The U.S. Environmental Protection Agency announced Monday a scientific review of Alaska’s Bristol Bay watershed, to “better understand how future large-scale development projects” might impact the greatest salmon fishing area in America.

The EPA responded to a request by the Bristol Bay Native Corp. and nine federally recognized Bristol Bay Alaska native tribes, which asked the agency to use its authority under the Clean Water Act to protect the Bay.

Native groups are fearful of the Pebble Mine, a giant gold-copper-molybdenum mine proposed between two of Bristol Bay’s major salmon spawning streams and just west of Alaska’s largest lake.

“By 2006 estimates, the open pit mine would be two miles wide and produce up to 2.5 billion tons of acid-generating waste rock and discharged chemicals,” the Bristol Bay Native Corp. said in requesting the review.

The EPA’s Seattle-based Region 10 administrator, Dennis McLerran, said Monday: “The Bristol Bay watershed is essential to the health, environment and economy of Alaska.”

“Gathering data and getting public input now, before development occurs, just makes sense. Doing this we can be assured that our future decisions are grounded in the best science and information and in touch with the needs of these communities.”

Seattle-based fishing interests are major players in Bristol Bay. A bevy of distinguished Seattle restaurants — Ray’s Boathouse, the Steelhead Diner, Andaluca, and Flying Fish — have joined opposition to the proposed mine.

A major Seattle jewelry retailer, Ben Bridge Jewler, has joined Tiffany & Co. and other major firms in a pledge never to source their gold from the Pebble Mine.

The EPA did not give the Alaska natives all that they requested. The assessment does not represent “any regulatory decision by the agency,” EPA Region 10 said in a news release.

“The agency declined to launch a formal effort to consider blocking disposal of mining waste in waterways downstream of the Pebble deposit: The agency said it might — or might not consider taking that step in the future,” the Anchorage Daily News reported.

The EPA assessment will focus primarily on the Nushagak and Kvichak watersheds, both close to the proposed mine. “Most of the Bristol Bay watershed is wildlife refuge or park where large development is restricted: EPA’s efforts will focus on those areas that are not protected,” the agency said.

The Clean Water Act gives EPA power to veto disposal of dredgings or the filling of waterways. The authority has been infrequently exercised in the 39 years since President Richard Nixon signed the landmark environmental law.

U.S. Rep. Don Young, R-Alaska, an ally of the mining industry, has introduced legislation to revoke the EPA veto power under the Clean Water Act.

Young blasted the EPA on Monday, saying it is “blatantly circumventing” toe state of Alaska’s permit process, and describing the agency’s action as part of a “romper-room style” of the bama administration.

But Sens. Lisa Murkowski, R-Alaska, and Mark Begich, D-Alaska, had generous words for the EPA in choosing to evaluate potential dangers to Bristol Bay rather than preemptively blocking the Pebble Mine on grounds of waste disposal.

The Bristol Bay Native Corp. was a major supporter of Sen. Murkowski’s successful 2010 write-in campaign to retain her Senate seat. Murkowski took more than 70 percent of the vote in Bristol Bay-area native villages.

The Pebble Mine plans to store tailings waste in artificial lakes, restrained by earthen dams. The largest of the dams, by 2006 estimate, would be 740 feet tall and 4.3 miles long. The mine would require an 80-mile-long road to a port facility on Cook Inlet.

Two of America’s major national parks, Katmai and Lake Clark National Parks, are close to the mine site.