Teck admitted last month to dumping millions of tonnes of toxic waste from its smelter in Trail into the Columbia River for more than 100 years.
But Teck is still fighting a legal challenge by Washington state and one its largest Indian reservations, arguing the U.S. has no jurisdiction over a Canadian mining company.
"Teck has, from the very start, believed the way to resolve these are voluntary cooperative approaches where the two countries work together to resolve the issues," said Dave Godlewski, Teck's vice president of environmental affairs.
The state and a native group, the Colville Confederated Tribes, claim the pollution affected the natives' health and ecology.
Their lawyer, Paul Dayton, said Teck's last hope is the question of legal jurisdiction.
"The argument will be Teck intentionally discharged its waste and knew it would flow down the Columbia and be found in Lake Roosevelt," Dayton said.
"And whatever harm that resulted would be in the state of Washington and therefore the test for jurisdiction is met."
If the court rules against Teck. another phase of the case will begin to determine how much the company has to pay for pollution in a different country.