Environmental Protection Agency officials said Tuesday that the toxins leaking out of the Leviathan Mine can probably never be stopped, but they don't think downstream users in Douglas County will be hurt.
EPA representatives made their comments during a tour of the mine site, located in Alpine County, Calif., about 25 miles southwest of Gardnerville. The mine operated intermittently between the 1860s and 1962 and has been discharging toxic runoff into the surrounding area. EPA officials are considering making it a Superfund site.
California water quality officials have been trying to treat the acid drainage at the mine site, and they are enthused with the results. They said they will continue a three-pronged approach to the problem: a permanent system to treat the runoff, a system for collecting the ground and surface water that comes through the site and an effort to prevent the water from becoming contaminated at all.
Still, some runoff will probably escape.
"It is very unusual to take a mine like this and completely eliminate the problem," said Harold Singer, executive officer of California's Lahontan Regional Water Quality Control Board. "We expect to be out here for a long, long time."
"We won't catch every last drop of contaminated water, but we think we can do a good enough job to protect the ecosystem and any people that would be using the resources downstream," said Kevin Mayer, Superfund project manager.
Keith Takata, director of the regional Superfund division, said a Superfund designation won't necessarily carry impacts like mandatory disclosures on real estate transactions for Carson Valley residents because the agency's immediate focus would be the mine site.
"We will evaluate downstream impact, but we're only going to be looking at water quality," said Takata. "We're not looking at the land area above the rivers. Based on what we know now, I think it's extremely unlikely that we'll be taking active remediation way downstream in Nevada."
The Lahontan Regional Water Quality Board began cleanup efforts in 1982 after agreeing to a settlement with ARCO, one of the previous owners. The mine site covers about 400 acres.
Part of the original mine site has been filled in and ponds have been built to detain the toxic runoff, but the ponds have overflowed in past winter.
Water running through the mine site turns sulfur into sulfuric acid, which dissolves minerals in the rocks and produces a soup that is toxic to wildlife. Overflows have spilled into Leviathan Creek, which empties into Bryant Creek, a tributary of the Carson River's east fork.