Officials say green water in the Mississippi River is due to food coloring.

According to John Ram with St. Bernard Homeland Security, Chalmette refinery built a new tank and needed to test it for leaks. Ram said the Department of Environmental Quality gave them a permit to test it with green food coloring that is non-toxic or harmful to fish and animals.

Ram said the refinery should be finished flushing it Thursday and emergency responders in St. Bernard Parish were notified of the testing.