The nation's highest court Monday devoted an hour to the question of whether water-borne mine tailings can be considered fill, or waste, or classified as both by federal agencies for regulatory purposes.

Opponents of the Kensington gold mine tailings plan contend mine tailings are actually a toxic slurry of water, chemicals, and solid waste.

A handful of environmental groups contend Coeur Alaska Inc. v. Southeast Alaska Conservation Council et al and State of Alaska v. SACC represents a dangerous assault on America's rivers, lakes and stream and the federal Clean Water Act, and threatens to set a precedent of allowing our lakes and streams to be used as mine tailings dumps.

Earthjustice attorney Tom Baldo contends the Kensington mine tailings plan is a test case that could reverse decades of settled law and return us to the day where mines could dump their tailings in clean lakes, rivers and streams.

However, U.S. Solicitor General Gregory Garre told the U.S. Supreme Court justices Monday, The expert agencies charged by Congress with implementing the Clean Water Act have concluded the discharge of fill material, like the mine tailings at issue in this case, should be permitted by the Army Corps of Engineers under section 404 of the Act, and are not subject to effluent guidelines applicable to permits issued by the EPA under section 402 of the Act.

‘This interpretation is grounded on more than three decades of agency pronouncements and reflects the collective judgment and expertise of the Army Corps of Engineers and the EPA in administering the Act, he asserted.

Chief Justice John Roberts wondered how a mining pipe could emit sludge, fill and effluent all at the same time. Justice Anton Scalia correctly assumed that fill material trumps effluent when agencies designate slurry as fill material.

Justice David Souter  expressed his dismay that if it's proper for Coeur d'Alene mines to do what they're doing here [using Lower Slate lake for tailings disposal], then the lake in the middle of the Everglades is an impoundment area, or a Great Salt Lake is an impoundment area.

Garre responded that at the end of this project, when the lake is going to be reclaimed, the agencies determined that it's going to be environmentally as sound, if not superior, for the habitats in Alaska, fish and wildlife. However, Souter replied, My problem is that you're treating-the Corps is treating as an impoundment area a whole natural lake as distinct from a settling basin.

The justice complained that during the period in which the deposits are going to be made, the natural life of this water body is going to be destroyed.

You are simply, or the Corps is simply, defining what would otherwise be a pollutant, suspended solids discharged into the water, by calling it fill material, he observed.

However, Garre contended that the primary environmental alternative for Kensington's tailings disposal was a dry tailings alternative that would have been problematic. One, it would have required the destruction of some 100 acres of wetlands; and two, it would have resulted in enormous stacks of tailings, 100 to 200 fett high, thousands of feet wide, that would actually dwarf the Pentagon and be visible from nearby Berners Bay.

The section 404 process is a rigorous environmental process, he argued, the EPA does have veto authority. We haven't seen these problems at all in the six years that the fill definition has been in place and I think it's simply untenable to suggest that these standards, which in section 4 require water quality determinations, wildlife, aquatic determination, would result in the sort of environmental harm that respondents have hypothesized...

Mining attorney Theodore B. Olsen noted that Kensington's permits followed 900 studies, the expenditure of $26 million, an evaluation by the EPA, the Corps of Engineers, the Department of Conservation of Alaska ...

However, Earthjustice's Waldo told the high court this is not some benign wet-sand kind of discharge. It's toxic slurry with a high pH level and with effects that are going to last for decades.

The case has now been submitted for a ruling by the Supreme Court.