Butte's Berkeley Pit Experiences Water Level Rise After Seven-Month Pump Stoppage
The Berkeley Pit, a 1,780-foot-deep former copper mine in Butte, Montana, experienced a significant rise in its acidic lake water level after its pumps were out of operation for seven months. The pumps were removed in January due to movement in the slope beneath the only access road to the pump station. They were not restarted until August 31, during which time the lake's water level rose by approximately 3 feet. This rise brought the water in a nearby flooded mine, the Pilot Butte Mine, to less than 26 feet below the regulatory limit of 5,410 feet above sea level, a level that, if crossed, could lead to contaminated water flowing into Silver Bow Creek.