Berkeley Pit

Berkeley Pit Viewing Stand

Useful Information

Location: Butte.
exit 126, north to Park Street and then east. Well marked and has plenty of parking.
(46°0'58.26"N, 112°30'42.54"W)
Open: MAR to NOV daily. [2006]
Fee: Adults USD 2. [2006]
Classification: MineCopper Mine
Light: n/a.
Dimension: Pit: L=2130 m, W=1,700 m, VR=490 m.
Lake: D=275 m, V=100,000,000,000 l.
Guided tours:
Address: Berkeley Pit, Continental Drive, Butte, MT 59701, Tel: +1-406-723-3177, Fax: +1-406-723-1215, Free: 800-735-6814.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


1955 opened and operated by the Anaconda Mining Company.
23-APR-1982 pump station of the Kelley Mine shut down, ground-water levels rise immediately.
1995 342 migratory snow geese landed on the water and died.
2004 observation deck deeded it to the Chamber of Commerce.


During its operation 1.5 billion tons of material were removed from Berkeley Pit. 290 million tons of copper ore made this the Richest Hill on Earth. To create the pit, the two communities Meaderville and McQueen, and much of Butte's East Side were destroyed.


Berkeley Pit is a former truck-operated open-pit copper mine. It was started in 1955 and closed in 1982. When it was abandoned it started to fill with ground water, which is common after operating mines are shut down and the pumps are turned off. The lake is today 275 m deep, has a surface of 2,700,000m² and contains 100 billion liters of water.

The water is drainage water from other closed mines around, containing decent amounts of arsenic, copper, cadmium, cobalt, iron and zinc. Even (weak) sulfuric acid is found in the harmless looking gray water. At first nobody thought about the dangers of the poisonous new lake. But in 1995, when 342 migratory snow geese died after they had landed on the water, the public was alarmed. Now the air is filled with the sound of noisemakers, which were installed to keep birds away.

However, the pit became one of the most difficult and expensive pollution problems of the State. It is the largest Superfund site, which means it is controlled by the U.S. Environmental Protection Agency (EPA) and the Montana Department of Environmental Quality (DEQ) under the United States environmental law that is officially known as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). They defined the maximum elevation that water levels will be allowed to reach. There is a new water treatment plant built, which will treat contaminated water from various drainages which now flows into the Pit. And probably the water will even be used for mining in the future. It has already been used to win metals and minerals, but the rentability depends on the price of the products and the price of the needed energy. At the moment the processing of the water is not rentable.

The Berkeley Pit itself may not be visited, but pit owner Montana Resources has built an observation deck some years ago. It has been free until 2004, but they deeded it to the Chamber of Commerce together with one hectare of ground. Now the site is developed, with new toilets, cafe, and a souvenir shop selling copper goods. And it is not free any more.