased approach in line with the Section 78 Notice. Refer community. section 7.3.
In addition to these meetings, the CRG supported the licence The CRG summary recommendations from their report are shown renewal process by attending community information sessions in below: May 2014 and again in August 2017. Members of the CRG also attended the broader community and stakeholder workshops held 1. “The CRG supports the renewal of Barwon Water’s licence. in late 2017 to provide their perspective and deeper knowledge 2. The CRG supports the approach taken by Barwon Water to a 3- about the monitoring activities and technical studies. phase implementation of any future production pumping at the borefield. Through their role, the CRG have twice presented to the Barwon 3. The CRG believes that all test pumping and production pumping Water Board to inform the Board Directors of the community issues (BW’s phases 2 and 3) should be suspended for the period of the identified by the group, key considerations for the licence proposed licence renewal. application and their recommendations for consideration in this 4. The CRG recommends that the licence volume for the licence licence application. renewal period be restricted to a maximum of 100 ML per year for maintenance purposes only. 5.2 Outcomes of the CRG At the conclusion of the CRG’s process, the CRG met independently several times to discuss and agree on recommendations to put in a
58 5. The CRG wishes to ensure that if phase 2 and/or 3 pumping is permitted in the proposed licence period, strong licence conditions as set out in this (CRG) Community Reference Group thoughts and reflections report be attached to any such pumping. 6. The CRG hopes that any such strong conditions would “The members of the CRG thank Barwon Water for the opportunity to take part in endure beyond any licence renewal, so that, if the such a deep process of engagement – we have not always agreed, but our implementation of phases 2 and/or 3 were to take disagreements have led to better outcomes both for the community and for BW more than 15 years, certainty can be ensured without (Barwon Water).” the need for such extensive and costly interventions at subsequent licence renewal intervals.” “BW’s (Barwon Water’s) staff and consultants have been prepared to explore the areas of concern we raised. We appreciate their openness, their professionalism 5.3 Barwon Water response to CRG and their friendship over the journey. We also note with pleasure that new spirit of Barwon Water has carefully considered the Community openness and genuine listening with have come through with recent changes at Reference Group’s recommendations report. BW (Barwon Water).”
Barwon Water is no longer proposing a three phased “We wish to draw the Board’s attention to issues which are beyond the licence approach for the Barwon Downs borefield which has application but which we believe to be of general benefit. First, in-depth meant that not all comments in the Community investigation of the potential use of the aquifer for storage and recovery of high Reference Group’s recommendations report are in surface water flows to augment the natural storage capacity of the aquifer; second, context. Subsequently, not all recommendations can be to ensure that Southern Rural Water revise the current permissive consumptive delivered. That said, we believe that there will be more volume for the aquifer to ensure that Barwon Water remains the only licence alignment than divergence in outcomes for the next holder.” licencing period.
The CRG’s full letter and Barwon Water’s proposed “We also request that this report be forwarded to SRW at the same time as the response to this document is included as a supporting proposed licence application so that the views of the CRG be taken into account, document – refer to Table 12 for the register. and also to demonstrate the extensive nature of community engagement which Barwon Water has undertaken.”
