Colorado Parks and Wildlife is investigating Johnstown officials after their attempt to treat an algae outbreak left nearly 1,000 fish dead.
The Greeley Tribune reports that Parks and Wildlife spokeswoman Jennifer Churchill says a worker put a copper sulfate into the town’s reservoir this summer to treat the algae. She says chemical ended up suffocating 972 fish.
The National Pesticide Information Center says copper sulfate can cause sudden plant death, causing fish to suffocate because of depleted oxygen and clogged gills.