Denver (AP) Another partial tunnel collapse is complicating efforts to remove the threat of flooding in the hills above Leadville, where more than one billion gallons of toxic water has pooled.

Lake County Commissioner Mike Hickman wants the state to drain the Canterbury Tunnel, which is believed to be emptying into a second tunnel where the water has collected.

Hickman sent a letter to Governor Ritter Tuesday asking that the state spend $3.5 million to drill a well and pump water out of the Canterbury tunnel, which once provided drinking water to Leadville.

A partial collapse in that tunnel has sent its clean water into the Leadville mine drainage tunnel. State officials say they're studying the problem.