The River They Cleaned

As recently as the nineteen sixties and nineteen seventies, the Clark Fork River ran red through Missoula. The color came from copper-mine waste discharged into the river's headwaters in Butte, more than a hundred miles to the east. By the time the contaminated water reached Missoula, it had picked up enough additional material to stain the river a color that no river should be.

The deeper problem was underground. In nineteen oh eight, a dam was built at Milltown, seven miles east of Missoula, where the Blackfoot River joins the Clark Fork. Within months of its completion, a massive flood washed millions of tons of mine-waste sediment downriver and deposited it behind the dam. For most of the twentieth century, that sediment, laden with arsenic, copper, zinc, and lead, sat on the river bottom and leached into the groundwater. Arsenic contamination was detected in the drinking water of Milltown residents in the early nineteen eighties, and the site was added to the Superfund National Priorities List in nineteen eighty-three.

The cleanup took more than two decades of study, legal negotiation, and planning. In two thousand six, workers began removing the dam and the two-million-plus cubic yards of contaminated sediment behind it. The dam was gone by two thousand eight. The Milltown State Park that replaced it opened on the restored riverbanks not long after.

The Clark Fork through Missoula today supports fly fishing, kayaking, and swimming where there was once industrial waste. The recovery is incomplete in places and ongoing in others. But the river that runs through Caras Park and under the Higgins Avenue Bridge is not the river the Clark Fork had become. The cleanup, long and expensive and contested, is one of the largest success stories in American environmental remediation.