Pollution in the Columbia River can be attributed to an industrial plant right across the U.S. border, an Interior Department agency said in a report on Monday that backs up claims by a Washington tribe seeking cleanup of the area.

In cooperation with the Confederated Colville Tribes, the U.S. Geological Survey examined sediment at six locations in Lake Roosevelt. The lake is downstream from the Teck Cominco plant in British Columbia, the largest lead and zinc smelter in the world.

According to the USGS, scientists discovered byproducts of the smelter in 100 percent of the samples. "Elevated concentrations of arsenic, cadmium, copper, lead, mercury, and zinc occurred throughout much of the accumulated sediments," the report stated.

The findings raise concern because every sample exceeded tribal guidelines for cadmium, lead, and zinc. Levels of arsenic, copper, and mercury were just below the guidelines.

"These and other results from our study indicate that the liquid effluent from the Teck Cominco smelter is the primary contributor of the large concentrations found in sediment samples from the middle and lower reaches of Lake Roosevelt," said USGS hydrologist Stephen Cox, lead author of the report.

The report is ammunition for tribal officials who say the smelter poses a health and environmental risk to the reservation. The tribe, which has treaty rights on the Columbia River, says that fish are contaminated by dangerous chemicals and that pollution is a deterrent to tourism and economic development.

In hopes of getting Teck Cominco to clean up the mess, tribal members filed a lawsuit under the Superfund law. The federal government and the states of Washington and Oregon are backing the claim in federal court.

But Teck Cominco is challenging whether it is subject to the jurisdiction of the United States since the smelter is located on Canadian soil. The company's motion to dismiss was rejected by a federal judge and the decision is now on appeal to the 9th Circuit Court of Appeals.

The tribe and the federal government counter that Teck Cominco can't escape responsibility for actions that impact the U.S. The study attributed the pollution to "decades" of the smelter's operation and reported that trace elements of the chemicals were found all the way from the Canadian border to the southern end of the Colville Reservation next to the Spokane Reservation, a distance of more than 100 miles.

If found liable under the Superfund law, Teck-Cominco could be forced to pay for cleanup of the area. The cost of the effort is not known.

In response to a separate lawsuit filed by the Environmental Protection Agency under the law, the company offered to pay $13 million to assess health and environmental concerns. The EPA rejected the offer and is seeking to force Teck Cominco to comply with a cleanup order.

Teck Cominco says it has spent more than $1 billion to upgrade operations of the smelter, which opened in the 1890s. The company has been in talks with the State Department and U.S. diplomats, some of whom are concerned that the EPA's actions could impact business relations with Canada.

The smelter isn't the only Teck Cominco operation under scrutiny. In partnership with an Alaska Native corporation, he company operates the largest zinc mine in the world near two Alaska Native villages. Residents of Noatak and Kivalina are worried that the mine is polluting their food supply.

USGS Report:
Vertical Distribution of Trace-Element Concentrations and Occurrence of Metallurgical Slag Particles in Accumulated Bed Sediments of Lake Roosevelt, Washington, September 2002 (March 2005)

Relevant Links:
Colville Confederated Tribes - http://www.colvilletribes.com
Teck Cominco - http://www.teckcominco.com