59 Future groundwater extraction and whether current practices 6 Broader consultation were sustainable, In addition to consultation with the CRG, the following broader Concern around the impact of acid sulfate soils particularly on consultation was undertaken: water quality, and that Environmental flows into receiving water bodies needed to be Community information sessions, protected from groundwater pumping. Briefings with regulatory agencies including DELWP, Corangamite Catchment Management Authority, Surf Coast 6.2 Community and stakeholder workshops Shire, Colac Otway Shire and Southern Rural Water, Barwon Water hosted three community and stakeholder workshops Briefings with landcare groups including Upper Barwon, on the groundwater licence renewal between late September and Winchelsea, LAWROC, early December 2017. Progress updates to Barwon Water’s Customer and Attended by approximately 30 community members and key Environmental Consultative Committees, and stakeholders, the workshop provided participants with an Community and stakeholder workshops (see below). opportunity to talk with Barwon Water's Chairman (Jo Plummer) and The following details the key outcomes from that consultation Managing Director (Tracey Slatter) around a number of key which has helped shape our licence application. community concerns and outcomes relating to the borefield. Participants were then asked to consider and provide feedback on 6.1 Community information sessions how the borefield should be operated to ensure affordable water Barwon Water held one community information session in May security for the region while balancing the needs of the 2014 and another two sessions in August 2017, to update the environment. community and stakeholders about the licence renewal application process and share the outcomes of the monitoring activities and During workshop two, participants generated a recommendations technical studies. Approximately 35 people attended the sessions in report, which it provided to Barwon Water for consideration and 2017. response at workshop three. There were nine community outcomes
identified, these were: During these sessions, a number of community concerns and interest areas were identified and included:
60 1. Trust and community consultation 2. Flora, fauna and environmental protection 3. Sulphate protection, rehabilitation of Boundary Creek, Big Swamp, Barwon River 4. Adaptive licence 5. Sustainable yield 6. Platypus study 7. Monitoring assessment 8. CCMA Partnership 9. Aquifer recharged to pre-pumping levels
At workshop three, Barwon Water presented its proposed interpretation and actions in response to the community outcomes identified at workshop two. Participants were asked to share their perspectives and provide feedback about what they liked about each action and what would improve each action. The community outcomes and on ground success measures provided guidance to Barwon Water as what actions were required to achieve this. The actions were presented back to the community in workshop 3.
Figure 15: Community Workshop in Colac (September 2017) At the conclusion of workshop three, Barwon Water committed to reviewing and considering all community and stakeholder feedback in the development of the licence application.
Community workshop 1, 2 and 3 reports can be found in other supporting documents – see Table 12 for register.
61 7 Our commitments to the community As outlined in section 6, the community workshop participants told us they wanted Barwon Water to deliver on nine key outcomes, including how they would like to see success measured on ground. This section describes Barwon Water’s commitments in response to what we heard from the community. In response, Barwon Water proposed five actions as summarised in Figure 16 and below in Table 9.
Figure 16: Our response to community inputs
62
Table 9: Barwon Water’s proposed actions in response to the community’s nine key outcomes.
Proposed action Commitment We will not operate the borefield, except for maintenance and emergency purposes until the requirements of We will manage the ongoing the s.78 notice are met. This approach aligns with the community’s desire for Barwon Water to be conservative operation of the Barwon Downs in its approach to operating the borefield. borefield conservatively We are proposing a significant reduction in volumetric entitlements (compared to the previous licence). We will use triggers to take preemptive action to manage potential impacts ahead of them occurring to avoid We will establish an adaptive unacceptable impacts. These triggers will be reviewed and adapted if needed. monitoring program We will implement a monitoring program that is flexible and responsive to what is being observed and
measured on the ground.
We will develop and implement a We will work with the community and our stakeholders to design and implement a remediation plan for remediation plan for Boundary Boundary Creek in accordance with the requirements of the Section 78 notice. Creek We will provide stock water via provision of a dedicated pipeline to affected landholders in the lower reach of (this will be undertaken in accordance with the Boundary Creek. notice issued under s78 of the Water Act, 1989) We will engage an independent expert to undertake a platypus study for the Upper Barwon. We will submit all technical studies used in the preparation of this application to Southern Rural Water to be We want to build knowledge and independently peer reviewed. trust in the science with the We will establish a citizen science program to build a common database of shared information. community We will publish all technical studies and monitoring data on our website so that it is accessible to all. We will establish a Barwon Downs Borefield Working Group for the duration of the next licencing period who We will engage more interactively will meet at least twice a year to tap into local knowledge and expertise. with the community We will host an information session in Colac annually to update the broader community of our performance
against the licence.
