Amid all the fanfare over the danger from a potential mine tunnel blowout near Leadville, scant attention has been given to what might be the most long-lasting fallout: the health of the Arkansas River fishery.
The Arkansas perhaps has suffered most from Colorado’s checkered mining legacy, languishing for years in the backwash of heavy-metal pollution from the far-flung Leadville district. Now, just as the river is nearing full recovery following a 1992 Superfund cleanup, comes a threat to these gains as well as future improvements.
Under a worst-case-scenario blowout, trout could be lost for miles downstream.
In case you missed it, the trouble comes from the Leadville Mine Drainage Tunnel, a key link in that 1992 revival.
The tunnel carries Evans Gulch water leeching from rock and disturbed soil to a treatment plant near the river. That’s where toxic heavy metals such as zinc and cadmium are removed.
A partial tunnel blockage caused an estimated 1 billion toxic gallons to collect in the tunnel and the rocks above. Officials fear mounting pressure could cause the tunnel to burst, threatening the lives of local residents while polluting domestic water supplies for Aurora, Colorado Springs and Pueblo.
More recently, the water backup has reached an elevation that created seeps of toxic water through fissures down the separate California Gulch drainage to the south. A second 1992 treatment plant here at the Yak Tunnel also contributed to the river cleanup.
This latest seepage, flowing below the plant, already has reached the river.
Greg Policky, area biologist for the Colorado Division of Wildlife, this week will begin testing to determine whether this leak has caused damage to the aquatic resource. But it’s what might happen next that has him most worried.
“A blowout could be like the one at the Yak Tunnel,” Policky said of a 1985 event that turned the Arkansas River a dirty orange all the way to Pueblo Reservoir and precipitated the Superfund action.
The calamity caused the wildlife agency to launch a study that delivered a startling discovery.
“That’s when we found a cadmium accumulation in internal organs kept fish from living past 3 or 4 years old,” Policky said of the condition that held the river’s resource in a sort of extended death grip.
Since the cleanup, recovery has been remarkable. A dominant brown trout population now lives twice as long, with a considerable gain in size.
“We also have a more diverse and abundant bug life, more food resources right down to the development of plants,” the biologist said.
This recovery is reflected in a surge in fishing-based recreation along every segment of the river. Nowhere is this more evident than in the upper reaches near Leadville. Once devoid of fish life, this part of the Arkansas now is the center of expanded public access and stream improvement projects.
“We’ve added a lot of access and continue to do so,” Policky said of conservation easements being obtained in the Hayden Flats area as part of settlement agreements from old mining abuses. The biologist also has designs on a series of habitat initiatives on the upper river as early as 2009.
The favorable result can be measured both in added hours of recreation and a healthy boost to the local economy.
“We don’t want a water quality issue to jeopardize what we’ve accomplished or the things we have planned,” Policky said.
Along with those nervous residents beneath the Leadville tunnel and half a million downstream water users, Policky hopes solutions can be found, and soon. A lot of anxious anglers, eager for the upcoming season, feel the same.
Charlie Meyers: 303-954-1609 or cmeyers@denverpost.com
