Large-scale mining in the Bristol Bay watershed poses serious risks to salmon and native cultures in this pristine corner of southwest Alaska, the U.S. Environmental Protection Agency said in a report released on Wednesday.
The EPA said a mine could destroy up to 94 miles of salmon-supporting streams and thousands of acres of wetlands, ponds and lakes. The report focused on the impact of mining in an area where a Canadian-based company wants to build a large copper and gold mine.
Polluted water from the mine site could enter streams, causing widespread damage in a region that produces nearly 50 percent of the world's wild sockeye salmon, the EPA said.
The Bristol Bay region supports all five species of Pacific salmon found in North America, which include sockeye, Chinook, chum, coho and pink salmon. It is also home to bears, moose and caribou.
There is also the risk of accidents and pipeline failures that could release toxic copper concentrate or diesel fuel into salmon streams or wetlands, the EPA said.
The report, which concludes a three-year study and follows two drafts that also warned of widespread ecological damage from mining, does not recommend policy or regulatory decisions.
Northern Dynasty Minerals Ltd's Pebble project would develop an open-pit mine in the region, which has one of the world's largest copper-gold deposits.
The Vancouver-based company was swift to condemn the report, and said the EPA had repeatedly failed to meet its own guidelines and policies for watershed assessments, risk assessment and peer review.
The company vowed to press on with the project, located some 200 miles southwest of Anchorage. Northern Dynasty lost its project development partner last September when mining group Anglo American pulled out of the venture.