Table 10 below illustrates how each proposed action will contribute towards each community outcome.
63 Table 10: How Barwon Water’s actions will meet the nine community outcomes We will develop and A conservative approach Proposed Barwon Water actions (horizontal) implement a remediation Building knowledge and to the operational Establishing an adaptive Interactive engagement plan for Boundary Creek trust in the science with management of the monitoring program with the community Community outcomes (vertical) (this will be undertaken in the community borefield accordance with the notice issued under s78 of the Water Act, 1989)
Trust and community consultation
Flora, Fauna and Environmental Protection
Sulphate Protection, Rehabilitation of Boundary Creek, Big Swamp, Barwon River
Aquifer Recharged
CCMA Partnership
Adaptive Licence
Monitoring/ Assessment
Platypus Study
Sustainable yield
64 7.1 Managing the ongoing operation of the borefield conservatively
7.1.1 Barwon Downs Operational Plan Despite the long term scientific data and predictive groundwater model confirming that future operation of the borefield is sustainable, there remains community concern and lingering distrust due to the historic impact of the borefield and subsequent ineffective management measures to offset predicted impact.
The Section 78 Notice imposes two phases for operation during the 15 year licencing period, which includes:
Phase 1: Maintenance and emergency use only, (as directed by the Section 78 Notice) Phase 2: Sustainable long term operation (after the Section 78 Notice is rescinded)
The phased approach is consistent with the need to be conservative as identified during our community consultation process. Production pumping of the borefield can only occur when the requirements of the Section 78 Notice are met and the notice is rescinded.
7.1.2 Proposed Volumetric Entitlements We are applying for volumetric entitlements at a level which achieve sustainable groundwater use.
Importantly, Barwon Water is now seeking a reduction of approximately 40% in maximum daily, annual, ten year and fifteen-year extraction rates. The proposed reductions in volumetric entitlements compared to the existing borefield licence are described in Table 11 below.
65 Table 11: Proposed volumetric entitlements Condition Current Proposed Comment
Maximum daily rate 72 45 As a result of the work undertaken by Barwon Water, it is apparent that the existing Barwon Downs Borefield infrastructure is not capable of extracting in excess of 45ML/d without significant augmentation. Barwon Water does not need more than 45ML/d and the proposed daily maximum has been amended to reflect this. Maximum annual rate 20,000 12,000 At no stage in the last 15 year licence period has Barwon Water extracted 20,000ML/year. The maximum annual rate has been reduced to reflect a volume which has typically been extracted in the past during a drought, while also providing for water security in accordance with Barwon Waters Urban Water Strategy. Maximum 10-year rate 80,000 N/A Barwon Water has removed the 10-year maximum rate and replaced it with a 15-year maximum rate to ensure it is contained and aligned within the groundwater licence period. The maximum amount of 60,000 ML over 15 Maximum 15-year rate N/A 60,000 years is 33% lower than the estimated historical recharge rate of the Lower Tertiary Aquifer (LTA) over the past 30 years.
The 15-year maximum rate of 60,000ML is consistent with a long term 100- year average of 4000ML/year. Long term (100 year) 400,000 N/A It is not appropriate to include a 100-year extraction limit in a 15 year licence. extraction It has therefore been removed. The 400,000 ML over 100 years results in an average of 4000 ML/y over 100 years. The proposed maximum extraction of 60,000 ML over 15 years results in the same average of 4000 ML/y over 15 years.
This is further detailed in Appendix A – Criteria for the assessment under Water Act
66 7.2 Establishing an adaptive monitoring program The community told us that they would like an adaptive monitoring and assessment program for this licence which is flexible enough to respond to what is happening on the ground.
The intent of combining the monitoring and assessment program with the development of appropriate triggers is to pre- empt the possibility of unacceptable impacts to environmental indicators in the catchment. An adaptive approach means that the monitoring program and triggers will be responsive to and can be adjusted as any new information is obtained.
