Unplugged: Illegal estuary opening continues Thompson Creek drama

FLOODWATERS in the Thompson Creek estuary near Breamlea are receding following the alleged illegal opening of the estuary mouth.

Corangamite Catchment Management Authority (CMA) estuaries and environmental water project officer Hayley Vinden repeated a warning made earlier this month that artificially opening an estuary without undertaking an environmental risk assessment can have a detrimental impact on fish, birds and wildlife.

“Thompson Creek is an intermittently open/ closed estuary, that was closed at the time due to a natural sand berm forming,” Ms Vinden said.

“The water in the estuary has two layers; an oxygen-rich freshwater layer on top and an oxygen-poor saline layer on the bottom.

“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, which can result in fish kills.”

Unauthorised openings of the estuary can result in fines and/or imprisonment.

The opening, which is believed to have taken place sometime over the weekend (the photo with this story was taken by James Walsh on Monday morning), followed another illegal attempt to open the estuary last month.

Before the alleged illegal opening, property owners affected by the flooding had made requests to various authorities, including the Surf Coast Shire, to open the mouth to the sea to reduce flood levels on their properties and surrounding roads.

Russell Mumme, who lives on the northern banks of the estuary and whose driveway was inundated by the floodwaters, said he had contacted the Surf Coast Shire and Corangamite CMA about opening the estuary mouth. He said the water levels this year were notably higher than when the estuary mouth was last opened artificially in 2016.

Before the estuary was opened, the shire’s general manager for governance and infrastructure Anne Howard said the estuary had been left closed because of the significant environmental benefits.

“We are liaising with the City of Greater Geelong, Corangamite Catchment Management Authority, Great Ocean Road Coast Committee, Parks Victoria and Department of Environment, Land, Water and Planning on the situation,” she said.

She said a range of agencies could apply for a permit to open the Thompson Creek estuary mouth “if there was a clear need to do so”.