Sediment likely culprit in Colorado River fish kill | AspenTimes.com

Sediment likely culprit in Colorado River fish kill

Post Independent staff report
Aspen, CO Colorado

GLENWOOD SPRINGS – A heavy monsoon downpour Tuesday night flushed a large amount of debris and sediment into the Colorado River above Dotsero, likely contributing to a large fish kill, Colorado Parks and Wildlife officials said Friday.

Workers at the Shoshone Hydroelectric Power plant in Glenwood Canyon first reported seeing dead fish near the plant on Wednesday.

By early Friday morning, Colorado Parks and Wildlife officials estimate that thousands of dead fish had appeared along the river, all likely succumbing to the large amount of mud, silt and debris that washed into the water.

“I have never seen the river this full of debris,” said Perry Will, area wildlife manager.

This summer, many fish in western Colorado have been stressed by low flows and high temperatures brought on by drought-like conditions. Wildlife managers believe the additional stress from debris and sediment swept into the rivers proved excessive for these fish.

“Many of the fish we inspected had fine silt on their gills,” said Kendall Bakich, aquatic biologist for Colorado Parks and Wildlife in Glenwood Springs. “At this point, we believe that this is what led to the mortality, but we are continuing to investigate.”

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Wildlife officials say that some dead fish will continue to travel down river and may be visible to anyone traveling along the river; however, they advise that the fish all died several days ago and they do not expect continued fish mortality.

Most of the fish that were killed were both native and non-native suckers, along with a few trout. According to Bakich, suckers are more susceptible to heavy debris and sediment in the water because they are bottom dwellers.