The monitoring and assessment program as well as the triggers will be reviewed periodically by the Barwon Downs working group to ensure that there is continued early detection of potential impacts to environmental indicators associated with groundwater extraction.
The monitoring and assessment program is detailed in Barwon Water’s Groundwater Assessment report. It includes items to continue monitoring, areas where risks have been identified and proposed additional monitoring and triggers to protect environmental indicators as summarised below.
7.2.1 Continued monitoring Barwon Water will continue with monitoring activities as recommended by the technical work completed to date. We have reliable baseline data from our monitored sites that we can continue using during the course of the licence.
7.2.2 Proposed additional monitoring and triggers to protect environmental indicators The objective of a trigger level is to initiate an action or management response to pre-empt or keep a watching brief of how environmental indicators are responding to groundwater extraction.
The proposed triggers are also outlined in Barwon Water’s Groundwater Assessment Report, included as part of our submission.
7.2.3 Investigate Aquifer Storage and Recovery In response to community feedback and a recommendation by the Community Reference Group, Barwon Water commits to further investigate whether the Lower Tertiary Aquifer could be suitable to be used for Aquifer Storage and Recovery (ASR) in the long term future
67 and, if so, whether this presents any opportunities for future consideration. Implementation of ASR is not proposed as part of Barwon Water’s groundwater licence renewal application.
7.3 Developing and implementing a remediation plan for Boundary Creek Barwon Water shares the same desire of the community that Boundary Creek and Big Swamp must be remediated. As evidenced on the ground - and confirmed by our groundwater model - pumping has had unacceptable environmental impacts in this catchment. Barwon Water is committed to implementing remediation actions.
7.3.1 Develop and Implement Remediation Plan as outlined in the Section 78 Notice Southern Rural Water has since issued a notice (under Section 78 of the Water Act) for Barwon Water to develop and implement a remediation plan for Boundary Creek, Big Swamp and surrounding environment impacted by past groundwater extraction. The notice also restricts Barwon Water’s use of the Barwon Downs borefield to no more than required for maintenance and emergency response until the notice is rescinded.
7.3.2 Boundary Creek stock pipeline operational The landholders in the lower reach of Boundary Creek downstream of the swamp have had ongoing issues with access both as to the quantity (extended periods of no flow) and quality (acidic water due to low pH levels) of water which has impacted their ability to rely on the creek for stock water. After ongoing engagement with the affected landholders, Barwon Water has committed to construction of a dedicated stock pipeline so that these landholders have access to a reliable quantity and quality of stock water.
7.3.3 Platypus study During consultation with the community, the aspiration to return platypus to the catchment came through very strongly and was identified as one stand-alone community outcome. Barwon Water is proposing that a platypus study of the Upper Barwon be undertaken by an independent expert.
68 7.4 Building knowledge and trust in the science with the community The community has told us that there are some continued concerns relating to ongoing borefield operation due to historic impacts in the Boundary Creek catchment and a low confidence that our proposed volumetric entitlements are sustainable due to a distrust of the science supporting this application.
To continue building trust and knowledge in the community we will be open and transparent in how we share information with the community and our stakeholders and importantly, involve the community in collecting data to capture their local knowledge and expertise.
7.4.1 Submission of all technical work
Barwon Water will submit all technical reports and supporting documentation for this application to Southern Rural Water to undertake an independent review. We will provide support and additional information as required by the water resource assessment process.
7.4.2 Implement citizen science program and establish database of shared information
To better capture local knowledge and expertise, we will work with the community and our stakeholders to establish a citizen science program to build a common database of shared information.
7.4.3 Publish all technical studies We will publish all technical studies and monitoring data on our website so that it is accessible to all.
69 7.5 Interactive engagement with the community The community have told us that the restoration of trust is really important to achieving better outcomes for the catchment and the groundwater licence.
