Dennis Cooper said he was born and raised near present day Lake El Reno.
“I played here before the lake was here,” he said.
In that time, he's seen plenty of changes but he said fish kills are a first.
Officials with the Department of Wildlife Conservation first got reports of the problem on Saturday.
“The assistant city manager with El Reno, they had some reports of dead fish from anglers,” said Keith Thomas, fish biologist with the Department of Wildlife.
Thomas said the problem can be traced back to blue green algae.
He says it's something he's seen before throughout the state.
“El Reno City Lake is just the tip of the iceberg, I guess all the reservoirs in our state are starting to show their age,” Thomas said.
They're filling in with silt and runoff; a perfect area for algae to bloom.
Thomas said that, coupled with the extreme temperatures, create the fish kills.
Biologists say until further notice, there is no swimming in the lake but fishing is permitted.