Acid and heavy metal drainage leaks from many of the estimated half a million abandoned mine sites across the nation, including some 17,000 in Colorado. In this 2004 photo, contaminated water from the Dinero mine runs into a series of man-made ponds before it reaches the Lake Fork of the Arkansas River. Post file

By The Denver Post - Colorado’s two U.S. senators moved closer Wednesday to winning passage of legislation that would allow volunteers to clean up abandoned mines without risking fines.

The bill from Sens. Wayne Allard, R-Colo., and Ken Salazar, D-Colo., passed the Senate Committee on Environment and Public Works. Their “Cleanup of Inactive and Abandoned Mines Act” will advance to a vote of the full Senate. It’s not clear when the Senate will take up the bill, however.

Thousands of abandoned hard-rock mines - some dating to the 1800s - are poisoning headwater streams across the West with acid drainage and toxic heavy metals that kill fish and sometimes get into drinking-water supplies.

Currently, citizens, local governments and businesses that volunteer to clean up abandoned mine sites could face fines and legal liability if they don’t bring the mines up to exacting clean-water standards specified by federal law.

The Allard-Salazar bill would create an exemption for “good Samaritan” volunteers, waiving clean-water penalties as long as some degree of pollution reduction occurs at mine sites.

“This is the biggest step for the good Samaritan bill in nearly a decade,” Allard said. “Our legislation will allow these contaminated, abandoned mines to be cleaned up free of taxpayers’ expense.”

“Good Samaritans who want to clean up Colorado’s numerous inactive or abandoned mines should be able to do so,” Salazar said. “This bill will promote the cleanup of these sites under the guidance of the appropriate interests - the EPA, the states and the public.”

Critics of the bill, including some conservation groups, say it could allow mining companies to be designated good Samaritans and re-open old mines without being subject to strict pollution limits.

But proponents say mining firms often have the equipment and know-how to do a good job of cleaning up old mines.

Other versions of the legislation, including a proposal to the Bush administration, are less accommodating to the mining industry.