Drinking water quality for the public system that serves all of Assumption Parish has remained safe despite fish kills due to oxygen depletion in Bayou Lafourche, officials said Wednesday.
Assumption Parish officials said this week that fish kills were reported around Lake Verret and in Belle River and Bayou Lafourche, the drinking water source for the parish.
Louisiana Department of Wildlife and Fisheries officials said Wednesday that such fish kills are common after hurricanes.
Since Hurricane Isaac passed, fish kills also have been reported in other parts of southeast Louisiana, including Blind River in St. James Parish, Lac Des Allemands in St. Charles Parish, the Amite River near the Diversion Canal and in Livingston Parish waterways between Head of Island and Springfield.
“We never fell out of compliance,” said B.J. Francis Jr., general manager of Assumption Parish Water Works District No. 1, which serves more than 20,000 people.
Francis said that when he checked Bayou Lafourche between Donaldsonville and the water works plant Wednesday, he saw no other fish kills.
Francis said the Bayou Lafourche Freshwater District also helped by pumping additional fresh water into the bayou from the Mississippi River.
Francis said the fish kill was not large one.
In a statement last month, Wildlife and Fisheries officials said heavy rain across south Louisiana can cause fish kills through two methods.
Rainfall may carry organic material into bayous and canals connected to lakes. That material can consume dissolved oxygen in the water and suffocate aquatic life.
Fish kills also can be caused by the rapid mixing of warm oxygenated water and cooler, anoxic water at lower levels in the water column, wildlife officials said. In some instances, once mixed, the water can no longer support underwater life.
Mike Wood, director of inland fisheries for Wildlife and Fisheries, said officials are investigating the fish kills after Isaac and believe they are due to rapid mixing of water, including incidents in Bayou Lafourche, Amite River and Blind River, as well as in Livingston Parish.
“All of that was exposed to severe winds and lots of floods that mixed it too rapidly. That is what actually causes these fish kills,” Wood said.
He said the oxygen loss does not pose a drinking water risk because the systems using water in Bayou Lafourche employ purification processes before the water is distributed.
Wood said that depending on the amount of oxygen loss, a variety of marine species can be killed, but the populations recover.
“It is a fact that our coastal fisheries are exposed to these storms and have been since time began, and they came back then and they’ll come back from now on,” he said.
Residents who encounter a fish kill are encouraged to call (800) 442-2511 immediately to report the incident, wildlife officials said.