Trout wiped out in Keystone river
Vail, CO Colorado
SUMMIT COUNTY ” Standing hip-deep in the swift water of the Snake River near Keystone, it’s hard to see how a fish wouldn’t like it here. At first glance, it’s a pristine mountain stream, lined with willows and glacier-polished boulders.
But the water has a slight tinge to it, still milky green from two recent storms that may have sent a surge of toxic heavy metals, as well as a killer load of silt, rushing down the stream.
“It doesn’t look quite right,” says local angling guide Dale Fields, pointing out where a layer of fine brown mud has settled on the gravely banks of the river.
Fields, who has been fishing local waters for more than 20 years, thinks the rainstorms in early August unleashed a heavy load of sediment that choked most of the fish in this section of the Snake River.
Hundreds of fish may have died following the pair of storms, Fields estimates, and biologists this week searched for survivors in a 500-foot section of the stream.
Volunteers used long-handled electric probes and nets to trap the fish. If a probe passes within a few feet of a fish, it stuns them, and they float to the surface where they can be netted, then measured and weighed.
The idea was to scour every inch of river bottom and every embankment and shady hole where a flashy rainbow or a speckled brook trout might have been hiding.
Several weeks ago, a similar survey in the same stretch of river yielded about 40 to 50 fish, Ewert says.
But this week, only two small brook trout were found.
Colorado Division of Wildlife aquatic biologist Jon Ewert said he thinks the toxic metals killed many of the fish. If the fish were already stressed from ongoing exposure to metals, a sudden spike could have been enough to kill, he said.
But Fields says the fish died too fast ” within a few hours of the storm ” to pin the blame on pollution from abandoned mines upstream. Because the river turned brown as chocolate milk, a heavy load of silt is the more likely cause, he said.
But at this point, it’s almost impossible to know for sure, since none of the dead fish were recovered and sent to a lab for analysis, where a close examination could reveal concentrations of metals in fish tissue. Nor did local water quality officials take water samples during the runoff events, so there’s no way to know for sure whether there was a sudden surge in the concentrations of metals.
Whatever the exact cause, it appears that the rainbow trout population has been completely wiped out, though Keystone plans to restock the river with fish at the end of August, in time of the Labor Day weekend.
“It definitely indicates there was … a shock to the river,” Fields says.