The proposal to increase oil development in the National Petroleum Reserve-Alaska on the western North Slope imperils the "largest, most productive freshwater lake" in Alaska's Arctic, the area's wildlife and the native people who depend on the natural resources, he said.

"We are at the 11th hour, but it's not too late for public opinion to be heard to prevent this from happening," he said from Washington in a telephone news conference.

The BLM plan, announced earlier this month, seeks to allow leasing on 387,000 acres in and around Teshekpuk Lake, a vast water body near the Arctic coastline. The lake and the area around it had been excluded from leasing under the 1998 plan issued by the Clinton administration.

The 45-day public comment period on the plan expires Aug. 2.

Oil companies and their supporters want access to the area because of the rich geological structure underlying it. All the commercial North Slope oil discoveries have been within 25 miles of the coast, in the Barrow Arch formation that cuts through the Teshekpuk Lake area.

But the Teshekpuk Lake area is also valuable to wildlife, Alaska environmentalists say.

It serves as the calving ground for a huge caribou herd and as a nesting and breeding site for migrating waterfowl, said John Schoen, senior scientist for Audubon Alaska. It is one of the most important goose molting habitats in the entire Arctic, he said.

The NPRA was set aside for its energy-producing potential in 1923. But for decades the area was only sporadically explored. The oil industry concentrated instead on Prudhoe Bay and surrounding oil fields well to the east.

New interest in the petroleum reserve was kindled in the mid-1990s, when Arco Alaska Inc. discovered the 430 million barrel Alpine field on state land at the eastern border.

Two lease sales held in 1999 and 2002 for areas in the northeastern part of the reserve drew nearly $170 million in combined high bids. A June 2 lease sale that offered 5.8 million acres in the northwestern section of the reserve drew $53.9 million in high bids.