A U.S. federal district court judge ruled that Teck, a Canadian mining company, is liable for the costs of cleaning up contamination in the Columbia River south of the border from decades of dumping slag and effluent from the company’s Trail operations in Canada.

In his decision, Judge Lonny Suko ruled that, “for decades Teck’s leadership knew its slag and effluent flowed from Trail downstream and are now found in Lake Roosevelt, but nonetheless Teck continued discharging wastes into the Columbia River.”

Judge Suko noted that the company admitted treating the international waterway as a free waste disposal service. Specifically, the judge found that from 1930 to 1995, Teck intentionally discharged at least 9.04 Mt (9.97 million st) of slag that included heavy metals such as lead, mercury, zinc and arsenic.

The judge also found that Teck knew the hazardous waste disposed of in the Columbia River was likely to cause harm.

The decision gives the U.S. Environmental Protection Agency (EPA) the ability to force Teck to pay for the cleanup, and potentially for any ongoing damages and losses that result from the ongoing contamination. That issue has yet to be determined by the court, The Globe and Mail reported.

Some believe the landmark case could have implications for mining and other industrial interests on both sides of the border. The Canadian government, the province of British Columbia and the U.S. National Mining Association have all intervened in the case to argue that the issue should be resolved bilaterally.

As they awaited the judge’s decision, Washington state officials were optimistic.

Eight years after the case was launched and on the eve of a trial this fall, Teck admitted to discharging slag and liquid effluent into the river from 1896 to 1995. But it argued the U.S. law that forces companies to clean up contamination sites, known as the Superfund law, was never intended to reach across the international border.

But Kristie Elliott, lawyer for the Washington state Attorney-General, said complaints about the contamination from the Trail smelter surfaced as early as the 1940s, when farmers from Washington state sued Cominco, Teck’s predecessor, over air pollution from the smelter. That case was eventually resolved in arbitration by the two federal governments, and set a precedent for cross-boundary pollution law.

The company took out insurance to cover liability, but didn’t stop discharging effluent for decades, she said.

Teck has spent about a billion and a half dollars has modernizing Teck’s Trail Operations over the past 25 years. A new furnace installed in 1996 cut emissions dramatically.

Last month, Teck completed a $5.8-million project to reduce the risk of a spill into the river.

The company is now installing a $1.2-million automated leak detection system, and a $125-million acid plant that will reduce sulphur dioxide emissions a further 15 to 20 percent.

Recycled lead makes up about 20 per cent of total production and anything that can be used or recycled is, right down to granules of slag sold for processing into Portland cement.