Teck also contends it is not the sole source of any pollution, as almost 1,000 metals mines and mills have operated in the Columbia River watershed above Grand Coulee since the late 1800s, contributing millions of tons of mineral-rich pollution to the river.
"These metals, as well as metals from landslides and erosion, dwarf Teck's discharges," the company contended.
Since 2006 Teck has been engaged in a major study, under the direction of EPA, of mining pollution in the river. The company has spent more than $55 million on this study. The company contends the study must run its course before any decisions about the pollution can be made.
Godlewski said preliminary findings are encouraging.
"The fish is safe to eat," he said. "The water is safe to play in."
Attempting to hold Teck responsible for the pollution interferes with the sovereign authority of Canada and British Columbia, Teck contends. Canada has repeatedly expressed disapproval over the case, including sending a diplomatic note of protest to the State Department.
The Colville tribes grew concerned about the pollution because their reservation is bordered on the west and south by Lake Roosevelt.
"Teck's actions injured our tribes' lands, waters and other natural resources," Sirois said. "The Columbia River and Lake Roosevelt is a center of our tribal culture."
The tribes and state contend in court documents that as Grand Coulee Dam transforms the free-flowing river into slack Lake Roosevelt, the slag and effluent from Trail sink into the sediments of the lake, rather than flow over the dam.
At least 8.7 million of the estimated 9.97 million tons of slag discharged from the Trail smelter over the decades flowed into Washington, and an unknown portion of its remains in the lake, the state and tribes contend.
"Teck Metals has already acknowledged that it released millions of tons of toxic pollution into Washington state, and we feel confident the federal court will find that U.S. cleanup laws apply to Teck," said Jim Pendowski of the state Department of Ecology.