Atlanta Gold, in an official statement sent out June 16, said polluted sediment from its mining project sent arsenic and iron into Montezuma Creek, which pushes its water into the Middle Fork of the Boise River.
Atlanta Gold blamed high spring runoffs leading to a ground collapse in one of its mines, pushing the sediment over its bulkhead and into the creek. The arsenic and iron discharges exceeded standards set by the U.S. Environmental Protection Agency.
According to a company statement, the polluted water peaked at more than 1,000 gallons per minute on May 17 and again on June 10, forcing Atlanta Gold to take portions of its treatment plant off-line for maintenance.
It was more than seven years ago when Boise Mayor Dave Bieter stood alongside the Boise River and said, "I have concluded that the Atlanta Gold project is simply a terrible idea."