Mining and contamination of western waters

According to the Environmental Protection Agency, mining in the western United States has contaminated stream reaches in the headwaters of more than 40 percent of the watersheds in the West. 

EPA is spending $30,000 per day to treat contaminated mine drainage at the Summitville Mine in Colorado, which will cost an estimated $170 million to clean up. 

Remediation of the half-million abandoned mines in 32 states may cost up to $35 billion or more.

See EPA:  Liquid Assets