The Causeway gates are open at Bargara as a king tide flushes Moneys Creek with sea water.
The abnormal high tide is caused by this week's super moon and the effects of Tropical Cyclone Oma.
A Bundaberg Regional Council spokeswoman said the Moneys Creek tide gates were generally opened on a monthly basis.
“We do that to coincide with the high tides and obviously at the moment they’re getting a great flush,” she said.
“The primary purpose of that flushing is to allow fish movement and also to provide some flushing for that upstream area.
“The fish do like to go between the two water bodies. Any sort of movement of water between two water bodies assists in improving water quality.
“The risks of not having any exchange there is that the water level could get really low and that would increase the risk to marine life.
“It could lead to a risk of algal blooms upstream if the flushing didn’t take place.”
Council’s schedule for the operation of the Moneys Creek tide gate is available on its website.