The heavy metals pollution moving into Washington in the Spokane River is definitely from Idaho’s Silver Valley, the U.S. Geological Survey said Monday.
Measurements taken in the river at Post Falls during this spring’s peak runoff show that Lake Coeur d’Alene is an “inefficient trap” for many of the metals traveling downstream from Kellogg and Cataldo, the agency said in a new report.
On May 22, some 8.5 tons of zinc, 1.65 tons of lead and one-third of a ton of copper were measured, according to the report.
The metals were both dissolved in the river water and trapped in sediment moved downstream by unusually heavy flows. This year’s runoff, with its high concentrations of metals, is “unusual” but likely to reoccur every 10 years, the agency said.
While they don’t violate drinking water standards, the contaminants “substantially exceed” what’s considered safe for aquatic life - and are dramatically higher than heavy metals in rivers not polluted by mining, said Paul Woods of the Geological Survey.
The agency did a computer analysis of rivers without mining activities to get a “background” heavy metals figure, said Woods, a water quality expert in Boise.
The Spokane River last May had 30 times more zinc, 26 times more lead and 1.6 times more copper than an unpolluted river, he said.
The agency’s test results are in accord with new river data released last week by the Washington Department of Ecology.
The tests don’t show the river’s overall water quality is bad and don’t prove that the pollution is coming from mines in the Silver Valley, said Laura Skaer of the Northwest Mining Association.
“I think it’s still speculation as to how much of these metals are contributed by mining and by the Superfund site, and how much is natural runoff,” she said.
The mining group supports a comprehensive river study, Skaer said.
“We don’t oppose that. But I’d like to see what the results are in the summertime, in the fall, and when we have non-flood events. They are still comparing a short-term event with long-term exposure, and I think there’s a leap of logic there,” she said.
Woods is convinced the Bunker Hill Superfund site is causing the pollution.
The site is a 21-square-mile area polluted by the now-defunct Bunker Hill lead smelter.
It’s undisputed that recent floods have carried tons of lead into Lake Coeur d’Alene: 68 tons in one day in February 1995; 500 tons during record floods in February 1996.
But until recently, when both the USGS and the Washington Department of Ecology began more comprehensive efforts to test the Spokane River, the extent of downstream pollution wasn’t well tracked.
Between 1991 and 1992, Lake Coeur d’Alene trapped 42 percent of the lead and 32 percent of the zinc carried into it, primarily from the Coeur d’Alene River, the Geological Survey said.
The agency’s Spokane River measurements are the first in a 10-year federal study of rivers in the Northern Rockies under the National Water Quality Assessment Program, one of 59 river systems under study nationwide.
In 1996, when heavy floods washed 500 tons of lead into Lake Coeur d’Alene, USGS didn’t have the money to take Spokane River measurements, Woods said.
That year, the river was running at 50,000 cubic feet per second. This year, it was running at 39,000 cfs on May 22, Woods said.
“This May was expected to be very high, but it only represented a 10-year flood,” Woods said.
The agency says most of the zinc washed downstream is coming from within the Silver Valley Superfund site at Kellogg, where cleanup is under way.
But the lead isn’t. It’s coming from farther downstream near Cataldo, Woods said.
“We are trying to get a handle on how much remediation there should be upstream from Lake Coeur d’Alene for the Spokane River to meet water quality criteria. We are getting closer to quantifying that,” he said.
Earlier this year, Gov. Gary Locke approved spending $300,000 to study pollution in the Spokane River. The study, coordinated by the state attorney general’s office, may be a first step toward a Washington state lawsuit against the Idaho mining companies that polluted the Coeur d’Alene Basin.
It also could lead to a negotiated agreement to clean up the entire river basin in Idaho and Washington.