Cold, rapid and icy blue, the Clark Fork is Montana's largest river. It begins its journey as Blacktail Creek, tumbling down from the Continental Divide at Pipestone Pass, near Butte, and threads its way between the Flint Creek, Sapphire and Garnet ranges on its way to Missoula. A century ago, one of North America's largest copper booms rattled the river's headwaters in Butte. Several hundred mines burrowed beneath the city, and in 1908, a flood washed tons of contaminated sediments from those mines into the river. Arsenic, copper, zinc, lead and cadmium contaminated millions of tons of sediment along 120 miles of the river's banks—all the way to Missoula. The river's legendary but struggling trout all but vanished.
Then, in the 1980s, researchers discovered arsenic in the groundwater of Milltown, a city built along the river about 100 miles west of Butte. This discovery sparked decades of litigation and, ultimately, the nation's largest watershed restoration project—the $1 billion-plus Upper Clark Fork River Superfund Complex, which is still in progress today.
That's what drew chemist Heiko Langner to the University of Montana in 2002. The German native had moved to Bozeman several years earlier, as much for its backcountry skiing as for graduate school at Montana State University. He remained to study the Clark Fork. His field was environmental chemistry, and he was intrigued by the effects of contaminants, such as those from Butte's mines, on natural environments.
In 2006, Langner, who was also a recreational birder, teamed up with biologists to examine how those contaminants might affect birds that prey on fish. They studied ospreys along the banks of the Clark Fork, taking blood samples from chicks to determine whether contaminated fish were hurting them. In 2007, Langner's blood samples showed the cleanup effort appeared to be working, at least in regard to arsenic, copper, zinc, lead and cadmium.
"Those contaminants everyone was talking about—it turns out that none of those seemed to be affecting the ospreys directly," he said last year. "What we were finding instead was real high concentrations of mercury," a neurotoxin that can accumulate in the tissues of fish and other aquatic organisms. At sufficient concentrations, it harms the predators—the ospreys, otters and even human beings—that eat them.
Langner wasn't surprised by the presence of mercury, which was often used historically in metal mining. Rather, he was surprised by the "odd geographic distribution," he said. The highest mercury levels were found in chicks nesting farther downstream from Butte's copper mines, and vice-versa. "We actually double-checked if we had switched some samples or if we made some other mistake," he said. But the following year, the researchers confirmed the neurotoxin wasn't coming from Butte. Over the next five years, Langner's team traced most of the mercury to a single source: the remains of the Rumsey Mill, an abandoned silver ore-processing facility on a small tributary called Fred Burr Creek.
Meanwhile, hundreds of state and federal employees, students, advocates, volunteers and contractors have spent over a decade planning, litigating and working on the Upper Clark Fork's Superfund cleanup. They've excavated a third of the soil from the riverbanks and shipped it to repositories upstream near Opportunity, a town of 500. They've torn down a dam, rerouted the river, restored wetlands and planted riparian vegetation. There has been a lot of successful restoration, but it has a long way to go.
Extending that work to curb the mercury contamination would be a fairly easy fix if Langner's research is correct and it's mostly all coming from one source. It would cost a fraction of what's already being spent on the massive cleanup on the very same river system. But here's the catch: The Superfund project, which is projected to take another several years, legally can't do anything to address the contaminants from Rumsey or from the hundreds of other abandoned mines upstream. And both federal and state agencies lack the necessary funding to deal with them.
So Langner and others are asking themselves: How can so much energy be put into a cleanup when some of the most dangerous contaminants are being ignored? The answer, as with so many natural resource issues in the West, lies in how the money flows.
The Environmental Protection Agency's Superfund program has a relatively small pot of money (primarily from a now-discontinued tax on industry) to reclaim hazardous sites, such as old mines. That's not enough to pay for much reclamation work, so it's used for litigation, to force responsible parties to pay for the damage they did. In the Upper Clark Fork Superfund Complex, the Superfund law allowed the EPA and the state of Montana to sue the Atlantic Richfield Company, or ARCO, a multinational mining conglomerate. ARCO bought Anaconda Copper Mining Company, which owned many of Butte's hundreds of mines (including the famous Berkeley Pit), in the '70s and operated for several years before closing them. Now, the company is paying to clean them up. Legally, that money can only be used to remediate damages from the ARCO-owned mines in the Clark Fork area. But ARCO never owned Rumsey or any of the other hundreds of abandoned mines in this watershed. At this point, no one owns them. And without anyone to sue, the EPA is close to helpless.
What's more, the Superfund work could even exacerbate the problem.
"There is a different and complicated (chemistry) with mercury," Langner said. "(Cleanup) measures that can be great for copper or zinc can be counterproductive with regard to mercury."
As part of the Clark Fork's restoration work, crews have sculpted a new channel and restored wetlands alongside it. Wetlands by nature are full of bacteria and low in oxygen, and when mercury encounters these conditions, it can easily become methylmercury, a much more toxic form of the chemical.
The mercury from abandoned mills and mines is also a problem for anglers. "It's not compatible with blue-ribbon trout fishing," Langner said. The area's legendary trout fishing draws tourists—and money—from around the world, but it depends on clean waters.