Wednesday, the U.S. Environmental Protection Agency released its final Bristol Bay Assessment describing potential impacts to salmon and ecological resources from proposed large-scale copper and gold mining in Bristol Bay. The report, titled "An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska," concludes that large-scale mining in the Bristol Bay watershed poses risks to salmon and Alaska Native cultures.

“Over three years, EPA compiled the best, most current science on the Bristol Bay watershed to understand how large-scale mining could impact salmon and water in this unique area of unparalleled natural resources,” said Dennis McLerran, Regional Administrator for EPA Region 10. “Our report concludes that large-scale mining poses risks to salmon and the tribal communities that have depended on them for thousands of years. The assessment is a technical resource for governments, tribes and the public as we consider how to address the challenges of large-scale mining and ecological protection in the Bristol Bay watershed.”

The report pointed to the risks involved with routine operation of a large mine, which included the large footprint of the mine and estimated that 24 to 94 miles of salmon-supporting streams and 1,300 to 5,350 acres of wetlands, ponds, and lakes would be destroyed. EPA estimates an additional 9 to 33 miles of salmon-supporting streams would experience altered streamflows likely to affect ecosystem structure and function.

The EPAS listed waste and waste water as another factor in their decision. They stated that extensive quantities of mine waste, leachates, and wastewater would have to be collected, stored, treated and managed during mining and long after mining concludes. Also included in the assessment was the possibility of water collection and treatment failures that they estimate would impact 48-62 miles of streams in the region.

Also included was the possibility of culvert failures,runoff and chemical spills as well as pipeline failures that could potentially release toxic copper concentrate and diesel fuel into streams as well as tailings dam failure.

Bristol Bay supports the largest sockeye salmon fishery in the world, producing nearly 50 percent of the world’s wild sockeye salmon with runs averaging 37.5 million fish each year.

The assessment found that the Bristol Bay ecosystem generated $480 million in economic activity in 2009 and provided employment for over 14,000 full and part-time workers. The region supports all five species of Pacific salmon found in North America: sockeye, coho, Chinook, chum and pink. In addition, it is home to more than 20 other fish species, 190 bird species, and more than 40 terrestrial mammal species, including bears, moose and caribou.

In 2010, several Bristol Bay Alaska Native tribes requested that EPA take action under the Clean Water Act to protect the Bristol Bay watershed and salmon resources from development of the proposed Pebble Mine, a copper, gold and molybdenum mining venture backed by Northern Dynasty Minerals Ltd. Other tribes asked EPA to wait for a mine permitting process to begin before taking action on the potential environmental issues Pebble Mine presents.

In response to the release of the EPA assessment, CEO of the Bristol Bay Native Corporation, Jason Metrokin said, “From the very beginning, EPA was in Bristol Bay because our federally recognized Tribes and Native organizations, including BBNC, asked them to be. With today’s release, science has weighed-in: Bristol Bay, its existing jobs and way of life could be irreparably damaged by a large-scale mine that is the size and scope of the Pebble project—and therefore, our fish, our people and our cultures must be protected.

“BBNC supports responsible development where it can be done without causing unacceptable risks to the people, cultures and fishing economy of our region. The proposed Pebble mine is not such a project. It’s time for the agency to initiate a 404(c) action to protect Bristol Bay.”

The Pebble APartnership CEO, John Shively released a comment on Wednesday addressing the assessment. He called the assessment a flawed document and stated that “It must be remembered that the report does not assess the effects of the Pebble Project as we have not finalized nor submitted a project for regulatory evaluation. The report is based upon a so-called ‘hypothetical mine’ of the EPA’s design.”

“EPA did not take the time nor did it commit the financial resources to assess the potential impacts of development in an area the size of the state of Ohio.” said Shively. Shively went on to say, “Unfortunately the real loss is for stakeholders, especially those in Southwest Alaska who are seeking ways to fully understand modern mining and the range of issues posed by possible development of Pebble.”

Alaska’s top politician responded to the assessment. “Unfortunately, today’s EPA report comes as no surprise to Alaskans,” Governor Sean Parnell said. “This report is little more than a pretext for an EPA veto of the state’s permitting process, something the federal Clean Water Act prohibits. As my record demonstrates, I will not trade one resource for another, and every permitting application—when filed—deserves scientific and public scrutiny based on facts, not hypotheticals.”

State Representative Les Gara had this to say. “No one wants the feds to do the state’s work, but Governor Parnell wouldn’t stand up for the state on Pebble. The governor should have taken action to protect the world’s greatest wild salmon and trout streams. The feds unfortunately had to come in to do what Governor Parnell refused to do—protect Alaska’s sport, subsistence and commercial fish. I’d rather have had the state exercise its sovereignty and protect Bristol Bay. But the Governor effectively called on the feds to do his job,” said Gara.

“Between weakened clean water rules from the Murkowski era, and the governor’s new bill to allow unsustainable amounts of water to be taken from our fishing streams, this governor is doing what he promised he wouldn’t—trading one resource for another,” Gara continued.

Alaskan Senator Mark Begich also weighed in on the assessment stating, “I have always said I will let science be my guide, and my decision whether to support the Pebble project will be based on this report,” said Begich. “The stakes are high for Alaska – I have heard from thousands of Alaskans on this issue – and that is why I will be thoroughly reviewing the final watershed assessment and continuing to rely on science for any final decision.”

EPA maintained an open public process, reviewing and considering all comments and scientific data submitted during two separate public comment periods. The agency received approximately 233,000 comments on the first draft of the assessment and 890,000 comments on the second draft.

The agency reviewed information about the copper deposit at the Pebble site and used data submitted by Northern Dynasty Minerals Ltd. to the U.S. Securities and Exchange Commission, including the document titled “Preliminary Assessment of the Pebble Project, Southwest, Alaska,” which provides detailed descriptions of three mine development cases representing 25, 45 and 78 years of open pit mining. The 45-year development scenario was presented as the reference case in the Northern Dynasty report.

The EPA’s Final Assessment can be read here. (PDF)