A rare outbreak of toxic algae on the Ohio River that has stretched more than 600 miles is starting to wind down.
Drinking water plant operators along the river say what happened should serve as a warning to cities that get their supply from lakes, rivers and manmade reservoirs.
The algae bloom first detected in the middle of August made its way from Wheeling, West Virginia, and past Cincinnati and Louisville, Kentucky.
Toxins produced by the algae haven’t tainted any municipal supplies, but cities did spend more money treating their water.
Researchers say heavy rains in the early summer washed algae-feeding pollutants into the river and that a dry late-summer made conditions just right for the outbreak.
Copyright 2015 The Associated Press.