Small fish kill reported in Avon | VailDaily.com

Small fish kill reported in Avon

Cliff Thompson

The bodies of approximately 20 small brown trout were discovered in pools below the Avon wastewater treatment plant’s outflow, but wildlife officials say it’s not clear what killed the fish.

“It’s a head scratcher,” said Pete Walker, a fish pathologist with the Colorado Division of Wildlife.

The dead fish were discovered Saturday by fisherman Bo Dwyer, 13, along a 100-yard stretch of the river.

Operators of the Avon wastewater treatment plant checked discharge records and said there were no problems reported.

“We don’t think it’s related to the operation of the wastewater plant,” said Bob Trueblood, wastewater operations manager for the Eagle River Water and Sanitation District, which operates the plant.

The small fish kill follows by four days a 500-gallon spill of raw sewage into the river that occurred at the same spot, when a sewer main backed up. That main had been cleaned in August, Trueblood said.

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The spill occurred over a four-hour period, Dec. 2. Wildlife and wastewater officials expressed doubt that the spill could have killed the fish because the river has a flow of 70 cubic feet per-second – enough to dilute the spill.

“I don’t believe it’s related to the operation of the wastewater plant, Trueblood reiterated.

Those investigating the kill also examined activities of a crew demolishing a bridge in the area, but that examination was inconclusive, they said.

Brown trout spawn in the autumn and the stress of spawning can cause mortality. But the spawning season is largely over and the bodies of the fish recovered appeared to be in good shape, said Bill Andree of the Division of Wildlife.

Fisherman Dwyer collected several of the fish and took them to nearby Fly Fishing Outfitters where the fish were frozen for possible later examination.

Dwyer said he saw another dead fish several hundred yards upstream of where he discovered the other dead fish while he was fishing near the Avon Road Bridge.

One of the fish he caught had a white cloudy fungus on its dorsal fin, he said.

Pathologist Walker said that without having some indicators of what caused the kill, finding what caused the fish to die is “worse than finding a needle in a haystack.”

Cliff Thompson can be reached at 970-949-0555 x450 or cthompson@vaildaily.com