Contractors for Lahontan Regional Water Quality Control Board expect this to be a record summer for treatment of acid mine drainage at the Leviathan Mine superfund site in Alpine County.

Treatment prevents toxic discharges from the mine to Leviathan Creek, Bryant Creek, and the East Fork Carson River.

As a result of the highest amount of rain and snowfall since 1995, acid mine drainage from ponds at Leviathan Mine threatened to overflow in April. The Water Board mobilized a contractor three months earlier than normal to prevent overflow.

From April through May, the Water Board conducted spring treatment of the AMD to prevent discharge of untreated water. That operation treated more than 7 million gallons of AMD.

Summer treatment operations that just begun are expected to treat an additional 10 million to 15 million gallons of AMD, potentially making it the greatest amount of toxic mine drainage treated by the Water Board at the site.

Leviathan Mine is an abandoned sulfur mine five miles east of Markleeville and six miles west of Topaz Lake that was owned and operated by the Anaconda Copper Mining Company in the 1950s and 1960s. California acquired the mine in 1984 to clean up water quality problems caused by the mining operations. The Water Board completed a pollution abatement project at the mine in 1985, and since 1999 has continued to actively treat waters discharged from the mine site.