State wildlife biologists are trying to determine how hundreds of trout found floating in a half-mile stretch of the Ogden River died.
About 200 fish, mostly brown trout, have been found dead in the water since Monday between the Ogden water treatment plant and the Oaks Restaurant, said Jerry Wiechman, fisheries biologist for the Utah Division of Wildlife Resources.The fish ranged in size from 5 to 18 inches.
Wiechman said the DWR cannot yet pinpoint what killed the trout, but he suspects it was some sort of chemical toxin. He said biologists detected no odor or film on the water that could point to a specific toxin.
"It looks as though some sort of a chemical hit them, but we don't know what it was," he said.
Mike Pribbanow, an angler from North Ogden, said he was fishing on the river Wednesday and saw many dead fish and also live fish that appeared to be suffering from some ailment.
"There were dead and dying fish all over," he said.
Wiechman said biologists collected dead fish and took water samples Monday.
The DWR has ruled out chlorine poisoning and low oxygen levels in the river, Wiechman said.
Ogden's water treatment plant has been closed since September for renovation. Paul Hodson, Ogden City water utility manager, said water being supplied to the city is now coming from wells and does not go through the plant.