ANCHORAGE, Alaska, April 26 (Reuters) - Digging a large mine in southwest Alaska would inflict widespread ecological damage, the U.S. Environmental Protection Agency said in a report on Friday that could hurt the chances of a proposed project in that region winning regulatory approval.
A large scale open-pit mine in Alaska's unspoiled Bristol Bay region would destroy up to 90 miles (145 km) of salmon and trout spawning streams, harm thousands of acres of wetlands that support fish and subject local waters to chemical spills and releases of untreated wastewater, the EPA report said.
The report did not specifically analyze the plan for Pebble Mine, the project proposed for the area, because developers have not officially made permit applications. But it studied the implications of a hypothetical project similar to Pebble. (EPA report:)
Pebble Mine, located 200 miles (322 km) southwest of Anchorage, would be one of the world's largest open-pit copper mines. Developers have described it as a potential economic boon that would target both known and anticipated reserves of 80 billion lbs (36.3 billion kg) of copper, over 100 million ounces (2.8 million kg) of gold and 5.5 billion pounds (2.5 billion kg) of molybdenum.
But the latest EPA report predicted a wider scope of environmental damage than outlined in a draft report the agency released last year.
The EPA's conclusion drew a pointed reaction from the mine's developer, Pebble Limited Partnership President John Shively, who called the latest version of the assessment "flawed" and a waste of public money.
Shively in a statement blasted EPA for what he said was a decision to heed mine opponents' demands for a "pre-emptive veto" before development plans are final.
Even "the threat of a 'pre-emptive veto' will introduce uncertainty into the process that threatens to hurt the entire U.S. economy, not just a proposed mine in Alaska," Shively said.
The new EPA assessment backs up the previous draft report's conclusions about stream and wetlands damages, but gives more details about expected damages from roads, culverts, traffic accidents and other industrialization that would likely accompany mine development.
The EPA has made no decision about whether to invoke its legal powers to block the Pebble Mine, said Dennis McLarren, Pacific Northwest regional director for the agency.
The new report will be used to make any decisions about Bristol Bay protections, McLarren said in a conference call.
"We want to better understand the delicate ecological balance the produces the extraordinary fish and wildlife resources in Bristol Bay and assess the risk that mining could pose to that balance," he said.
Developers have already spent $680 million on the Pebble Mine project and plan to spend another $80 million this year, co-owner Northern Dynasty Minerals Ltd said this week. The other owner and Pebble partner is mining giant Anglo American.
The Pebble Mine plan has drawn fury from commercial and sport fishermen, Alaska Natives and environmentalists.
It is upstream from waters that hold the world's largest sockeye salmon runs and other rich marine life, including endangered whales and other vulnerable marine mammals. On land, national wildlife refuges and parks are nearby.