Assessment finds stormwater flow into Karaaf underestimated

AN INDEPENDENT assessment has found the Surf Coast Shire underestimated the amount of water that would flow from Torquay North developments into the Karaaf Wetlands, but the shire has pledged to reduce the flow of this water to stop any further environmental damage.

Commissioned by the shire, the two assessments – about the environmental conditions and the stormwater system, respectively – came in response to years of concerns about the impact freshwater runoff from new housing is having on the naturally saline Ramsar-nominated wetlands.

The assessments conclude stormwater from Torquay North is having an adverse impact on the Karaaf Wetlands, and many of these impacts have occurred only in the past few years.

Other factors include overland water flows, freshwater and tidal inflows from Thompson Creek, and climate change.

Shire chief executive offcer Robyn Seymour said the assessments revealed the shire’s master planning of the stormwater network more than 10 years ago focused on managing peak flow rates rather than total volume.

“Therefore the plans underestimated the amount of water that would be generated from north Torquay developments and did not identify the potential for it to affect the vegetation in the Karaaf Wetlands

“We are committed to learning from and addressing this.”

This concurs with an independent study in October 2021 commissioned by The Sands Owners Corporation, which found the volume of stormwater that needed to be managed had been underestimated by 25 per cent.

“We will also begin implementing some of the actions identified in the North Torquay Constructed Wetland Assessment to improve the effectiveness of the constructed wetlands,” Ms Seymour said.

“We need to make sure that any actions we or others take are effective. This means that all agencies and partners will also need to gather more information before making any decisions that might change the way the Karaaf Wetlands functions.”

Councillors received the assessments at their meeting on Tuesday this week.

Shire mayor Libby Stapleton said the Karaaf Wetlands were a complex and changing environment as well as a culturally significant landscape.

“We have more to learn about how much water is needed by the Karaaf, from what sources, at what times and in what climatic conditions to ensure it is healthy.

“The reports have helped us discover that the quality of stormwater needs to be improved and the volume entering via The Sands lakes system needs to be reduced.

“This work will take time but we are focused on achieving the best result for the Karaaf.

“We are grateful for our community’s activism and care for the environment.”

An alternative water scheme for the Surf Coast hinterland could be one solution to the issue.

Announced by Barwon Water earlier this week, the scheme would involve diverting stormwater before it reaches the Karaaf and mixing it with Class A recycled water from the Black Rock Water Reclamation Plant, and pumping this water to the hinterland including the Thompson Valley to support high-value agriculture in the area.

The shire will hold an open information sessionabout the assessments at the council offices in Torquay North on Thursday, October 27 at 6pm. There will also be an option for people to join the session online.

For more information, head to surfcoast.vic.gov.au/Karaaf