Avalanche of water threatens Colorado town

More than 1 billion gallons of contaminated water — enough to fill 1,500 Olympic-sized swimming pools — is trapped in a tunnel in the mountains above the historic town of Leadville and threatening to blow.

The water is backed up in abandoned mine shafts and a 2.1-mile drainage tunnel that is partially collapsed, creating the pooling of water contaminated with heavy metals.

County officials have been nervously monitoring the rising water pressure inside the mine shafts for about two years. An explosion could inundate Leadville and contaminate the Arkansas River.

Lake County Commissioners have declared a local state of emergency....