Barwon Water has submitted its proposed remediation and environmental protection plan for Boundary Creek, Big Swamp and the surrounding environment to Southern Rural Water (SRW) following 18 months of scientific studies, advice from independent technical experts and valuable community feedback.
Managing Director Tracey Slatter said the proposed plan was a positive step in the process to remediate the confirmed impacts from historic management of groundwater pumping of the Barwon Downs Borefield, which was last used in 2016.
Confirmed impacts include the reduction of flows in Boundary Creek and the subsequent activation of acid sulfate soils in Big Swamp, resulting in acidic water discharging to Boundary Creek downstream of the swamp.
Eight key principles underpin the proposed plan and include continuing an open and transparent relationship with Traditional Owners, the community and key stakeholders during its implementation and not jeopardising the recovery of water levels in the Lower Tertiary Aquifer (LTA).
The LTA water level is recovering through rainfall recharge and is protected by the low Permissible Consumptive Volume (PCV) for the borefield, which was reset from 20,000 megalitres per year to 239 megalitres per year by Minister for Water the Hon. Lisa Neville MP in July.
About the remediation plan
Barwon Water’s proposed remediation plan will involve direct action and constant monitoring and adjustment to ensure improvements to water flows and quality, vegetation and ecology in Boundary Creek and Big Swamp.
Ms Slatter said the proposed plan would focus on the continual wetting of Big Swamp through controlled release of water to Boundary Creek and the installation of hydraulic barriers to maintain surface water and groundwater levels within Big Swamp.
The aim of this work is to improve water quality in Big Swamp, stabilise the acidification process that takes place due to the drying and wetting of the acid sulfate soils in the area, and reduce the risk of acid flush events in Boundary Creek in the long-term.
“We will work closely with independent technical experts throughout every stage of the proposed remediation plan,” Ms Slatter said.
“We will continue environmental monitoring, which includes water quality sampling, water level and flow monitoring, vegetation surveys, and sediment and macroinvertebrate sampling.
“If we find further action is needed, the proposed remediation plan can be adapted to incorporate appropriate contingency measures, as advised by technical experts, which could include treating water leaving Big Swamp.”
Ms Slatter said once the remediation strategy was implemented, it was forecast that low pH events would diminish during the next decade and that the ecological values of the swamp would improve.
“This is a carefully considered plan, based on significant community and technical input,” she said.
The proposed plan will also investigate whether or not other areas within the regional groundwater system have been impacted.
Barwon Water will share the outcomes of the assessment of these other areas with Southern Rural Water to determine what remediation steps need to be taken if environmentally significant impacts from historical management of groundwater pumping is confirmed.
The proposed remediation plan responds to the requirements of a Ministerial Notice issued to Barwon Water under section 78 of the Water Act 1989.
Thanks to the community
Ms Slatter thanked the dedicated community and stakeholder remediation working group and its nominated independent technical experts for providing valuable advice into the development of the proposed remediation plan over an 18-month period.
The group, which met 10 times, was comprised of Traditional Owners, representatives from LAWROC, Corangamite Catchment Management Authority (CCMA), Colac Otway Shire Council, Environment Victoria, Upper Barwon Landcare Group, Boundary Creek landowners and other interested community members.
The three nominated experts were Dr Darren Baldwin (independent consultant), Dr Vanessa Wong (Monash University) and Professor Richard Bush (Monash University).
In addition to engaging with the working group, Barwon Water hosted five information sessions in Winchelsea, Birregurra and Colac to provide the community with updates on the project and an opportunity to ask questions and have input into the process.
Southern Rural Water will consider the proposed plan with feedback to Barwon Water expected in late February. For more information on this, please visit: www.srw.com.au/barwondowns