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, Alaska.
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. 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.
“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.”
To assess potential mining impacts to salmon resources, EPA considered realistic mine scenarios based on a preliminary plan that was published by Northern Dynasty Minerals Ltd. and submitted to the U.S. Securities and Exchange Commission. EPA also considered mining industry references and consulted mining experts. Numerous risks associated with large-scale mining are detailed in the assessment:
Risks from Routine Operation
Mine Footprint: Depending on the size of the mine, EPA estimates 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.
Waste and Wastewater Management: Extensive quantities of mine waste, leachates, and wastewater would have to be collected, stored, treated and managed during mining and long after mining concludes. Consistent with the recent record of similar mines operating in the United States, polluted water from the mine site could enter streams through uncollected leachate or runoff, in spite of modern mining practices. Under routine operations, EPA estimates adverse direct and indirect effects on fish in 13 to 51 miles of streams.
Risks from Accidents and Failures
Wastewater Treatment Plant: Short and long-term water collection and treatment failures are possible. Depending on the size of the mine, EPA estimates adverse direct and indirect effects on fish in 48 to 62 miles of streams under a wastewater treatment failure scenario.
Transportation Corridor: A transportation corridor to Cook Inlet would cross wetlands and approximately 64 streams and rivers in the Kvichak River watershed, 55 of which are known or likely to support salmon. Culvert failures, runoff, and spills of chemicals would put salmon spawning areas in and near Iliamna Lake at risk.
Pipeline: Consistent with the recent record of petroleum pipelines and of similar mines operating in North and South America, pipeline failures along the transportation corridor could release toxic copper concentrate or diesel fuel into salmon-supporting streams or wetlands.
Tailings Dam: Failure of a tailings storage facility dam that released only a partial volume of the stored tailings would result in catastrophic effects on fishery resources.
Press Release, January 16, 2014