Vision 2003 | Research and Scholarship at The University of Montana-Missoula

Western Montana’s largest river springs from the Continental Divide near Butte and gushes 320 miles northwest to Lake Pend Oreille in Idaho, knifing through spectacular mountain scenery along the way. Salish Indians fished all along the river, which the Corps of Discovery dubbed the Clark Fork, and pioneers found one of its headwaters so glittery and appealing they named it Silver Bow Creek.

But the ebb of history changed the Clark Fork Basin, and the pristine river system known to Indian ancestors is long gone, perhaps never to return. Western settlement brought mining, irrigation, rechannelization, town waste, farm runoff and four dams. As recently as the 1960s the Clark Fork ran red with mine waste, and today the river supports one-
tenth the trout it should. Silver Bow Creek now flows through a moonscape of mine tailings.

The river started its transformation in the 1860s when gold and silver mining and smelting started near its headwaters. Hard-rock mining of these ores climaxed in the raucous mining community of Butte in 1887, when 450 metric tons per day were processed at nearby mills. After 1892, copper production rose to the forefront inside Butte’s "Richest Hill on Earth."

Butte was honeycombed by 10,000 miles of underground mines that produced one-sixth of the world’s copper supply until the middle of the 20th century. Fortunes were made, and businessmen such as William Clark, Marcus Daly and F.A. Heinze became Wall Street powers. Mining kept food on the table for thousands of Montana families, and Butte’s powerful Anaconda Copper Mining Co. dominated the state’s economic and political life for decades.

But this prosperity had a price. Old West Montana had no environmental laws, and by the 1880s great heaps of gray waste rock dominated Butte’s landscape, while cobalt blue clouds rose from smelters to shroud the city. Trees and vegetation withered, and pets and farm animals drinking from area puddles died. One 1880s writer describes arriving in the mining Mecca to find `stifling sulphur’ fumes so thick he couldn’t see across the street, and a policeman 'with a sponge over his mouth and nose to protect him from the fumes' guided him to his hotel.

Another account said arsenic in the smelter smoke could bleach skin, and mothers back East would send their daughters to Butte to help them attain that alabaster, porcelain complexion so sought after at the time.

The mine tailings — as well as flue dust and slag from the smelters — contain toxic levels of arsenic, cadmium, copper, lead and zinc. When the giant Anaconda smelter 20 miles west of Butte started work in 1902, contamination followed. One ranch 12 miles downwind lost 1,000 cattle, 800 sheep and 20 horses during the first year of smelting.

Much of the pollution from area smelters wound up in Silver Bow, Warm Springs, Willow and Mill creeks and from there flowed into the Clark Fork. Through the 1930s, ‘40s and ‘50s there were no fish in the river’s entire upper basin. Occasional storms or other high-runoff events would stir up sediment and send reddish, toxic pulses of heavy metals downstream, killing aquatic life for many meandering miles.

The pollution also created `slickens’ downstream from Butte and Anaconda. Not much grows in these riverside dead zones but crusted deposits ranging in color from gray to blue or bright green. Most slickens were formed by sediment deposited by large floods in 1908 and 1910. Some areas contain so much copper that the bones of cattle that died there are stained a vivid green.

Eventually realizing the environmental damage being done, the Anaconda Co. built the 2,400-acre Warm Springs Ponds in the Deer Lodge Valley between 1911 and 1959 in an attempt to trap the tailings before they entered the Clark Fork. (Work on the ponds continues to this day.) The ponds did stop most heavy metals from reaching the river — except during heavy runoff events — but they failed to completely stop passage of arsenic. The four Clark Fork dams also seem to contain downstream contamination somewhat, but UM researchers suspect some pollutants may travel 300 miles or more — all the way to Lake Pend Oreille.

By the early 1910s the Anaconda smelter was processing 11,500 metric tons of ore per day, and by the time depressed prices shut the smelter down in 1980, more than 1 billion metric tons of waste rock had been produced in the Butte area.

Underground mining in Butte sputtered in 1976, but by then the Anaconda company was turning the Richest Hill on Earth into the 900-foot-deep Berkeley Pit, which gobbled up part of the town as it gaped wider. The pit grew from 1955 until 1983, when pumps that kept groundwater from flooding it were shut off. Since then the pit has slowly filled with water so acidic that 342 snow geese died after landing there in 1995.

The Anaconda company sold its holdings to Atlantic Richfield Co., the oil giant, in 1978. After that with the diggings unprofitable, ARCO, now part of BP, closed its Montana mines and now faces nearly $1 billion in inherited cleanup costs. One ARCO plan is to build a treatment plant for the Berkeley Pit water so it never reaches drinking aquifers. The acidic water will have to be treated forever.

The heyday of Butte-area mining has now passed, with one active mine scheduled to reopen this fall. The mining is largely gone but its legacy remains. Mining areas typically have elevated disease death rates, and a 1979 study found the death rate in Butte from disease was among the highest in the nation between 1949 and 1971.

Western Montana’s biggest river also is now part of the nation’s largest Superfund cleanup site. Much work already has been done on the river, significantly improving its water quality, but much work remains to be done. The two largest contaminated areas within the site are the Milltown Reservoir near Missoula and a 120-mile stretch of river, which starts at Warm Springs Ponds and extends downstream.

The Environmental Protection Agency, the state of Montana and industry partners are continuing work to restore more function in the river, including the proposed removal of Milltown Dam, which has millions of yards of contaminated sediment sequestered behind it. Public comment is now being taken about how the restoration should be done.

So, as it has for the past 140 years, the Clark Fork flows toward an uncertain future.

Cary Shimek, Managing Editor
Judy Fredenberg, Office of the Vice President for Research and Development
The University of Montana-Missoula
32 Campus Drive | Missoula, MT 59812
phone 406-243-2522 | fax 406-243-4520
Copyright 2007 The University of Montana

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