Recently there was a large fish kill in a lake at Beachmere near Bribie Island. Residents noticed thousands of fish floating on the surface of the lake. The fish had died overnight. Many species were affected and those identified include mullet, mangrove jack, bream, whiting and flathead. Recent building works at the nearby sewage pumping station are suspected.
A marine biologist who lives near the lake reported that a pipe from the building site was pumping approximately 2 litres of ground water per minute into the lake. The ground water is not contaminated with sewage but unfortunately it’s rich in sulphur compounds. These compounds consume oxygen forming the ‘rotten egg gas’ or sulphur dioxide which residents reported smelling. The lake is not flushed daily by the tide so the smelly water stays there for a while. The ground water from the building works is likely to be consuming the oxygen in the lake, leaving none for the fish and subsequently causing their death.
Ground water in the estuarine regions of southeast Queensland are often rich in sulphur compounds. When they are undisturbed they do no harm. When they are pumped into water that is poorly flushed fish kills do occur.
Poor planning appears to be responsible here. If the ground water had been pumped into a well flushed system then it is unlikely that such as large fish kill would have occurred.
Pumping out anoxic ground water into adjacent waterways is a common practice in southeast Queensland. We’ve seen it being done on waterfront developments on the Gold and Sunshine Coasts. Council should have foreseen the effects of this action.
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