One of Montana’s founding industries was mining. The history of the huge mines at Butte—to say nothing of the 1860s Gold Rush, the sapphire mines, the silver and lead mines, and on and on—have all contributed mightily to the spunk and character of the state. However, recent years have revealed just what enormous environmental damage is now being exacted by the state’s mining past.

Even though copper mining has ceased in Butte, the Berkeley Pit remains a mile-deep reservoir of toxic water. In the 1980s, investigations revealed that many homes in the Butte area, built on foundations made from mining tailings, were highly radioactive. The Butte-Anaconda area is the nation’s single largest Superfund site. (The Environmental Protection Agency’s Superfund allows for cleanup of particularly toxic areas.)

Downstream from Butte, in the drainage of the Clark Fork River, recent restoration programs have been largely successful in reintroducing trout to this magnificent river. By the 1950s the river’s chemical load was so high that it had become essentially sterile. However, the arsenic and heavy metals that flowed in the river for nearly a century haven’t disappeared; many of these deposits are merely coated in mud.

Most of these toxic sediments lie behind the Mill Town Dam, just upriver from Missoula, which corrals the waters of the Clark Fork and Blackfoot Rivers at their confluence. The dam, an increasingly unstable log structure that was built in 1907 to generate electricity for an adjacent lumber mill, now serves primarily as a repository for sediment and mining wastes.

After years of debate about how to address the issues presented by the Mill Town Dam, NorthWestern Energy, the dam’s owner, and Arco, which is liable for the contamination, agreed to an EPA recommendation to remove the structure and restore the rivers by extracting the toxic sediments from the river bottom—all without harming downstream fish populations.

The scope of the project was enormous: The price tag for removing the dam and the sediment was $120 million and involved removing the 500-foot-wide wooden dam and 2.6 million cubic yards of sediment. In 2008 the last of the dam and sediments were removed, and the rivers were rejoined as free-flowing streams of water.

However, by far the greatest human tragedy related to past Montana mining involves the small Northwest Montana community of Libby, site of a vermiculite (used in planting soil and kitty litter) mine. Libby residents discovered in the late 1990s that mixed in with the vermiculite, which many residents had spent their lives mining and that stood in piles around the town, was a mineral called tremolite, a rare and toxic form of asbestos. Tragically, the miners and many townspeople are now suffering from the effects of asbestos poisoning. Many have died from asbestos-related cancers, and even more are ill. Although the W. R. Grace Company (which owned the mine) and the government knew about the asbestos, nothing was done to stop the dust that contaminated the town. In 2000, after the Seattle Post-Intelligencer and other news sources began running stories on the asbestosis, W. R. Grace bought back the mine (which they’d sold years before), banned EPA officials from it, and backed off from promises to clean it up. In 2001 the W. R. Grace Company filed for bankruptcy, claiming it could not handle the deluge of personal-injury lawsuits. By the summer of 2001 about 5,500 Libby residents had been tested for asbestos. Nearly 20 percent of those tested had lung abnormalities. Many homes are contaminated, thanks to the free vermiculite insulation that was available for years in big piles outside the processing site. The EPA is managing an emergency cleanup of the town and has found contamination in places such as the high school athletic field.

As Montana enters the 21st century, its mining past is an increasingly heavy burden.