Karaaf problems not solved by Thompson Creek opening: review

A REVIEW of Torquay waterways has found that opening the Thompson Creek estuary would fail to improve the health of the deteriorating Karaaf Wetlands.

Corangamite Catchment Management Authority and Surf Coast Shire Council had partnered to test theories aimed at reducing impacts of stormwater inflows on the Karaaf Wetlands, with authorities to continue investigating recovery strategies for saltmarsh vegetation.

Environmental issues at Karaaf Wetlands have become of increasing concern in recent years as nearby housing development at Torquay North has increased volume of freshwater in the usually saltwater system leading to vegetation dieback and weed growth.

The recently concluded review found that opening the estuary at Point Impossible would not flush more stormwater out of the wetland to its west nor increase the salinity of the local groundwater system.

CCMA Estuaries and Environmental Water Manager Jayden Wooley said opening estuaries was an extreme measure the authority preferred to use only when built infrastructure or flooding was at risk.

“Most estuaries in the Corangamite catchment are intermittently open/closed estuaries, which close from time to time as part of a natural process. Maintaining this natural intermittence is vital to support the estuarine ecosystems, including the protection of the unique plants and animals that thrive in these systems.”

“Because of this, artificial estuary openings are minimised in the Corangamite region as there is generally no environmental benefit, and artificial openings can put ecological values at risk. This approach has historically been strongly supported by research and the findings of this study further support this.”

The Karaaf Wetlands Estuary Mouth Assessment had followed a September 2022 report from the shire, which suggested artificially opening the Thompson Creek entrance could be a “useful tool” to minimise future dieback events.

Surf Coast Shire Council placemaking and environment general manager Chris Pike said the review offered “valuable information” to agencies despite rejecting the earlier report’s idea.

“It is part of the further work we identified was required following the environmental assessment commissioned last year.

“It provides us all with another key piece of data which will greatly assist with council’s work in developing effective short and long-term options to reduce the volume of stormwater entering the Karaaf Wetlands.”

Findings of the Karaaf Wetlands Estuary Mouth Assessment are available online at the CCMA’s Knowledge Base eLibrary.