Estuary opening a threat to wildlife

GOVERNMENT agencies have raised concerns about the illegal opening of the Thompson Creek estuary at Breamlea which could have “detrimental impacts” to wildlife.

The maximum penalty for illegally opening an estuary is a fine of $20,000 or 10 years’ jail.

Corangamite Catchment Management Authority’s (CCMA) estuaries and environmental water officer Hayley Vinden said it appeared a member of the public had attempted to illegally open the estuary to let the creek’s water subside or to allow sea water to enter the estuary.

“Artificially opening an estuary without undertaking an environmental risk assessment can have a detrimental impact on fish, birds and wildlife,” she said.

“Thompson Creek can contain fish eggs and juveniles such as estuary perch. If these are flushed out at the wrong time it can impact on fish recruitment.”

Ms Vinden said Thompson Creek was a closed estuary with low water levels and low catchment inflows.

“The water has two layers: an oxygen-rich freshwater layer on top and an oxygenpoor saline layer on the bottom,” she said.

“If an estuary in this condition is artificially opened, the oxygen-rich surface layer flows out first, leaving behind water with critically low oxygen levels.”

The warning comes after a northern NSW council experienced a fish death event after an estuary was opened last month.

The fish were starved of oxygen as the rapid outflow of water from the estuary reduced oxygen levels.

CCMA said consistent winter rainfall combined with a natural sand berm blocking