"Sunday morning it looked like the number of dead fish was substantially less," said Altus Public Works Director Bob Stephenson. "I think we have turned the corner."
City employees in concert with the Oklahoma Department of Fish and Wildlife added 1,400 pounds of ammonium sulfate to the 130 million gallons of water in the east reservoir.
Stephenson said conditions are so much improved that he will likely later today open the east reservoir, which had been closed to public access since Friday.
Once reopened, he said, it will be completely safe for fishing. The golden algae that produces a toxin deadly to fish is harmless to humans, and the ammonium sulfate used to treat the reservoir will quickly dissipate.
Stephenson said there never was a threat to human health, but the reservoir was closed off simply as a precaution.
He said when he walked the reservoir on Sunday he saw several fish large enough to reproduce that swam away as he approached. This is a good sign of health, he said, since on Friday the fish were lethargic and dying.
"All of us feel we did the right thing," Stephenson said. "It was amazing to see the amount of cooperation we got."
He is especially grateful for the assistance of the Department of Corrections inmates who spent the weekend gathering the dead fish.
The reservoir was not used for water supply during the episode. Stephenson said most of the city's drinking water comes from Tom Steed Reservoir near Snyder, with the reservoir used only in water emergencies.