By Maria L. La Ganga, Los Angeles Times

SEATTLE — The U.S. Environmental Protection Agency took the first step Friday toward possibly halting construction of the largest open-pit mine in North America, declaring that Alaska’s Bristol Bay — home to the most productive sockeye salmon fishery on Earth — must be protected from what could be irreversible damage.

“Extensive scientific study has given us ample reason to believe that the Pebble Mine would likely have significant and irreversible negative impacts on the Bristol Bay watershed and its abundant salmon fisheries,” EPA Administrator Gina McCarthy told reporters Friday in announcing the agency’s decision.

“It’s why EPA is taking this first step forward in our effort to ensure protection for the world’s most productive salmon fishery from the risks it faces from what could be one of the largest open-pit mines on earth,” she said. “This process is not something the agency does very often, but Bristol Bay is an extraordinary and unique resource.”

Conservation groups hailed the decision to use provisions of the Clean Water Act to potentially stop Pebble Mine as a victory for the critical ecosystem, for Alaska Natives who depend on the salmon fishery for their survival, and for the commercial fishing industry.

Chris Wood, president of Trout Unlimited, said in a written statement that “it is difficult to overstate the significance” of the EPA announcement. “If the EPA follows the science and follows through on this, it will rank as one of the most significant conservation achievements of the past 50 years.”

Tom Collier, chief executive of the Pebble Limited Partnership, vowed that his company would fight the EPA and prevail.

“I think we’ll drive a stake through this notion that there ought to either be a veto or restrictions placed on this project before we even file our application for a permit,” Collier said. “We don’t think they have the authority to do a veto before a permit has been filed.”

Pebble Mine is a potential source of gold, copper and molybdenum, but the low-grade deposits are located at the headwaters of the Bristol Bay fishery next to a national park.

Whether to allow the mine and its promise of jobs to go forward has been a fraught proposition even for Alaska Republicans, because it pits three of the state’s biggest industries — fishing, mining and tourism — squarely against each other.

Gov. Sean Parnell, a Republican, could not be reached for comment Friday morning. But he called the EPA’s January scientific assessment of the damage from Pebble Mine “little more than a pretext for an EPA veto of the state’s permitting process.”

And Alaska Senator Mark Begich, a Democrat, gave a mixed grade to the EPA’s announcement that it would initiate Clean Water Act protections.

“While I am a strong supporter of responsible resource development — including mining — I have said the Pebble Mine is the wrong mine in the wrong place,” Begich said in a written statement Friday.

“However, I am skeptical of federal overreach,” he said, “from an administration that has already demonstrated it does not understand Alaska’s unique needs.”

Photo: Todd Radenbaugh via Flickr