Filed Under The Environment

The Berkeley Mine Pit: Butte’s Scenic Toxic Lake

The Berkeley Mine Pit is the most expensive site on the EPA’s superfund list, filled with water so acidic it can dissolve the propeller of a boat.

Butte, Montana’s history is inseparably tied to mining. A gift shop on the outskirts of town sits next to a massive man-made pit filled with 40 billion gallons of water. Some visitors comment on the beauty of the contrast between the “blue sky and emerald green waters” and enjoy signs that give brief snippets about the history of the Anaconda Copper Mining Company and the pit. Others who visit know that that the pit is filled with water so acidic that it can dissolve the propeller of a boat. In 2016 the poisonous water was responsible for the death of an estimated 4,000 geese who stopped for a drink. The Berkeley Mine Pit is now the most expensive site on the EPA’s superfund list.

Underground mining operations date back to the 1870s in Butte. By 1955, however, Anaconda decided that it would be more profitable and safer for miners to dig straight down to copper veins instead of tunneling to them. This method resulted in a growing pit. The people of Butte proudly identified as miners, but the pit exposed the community to a type of mining never before experienced and they began complaining to company officials about the noise and dust from nearby explosions. As the pit grew deeper and wider and more waste was produced, Anaconda saw only one way to stop complaints and keep their operation going: obtain more land.

Anaconda faced the task of dismantling communities that they helped create. East Butte, Meaderville, McQueen, Dublin Gulch, and Finn Town were towns of immigrant miners close enough to the Berkeley Pit that the company deemed their destruction necessary to continue mining operations. Fortunately for Anaconda, they already owned most of the land in these towns, they needed only to buy or trade the houses on top of it. A sign by the pit today reads, “many of the relocated residents didn’t mind because it meant that good paying jobs would stay in the community.” While it is true that these communities were eventually abandoned and engulfed by waste or the pit itself, the reality of people leaving their homes, churches, and baseball fields to be destroyed was more complicated. One resident remarked, “People said they’d fight, but then they jumped.”

Anaconda was no longer the typical pre-WWII mining company that hired detectives to intimidate or beat workers into submission. They used legal means to move workers and their families to different parts of town. They offered fair sums of money for houses or offered a trade so people could immediately move into a house in a different town also owned by Anaconda. Though many took the deals offered by the company, there were always holdouts. In 1961 however, a bill passed in the state legislature that gave private companies like Anaconda the right to exercise eminent domain to expand pit operations. Though the process was used sparingly, Anaconda could take property if they wanted to, making resistance to pit expansion futile. Still, one man in charge of covering the old school in Meaderville with mine waste said, “I felt like a murderer. Progress does have its price.”

By the 1980s, pressures from environmentalists and the financial state of Anaconda Copper led to the closure of the Berkeley Pit. Pumps that kept surrounding groundwater from the pit were turned off, and the pit has been filling with toxic water ever since. In 1983 the pit was placed on the EPA’s superfund list. Last year, ground was broken on a facility that will stop water in the pit from raising to levels that would poison surrounding water supplies in Butte. The pit stands today as a poignant reminder of the large-scale destructive effects of capitalism in the West and represents the complex relationship between people and the resources on which they depend for jobs, and ultimately, life. The Berkeley Pit cannot be discussed in Butte without a reverence for the thousands of miners that sacrificed limbs, time, and sometimes their lives all to earn a decent wage. As we look forward to solutions for Berkeley, we must not forget to remember how and why it was created.


Berkeley Pit
Berkeley Pit The pit continued to expand until its closure in 1982. Source: Lowe, Jet. Historic American Engineering Record, Library of Congress,
Berkeley Pit
Berkeley Pit The pit was long a source of pride for the town, and pictures like this were even used on postcards. Source: Peck, Clinton. Butte-Silver Bow Public Archives, Clinton Peck Collection Object ID: 2011.085.004. 
Berkeley Pit, McQueen Neighborhood
Berkeley Pit, McQueen Neighborhood This picture shows the proximity of the Berkeley pit to neighborhoods like McQueen. The pit eventually consumed them. Source: Peck, Clinton. Butte-Silver Bow Public Archives, Clinton Peck Collection, Object ID: 2011.085.020.
Berkeley Pit
Berkeley Pit Today the pit is filled with toxic water that threatens to contaminate surrounding groundwater. Source: Peck, Clinton. Butte-Silver Bow Public Archives, Clinton Peck Collection Object ID: 2011.085.004. 



Sam Heywood, Brigham Young University, “The Berkeley Mine Pit: Butte’s Scenic Toxic Lake,” Intermountain Histories, accessed July 20, 2024,