We acknowledge that the restoration of community trust will take some time but nonetheless, we are genuine in our intent to partner with the community and our stakeholders for the next licencing period to embed the community’s nine outcomes and address concerns sufficiently so that when the borefield is used in future, there is greater community acceptance.
In order to continue engaging more deeply, we want the community to be more involved throughout the next licencing period to keep holding Barwon Water to account.
7.5.1 Establish the Barwon Downs working group
We propose to establish a Barwon Downs working group. The working group will meet at least twice a year with their role to:
Share local expertise and knowledge with Barwon Water, and Be involved in the review of performance against the licence conditions.
7.5.2 Annual Information Sessions
We will host an information session in Colac annually to update the broader community of our performance against the licence.
7.5.3 Advise community of any changes
We will inform the community before any significant event such as production pumping occurs. We will engage with the community so that we are transparent about any changes in licence conditions, triggers or in the monitoring and assessment program during the licencing period.
70 The application meets all the legal requirements of the Water Act, 8 Conclusion 1989. Barwon Water has given due consideration to all aspects influencing the need for this groundwater licence renewal.
In deciding whether to apply for a renewal, we weighed up historic adverse impacts caused by groundwater pumping, technical studies that improved our understanding of future impact, community concerns about the sustainability of extraction and the region’s ongoing need to access this critical resource.
We know that there is scientific rigour behind our application and have confidence that future pumping can be managed sustainably. Protecting the natural assets upon which we all depend is equally as important to us as safeguarding the region’s water security.
We have listened to the community and have heard the outcomes important to them. Our promise to continue rebuilding trust and using the Barwon Downs borefield sustainably will be delivered through our commitments to the community.
With this confidence, and the obligation to provide essential, secure and affordable water services to our community, we are applying for a renewal of our Barwon Downs borefield groundwater licence.
71 9 Supporting documents
9.1 Appendix A – Criteria for the assessment under Water Act 1989
9.2 Groundwater Assessment report
9.3 Other supporting documents
Table 12: Register of supporting documents Supporting documents Author, Year
Report addressing existing licence conditions Barwon Water, 2018
Ministerial Notice – section 78 Southern Rural Water, 2018
Urban Water Strategy Barwon Water, 2017
Economic Cost Analysis for the 2019 Barwon Downs licence renewal Barwon Water, 2018 *Note: this report utilises the current licence volumes. The report will be updated to reflect the reduction in proposed volumes in early 2019. Community Reference Group cover letter and recommendations report Community Reference Group; 2018
Barwon Water’s response to the Community Reference Group’s recommendations report Barwon Water; 2018
Workshop 1 – Community and stakeholder feedback report MosaicLab; 2017
Workshop 2 – Community and stakeholder recommendations report MosaicLab; 2017
Workshop 3 – Community and stakeholder feedback report MosaicLab; 2017
Barwon Downs Monitoring Program – monitoring review Sinclair Knight Merz, 2012
72 Supporting documents Author, Year
Barwon Downs Monitoring Program – stage 1: field investigations and monitoring program scope Sinclair Knight Merz, 2013
Barwon Downs Monitoring Program – review of conceptual model and numerical model boundaries Sinclair Knight Merz, 2013
Barwon Downs vegetation monitoring – vegetation monitoring report Jacobs, 2014
Field investigations report – installation of new monitoring assets Jacobs, 2014
Barwon Downs hydrogeological studies 2015/16 – recharge rate assessment Jacobs, 2016
Barwon Downs groundwater dependent terrestrial vegetation investigations – understanding tree water use Jacobs, 2016
Barwon Downs vegetation survey report Jacobs, 2017
Boundary Creek aquatic ecology investigation Jacobs, 2017
Barwon Downs Technical Works Program – Integration report Jacobs, 2017
Barwon Downs Numerical model calibration report Jacobs, 2018
Low flow recommendations for Boundary Creek Jacobs, 2018
Yeodene Swamp study Jacobs; 2018
Predicted impacts and assessment report Jacobs; 2018
73