For years, the EPA has agreed with mining officials that toxic sediments stuck behind the Milltown Dam on the Clark Fork River near Missoula, Mont., were best left alone. But when polluted waters escaped from the dam in February, they killed fish and energized activists, who renewed their call for the agency to remove the mine wastes.
Following the fish kill,
tests by Missoula's Health Department found greatly elevated levels
of copper, zinc and arsenic in the once-dammed waters. Metals in
the Milltown Reservoir were accumulated during more than a century
of mining and smeltering upstream, in Butte and Anaconda
But EPA officials haven't changed
their position. They said removing the contaminated sediment is
still not worth the money, a conclusion shared by Atlantic
Richfield Co., which now owns the site. Instead, the agency wants
to dig monitoring wells to track the plume of pollution as it moves
past the dam. The wells would signal EPA when to tell people their
drinking water was becoming contaminated.