US EPA

The Bristol Bay watershed in southwestern Alaska supports the largest sockeye salmon fishery in the world, is home to 25 federally recognized tribal governments, and contains large mineral resources. The potential for large-scale mining activities in the watershed has raised concerns about the impact of mining on the sustainability of Bristol Bay’s world-class commercial, recreational and subsistence fisheries and the future of Alaska Native tribes in the watershed who have maintained a salmon-based culture and subsistence-based way of life for at least 4,000 years. The purpose of the assessment is to provide a characterization of the biological and mineral resources of the Bristol Bay watershed, increase understanding of the potential impacts of large-scale mining on the region’s fish resources, and inform future governmental decisions related to protecting and maintaining the physical, chemical and biological integrity of the watershed. As a scientific assessment, it does not discuss or recommend policy, legal or regulatory decisions, nor does it outline or analyze options for future decisions.

The Bristol Bay watershed in southwestern Alaska supports the largest sockeye salmon fishery in the world, is home to 25 federally recognized tribal governments, and contains large mineral resources. The potential for large-scale mining activities in the watershed has raised concerns about the impact of mining on the sustainability of Bristol Bay’s world-class fisheries, and the future of Alaska Native tribes in the watershed who have maintained a salmon-based culture and subsistence-based lifestyle for at least 4,000 years.

EPA launched this assessment to determine the significance of Bristol Bay’s ecological resources and evaluate the potential impacts of large-scale mining on these resources. EPA will use the results of this assessment to inform the consideration of options consistent with its role under the Clean Water Act. The assessment is intended to provide a scientific and technical foundation for future decision making; EPA will not address use of its regulatory authority until the assessment becomes final and has made no judgment about whether and how to use that authority at this time.

The purpose of this assessment is to understand how future large-scale mining may affect water quality and the Bristol Bay salmon fisheries, which includes the largest wild sockeye salmon fishery in the world. Bristol Bay, Alaska, is home to a salmon fishery that is of significant economic and subsistence value to the people of Alaska and that fishery depends on clean water and a healthy watershed to remain sustainable. The Pebble Limited Partnership and other mining interests are actively exploring large-scale porphyry copper (i.e., gold, copper, molybdenum) mining in the headwaters of two drainage basins in Bristol Bay that provide key habitat for salmon. The analysis will be strengthened by scientific peer review, tribal consultation, federal and state agency participation, as well as public and industry input. EPA will accept and consider public input during development of the watershed assessment and will continue to work closely with tribal governments and state and federal agencies as we undertake this analysis.

It is EPA’s goal to finalize the assessment in 2013, after carefully considering additional public comments, conducting tribal consultations, and assessing input from the expert peer reviewers.

U.S. EPA. An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska (Second External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/910/R-12/004Ba-c, 2013.

Note on PRINTING: To print these files, we recommend that you save the larger files (particularly the full volumes) to your computer for printing rather than printing from the web site. Some of the chapters contain oversize pages. If you do not have access to a printer that can print 11 x 17 pages, please be sure to set page scaling to “shrink to printable area” or “fit to printable area” when printing, which will allow all pages to print on 8.5 x 11 pages. If you have access to a printer that can print 11 x 17 pages, select “choose paper source by PDF page size”, which will allow oversize pages to print at full size.

Note on Comments: Comments on the assessment were submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select Environmental Protection Agency and the key word EPA-HQ-ORD-2013-0189 (for the docket ID).