VANCOUVER, Feb 28 (Reuters) - U.S. environmental regulators moved on Friday to block development of the Pebble mine in Alaska, which could be one of the largest copper projects in the world, citing potential "irreversible harm" to the state's salmon fishery.
The Environmental Protection Agency (EPA) said it has initiated a rarely used process under the Clean Water Act to "identify appropriate options to protect" the Bristol Bay fishery from the impact of the proposed mine.
The decision follows a report in January that found large-scale mining would pose serious risks to salmon and native cultures in the pristine corner of southwest Alaska.
"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 said in a statement.
"This process is not something the agency does very often, but Bristol Bay is an extraordinary and unique resource."
Vancouver-based Northern Dynasty Minerals Ltd, which owns the Pebble project, plans to build a large open-pit mine at the site, which would produce significant amounts of copper and gold for decades to come.
It has said the mine can be built in a safe manner and would provide an economic boom for the State of Alaska.
"We don't see this as an end, in any way, but as a continuation of the process," Northern Dynasty spokesman Sean Magee said.
Magee said that the company remains confident the massive copper-gold project will eventually go ahead.
The EPA could use the Clean Water Act to effectively veto the mine. It has initiated similar processes just 29 times and completed the entire process only 13 times. The review will include a new consultation period, public hearings and further consultations with the Army Corps of Engineers and the company.
Permits cannot be approved during the review process.
The Pebble project is located some 200 miles (320 km) southwest of Anchorage, in a region of Alaska that produces nearly 50 percent of the world's wild sockeye salmon.
Northern Dynasty lost its project development partner last September when mining group Anglo American pulled out of the venture.