GARDNERVILLE, Nev. - Environmental officials are hopeful that control efforts combined with a mild winter may prevent the overflow of a toxic stew from an abandoned Sierra sulfur mine for the first time in three years.
Evaporation ponds designed to contain the poisonous runoff at Leviathan Mine have routinely overflowed in spring, spilling heavy metals and other pollutants into the streams that feed the Carson River.
But officials are keeping their fingers crossed that won't happen this year.
As recently as February, U.S. Environmental Protection Agency officials said an overflow was virtually inevitable.
But treatment of mine drainage conducted over late summer, some pumping conducted at the site in March and mild weather late in the winter have combined to leave experts more optimistic.
''We came close but its looking pretty good,'' said Kevin Mayer, project manager for EPA's Superfund program.
Heavy storms in mid-winter left Mayer with little optimism an overflow could be avoided. But a warm spring with little precipitation coupled with the pumping of some 500,000 gallons of clean water trapped above the frozen surface of the ponds improved the situation dramatically.
''We're not ready to say (overflow) is not going to happen yet but we're very optimistic,'' said Harold Singer, executive director of California's Lahontan Regional Water Quality Control Board. ''We've been pretty lucky with the weather and frankly that's the bottom line.''
Roughly 1 million gallons of storage capacity remains in the ponds. With most of the snow melted and the days growing longer and warmer, officials are hopeful evaporation will offset continued flow of contaminated groundwater into the ponds.
Leaders from Douglas County and other downstream water users, including the Washoe Tribe, worry over the long-term impacts of contaminants flowing into tributaries of the Carson River.
A rust-colored stew of acids and heavy metals has obliterated aquatic life in Leviathan Creek, and many fear the pollution could ultimately pose a serious threat to the river.
A proposed Superfund site, the mine 25 miles southwest of Gardnerville in California's Alpine County produced copper sulfate from 1863 until 1872. It was reopened for a six-year period to produce sulfur beginning in 1936.
From the 1950s to early 1960s, open pit mining was used to extract sulfur until the mine was finally shut down in 1962.
Mayer said a final decision on whether to list Leviathan Mine as a Superfund site status reserved for the most polluted places in the nation could come within two weeks.
A Superfund designation would free up more federal money for mine cleanup and also make the Atlantic Richfield Corp., which acquired the mine from the Anaconda Corp. in 1978, liable for cleanup costs.
Mayer is hopeful the Lahontan board can begin treatment of mine drainage no later than July, boosting the amount treated from the 4.5 million gallons done last September and October to up to 12 million gallons this summer.
That would make an overflow next winter much more unlikely.
''Things have worked out very well this year but not so well that we want to get so close next year or any other year,'' Mayer said.