SUMMIT COUNTY " A surge of sediment and heavy metals likely killed a number of fish in the Peru Creek tributary after recent heavy rains washed through the area.
"We might have lost a lot of the fish in that drainage," said Tom Kroening, a local wildlife manager for the Colorado Division of Wildlife (CDOW), after a wave of pollution on Aug. 3 discolored the river for several hours.
Forest Service officials reported chocolate-colored water in the vicinity of Keystone's Snake River snowmaking diversion early in the afternoon. Kroening said he started hearing reports from citizens about dead and dying fish about that same time.
Other area residents called the Summit Daily News and left reports of "dozens" of dead fish in the Snake River in the vicinity of the golf course.
Even after the brown color disappeared, Kroening said the Snake River ran a milky blue-gray for several more hours, perhaps a visual indication of the pollution from Peru Creek.
With the water running swiftly, Kroening said it was hard to get an accurate count of dead fish in the Snake River. Often after a fish kill, CDOW collects fish and sends them to a lab for testing to determine the exact cause of mortality.
Kroening said in this case, it was difficult to collect fish, and the cause seemed directly traceable to a surge of polluted water from Peru Creek. No samples were collected for analysis, but Kroening said the incident points out the need to address heavy metal pollution in Peru Creek for the sake aquatic health in the Snake River.
The timing of the fish coincided with high-flow readings from several automated gauges along the Snake, when flows doubled in a short period of time.
"It seemed pretty straightforward as to what happened," Kroening said.
Most of the fish in the Snake River between Keystone and Dillon Reservoir have been stocked by CDOW. Concentrations of toxic metals in the stream " primarily zinc " exceed state-set limits as set under the federal Clean Water Act. The river does not support a self-sustaining fishery, but the metals don't present much of a human health risk, according to local water quality officials.
The abandoned Pennsylvania Mine, near Peru Creek, has been pinpointed as one of the primary sources of metals in the basin. A broad-based task force has been looking at the health of the Snake River for several years. Recent steps include yet more studies of the pollution, as well as some preliminary design work on a possible treatment system.
Kroening spent several hours during and after initial reports of discolored waters trying to trace the source. He observed conditions in the river near the Keystone Mountain House base areas, as well as in the vicinity of the River Run gondola.
Water coming in from the North Fork tributary (the drainage near U.S. Highway 6, toward A-Basin) was clear, as was the main stem of the Snake coming from Montezuma. By making visual observations in the different drainages, he was able to determine that Peru Creek was the source of the discoloration and possible surge of heavy metal pollution.
Reports from other observers along Peru Creek seemed to confirm his observations, he added.