SUMMIT COUNTY — Last summer's spike in zinc and other metals in the Snake River has persisted, spelling more trouble for trout in the polluted stream.

Colorado Division of Wildlife biologists were disappointed by the absence of brook trout when they surveyed a section of the Snake near Keystone last week.

“It’s definitely a step backwards,” said fisheries expert Jon Ewert, who had hoped that the brookies would re-establish themselves after last summer's gully-washing storm that sent a surge of poisonous metals down the drainage.

Since then, concentrations of zinc seeping from the abandoned Pennsylvania Mine high along Peru Creek have remained near double what they were before the storm, at about 1,200 parts per billion, far above levels deemed toxic for trout.

Zinc kills trout even at concentrations that aren't harmful to humans. Levels in the Snake River have long exceeded state and federal limits.

Some scientists studying potential cleanup options for the Snake River believe that the rainstorm last year may have fundamentally changed the drainage from the mine, leading to the chronically higher levels.

Other experts think that the reported increase in zinc concentrations may be related to the way the monitoring data is being analyzed and interpreted by the labs, said Lane Wyatt, a Summit County water-quality expert.

“The zinc levels were a huge surprise,” said Trout Unlimited's Elizabeth Russell, one of the leaders of a task force looking at how to improve water quality in the Snake River. “We didn't think they’d stay that high over the winter.”

Jean Mackenzie of the U.S. Environmental Protection Agency also expected the concentration of heavy metals to fade over time.

“You’d expect it to go lower because of dilution,” she said.

Treatment planned

In a round of electro-shocking last summer, volunteers found two healthy brookies. Ewert said that led him to hope those fish might be the first to re-colonize the Snake after the surge of metals.

This summer’s survey did turn up 44 rainbow trout, part of an ongoing stocking program by Keystone Resort.

“I'm not sure how long rainbows will survive,” Ewert said.

Based on results of another study, the life expectancy of that species in the Snake River can range anywhere from a few weeks to a few months before they succumb to zinc poisoning, depending on the exact location and the concentrations of the dissolved metal.

Ewert marked the rainbows to monitor whether they survive until next year, when he returns for the next round of sampling.

“I don't expect them to survive a year. I seriously doubt it,” he said.

Russell said the task force is considering a potential Superfund listing for the Pennsylvania Mine. The designation might make some federal clean-up money available.

The most likely solution is to build a water-treatment plant at the mine to remove some of the metals.

Some recent tests have included so-called tracer samples to determine how the water is flowing through and out of the mine. Russell said that work will continue.

Additionally, state mining officials plan to open some of the sealed entrances in an attempt to get a better understanding of the underground workings.

Next summer, they may even explore the lower portal, the source of the seepage into the Snake, Russell said.

Monitoring has intensified during the past year, according to Mackenzie. A new weather station near the mine could help determine if fluctuations in metals are tied to precipitation.

Next month, EPA scientists and other experts will bring a mobile lab to the site to sample the wetlands and tailings piles below the mine to see if those are contributing to the contamination of Peru Creek and the Snake River, Mackenzie explained.

The task force will also look at whether it’s feasible to divert some of the water flowing into the mine. That could reduce the amount of treatment needed.

Bob Berwyn can be reached at (970) 331-5996, or at bberwyn@summitdaily.com.