Boundary Creek remediation plan annual report submitted

Barwon Water has submitted its 2021-2022 annual report for the Boundary Creek, Big Swamp and Surrounding Environment – Remediation and Environmental Protection Plan (REPP) to Southern Rural Water.

Barwon Water Managing Director Tracey Slatter said that the plan was seeing positive progress being made in the improvement in the health of the affected waterways and surrounding environment.

“Along with the ongoing recovery of the aquifer, improved ecological conditions in the swamp and a reduction in the acidity of the water in Boundary Creek, the report highlights our commitment to prepare and implement a decommissioning plan for the Barwon Downs borefield production bores.

“The decommissioning plan has been included as an action in Barwon Water’s draft 2023-2028 Price Submission and is a sign of our intent to continue to remediate the area and not seek to use the borefield as a back-up drinking water source for the region in the future.”

Ms Slatter said the REPP was designed to be adaptive and based on a wide range of technical assessments and investigations, and featured input from experts from various specialist fields and community and stakeholder working group members.

“The Annual Report reflects Barwon Water’s commitment to revise the REPP as new information comes to hand to ensure it remains fit for purpose and minimises the potential for any further harm that could result from the implementation of heavily engineered remedial actions.

“The Annual Report also outlines Barwon Water’s approach and commitment to further progressing the surrounding environment investigation that aims to assess groundwater pumping related impacts within the broader environment and identify if this has led to any environmentally significant adverse effects.”

Highlights from the report include:

• a commitment to prepare and implement a decommissioning plan for the Barwon Downs borefield production bores which has been included as an action in Barwon Water’s draft 2023-2028 Price Submission
• the ongoing recovery and re-pressurisation of the lower tertiary aquifer
• an improvement in the ecological condition of Big Swamp, with no further encroachment of dry vegetation classes since 2019
• water levels within Boundary Creek and Big Swamp have generally been maintained above the top of non-oxidised sediments, thus minimising the risks associated with any further oxidation of the naturally occurring acid sulfate soils
• the use of supplementary flows to help maintain flows within Boundary Creek continues to be an effective mechanism in preventing cease-to-flow events, with no cease-to-flow events reported since April 2020, and
• the average annual pH within Boundary Creek continues to improve with the annual average pH increasing by 1 pH unit compared for the 2020-2021 period.

Ms Slatter again thanked the members of the community and stakeholder working group who have provided valuable advice, oversight and feedback during the development and implementation of the plan over the past four and a half years.

“We remain committed to keeping the local community and key stakeholders informed regarding the progress of remediation and to sharing the findings and outcomes of the plan.

“We thank remediation reference group members for their ongoing contribution to the remediation process and look forward to continuing to work with them over the coming months and years as we implement the plan, share data and adapt the plan based on observed outcomes.”

The annual report and the plan are available to read on Barwon Water’s dedicated project website.

Background

The remediation plan responds to the requirements of a Ministerial Notice issued to Barwon Water under section 78 of the Water Act (1989) due to impacts from historical management of groundwater pumping activities at the Barwon Downs Borefield, which was relied upon heavily during the millennium drought and in 2016 to supplement Geelong’s drinking water supplies.

Confirmed impacts include the reduction of flows in Boundary Creek and the subsequent activation of acid sulfate soils contained within Big Swamp, resulting in acidic water discharging to Boundary Creek downstream of the swamp.