In Leadville, Colorado mine run-off laced with toxic levels of cadmium, zinc, and arsenic, is trapped in a blocked mine drainage tunnel, prompting the Regional Administrator of the US EPA to declare that an "uncontrolled, potentially catastrophic release of water to the Arkansas River is likely at some point."

The Leadville Mine Drainage Tunnel, built by the federal government and owned by the US Bureau of Reclamation, is believed to have collapsed, trapping over 1 billion gallons of water underground.  The resulting water pressure threatens to blow out the tunnel walls and has created new springs which are leaking untreated mine run-off directly into the Arkansas River.

The collapsing tunnel has been filling in with rubble for over 30 years. The US Bureau of Reclamation indicated in 1988 that the threat of a blow-out was "significant" with only 77 feet of water built up inside the drainage tunnel.  Today, with 200 feet of water trapped inside the collapsed tunnel, concerns about a catstrophic failure are forcing officials to develop emergency actions, test warning systems, plan for evacuations, and immediatly pump water out of the drainage tunnel and into the Arkansas River.   Lake County commisioners have declared a State of Emergency, fearing that heavy winter snowpack, and spring run-off will exacerbate the problem.

A large release of contaminiated water from the Leadville Mine Drainage Tunnel could wipe out parts of the town of Leadville, and contaminate the towns water supply with a lethal mix of heavy metals.  Communities like Buena Vista, Salida, Pueblo, Colorado Springs, and Aurora will likely be effected, as they look to the Arkansas River for their water supplies. 

Colorado's Governor, Bill Ritter, has asked President Bush to order the Bureau of Reclamation to take steps to reduce the building water pressure, and avert catastrophy. "Such a release, wrote Ritter, "could result in the loss of life, cause untold human misery, threaten the drinking water supplies for a half-million people, impact famers and ranchers and leave the river and the recreation economy it also supports degraded for decades."

State and federal agencies have agreed to a response that includes pumping water out of the mine drainage tunnel to relieve pressure, and to treat the water before it is returned to the river.  The Colorado Department of Public Health and Environment estimates the cost to launch an emergency water-pumping effort to range from $5 Million to $10 million dollars.