Drainage from a mining site can have water-quality problems.

Detailed Description
Water running through mine tailings can become polluted
A U.S. Geological Survey (USGS) scientist and a volunteer sample metal-rich water from a seep draining a pile of mine tailings along Silver Creek, near Park City, Utah. Seeps such as this one can come from tailings piles that are remnants of past mining activities. Contaminants from hardrock mining can come from adits, waste rock piles, and from tailings that were stored along streams.
Sources/Usage
Public Domain.