The U.S. Supreme Court sided with Coeur Alaska and the state of Alaska on Monday, meaning tailings mine waste from the Kensington gold mine can be dumped into Lower Slate Lake. It's the first time in 30 years a U.S. mine will be allowed to transform a natural lake into a tailings pond.

The court's ruling, one of the last of its term, resolves a lawsuit that the Southeast Alaska Conservation Council, Lynn Canal Conservation and the Juneau Group of the Sierra Club brought in 2006. Both sides say it sets a precedent -- one hailed by the mine industry and builders but deplored by environmentalists. It greenlights the Kensington mine that has been in the works for two decades but on hold since mid-2007. It's expected to support 200 well-paid workers once operational.

Juneau District Ranger Pete Griffin of the U.S. Forest Service, the lead agency on federal permits for Kensington, said he was unsure about just when Kensington would get its permits back.

The Supreme Court sent the case back to the district court to reinstate the mine's permits.

"Obviously, we're very pleased with the decision," said Tony Ebersole, spokesman for parent company Coeur d'Alene Mines Corp.