Newhalen River in Alaska’s Bristol Bay.
Braided River Channels: The gravel bottoms and braided channels of rivers leading into Iliamna Lake in southwest Alaska are ideal for the many king salmon that spawn in the lake's waters. © 2008 Ami Vitale

Stories in Alaska

Science to Guide Conservation in Bristol Bay

This globally important landscape is in peril. Learn how we are taking a stand.

This page was updated on Nov. 25, 2020.

Everything runs on wild salmon in Alaska’s Bristol Bay. Nature runs on salmon. Communities. Business and industry. Salmon is the basis of millennia-old Indigenous traditions. The lands and waters of Bristol Bay produce more wild salmon than anywhere else on Earth and that fuels a sustainable commercial salmon fishery valued at $1.5 billion annually. 

Bristol Bay is home to half of the Earth’s wild sockeye salmon. Why? It’s the wealth of healthy streams and rivers, wetlands and lakes. This mix of pristine habitat creates a diverse genetic portfolio of several hundred discrete sockeye salmon populations — and this diversity is key to productivity and long-term sustainability. 

Bristol Bay’s portfolio of genetic diversity — much like a diverse investment portfolio — contributes to a more resilient salmon system and bolsters local fishery-dependent economies. Wiping out or harming any of these discrete salmon populations puts the productivity of the larger Bristol Bay salmon system at risk over time.

But this vital, globally important salmon run is in danger; and the next six months may be our last, best chance to save Bristol Bay. The proposed Pebble mine would straddle the pristine headwaters of the Nushagak River and Kvichak River, spawning grounds for 50% of Bristol Bay’s salmon. Pebble mine would be one of the largest open-pit mines in the world, extracting billions of tons of copper, gold, and molybdenum ore to the irreparable harm of the surrounding landscape.

To protect this globally significant diversity of wild salmon populations and the people who depend on them, TNC is working with a broad coalition of partners to emphasize that the development of Pebble would cause unacceptable risk to people and nature. We are implementing a federal and state influence strategy to prevent and eliminate the threat of current and future large-scale mining in Bristol Bay and support a regional vision for a sustainable, equitable and thriving future for local communities.

Join us to speak out in opposition of Pebble Mine. Contact your federal representatives.

Leading with Science

The Nature Conservancy has invested in a science-led process to assess the risk of developing the proposed Pebble mine in the headwaters of two of the planet's most productive wild salmon rivers. This research led to an influential 2010 resolution on large-scale mining in Bristol Bay which was authored by the Board of Trustees of The Nature Conservancy in Alaska. The proposed Pebble mine does not meet this standard identified in the resolution, and for this reason TNC stands opposed to the project.

Since the Pebble mine was proposed for the headwaters of the Nushagak and Kvichak rivers in the early 2000s, The Nature Conservancy, tribal environment programs, and other research organizations have compiled thorough inventories of the region’s salmon streams, hydrology, traditional use areas, water quality and more.

See our 2019 assessment of direct loss of salmon streams, tributaries and wetlands under the proposed mine plan. We compared the thresholds of unacceptable adverse effects to salmon streams as outlined in the EPA's proposed determination to the Clean Water Act, Section 404(c).

Current Status

The Pebble Mine was first proposed more than a decade ago for the headwaters of the Nushagak and Kvichak rivers in Bristol Bay in southwest Alaska. In late 2017, the Pebble Limited Partnership submitted a 20-year mine plan in its permit application to the U.S. Army Corps of Engineers. That plan, which was updated in 2018, included filling thousands of acres of wetlands and destroying tens of miles of salmon streams — initiating a formal review process through the National Environmental Policy Act or NEPA.  

The U.S. Army Corps of Engineers released its Final Environmental Impact statement on July 24, 2020, paving the way for this project to move toward federal permitting.

The impact statement failed to adequately address key scientific questions formally presented by the Conservancy and many others during the review process. The developers’ own science reveals that their plan vastly exceeds acceptable scientific thresholds and will cause irreparable harm to this valuable landscape, Alaska Native communities, and a globally important fishery.

Join us to speak out in opposition of Pebble Mine. Contact your federal representatives.

The mine would cause significant destruction to salmon habitat in Bristol Bay watersheds, with some impacts exceeding scientific thresholds by more than double. This damage would result from the mine’s construction and early operations, and impacts rise exponentially when analyzing the long-term implications for water quality and the need for toxic wastewater management in perpetuity—through unproven, highly complex systems and technologies.

The Corps' statement also does not account for a potential failure of the mine’s dams to contain toxic waste. Standard industry practice dictates such an assessment, yet the Army Corps did not evaluate this critical scenario. This is not just scientifically inadequate, it is irresponsible given that the mine would be located in a seismically active area and would generate an extremely large quantity of contaminated mine tailings. TNC’s scientific analysis, in partnership with the Bristol Bay Regional Seafood Development Association, revealed that a small dam breach would deposit tailings in 155 miles of streams and salmon habitat, and a large breach would send tailings 80 miles downstream, impacting 200 miles of salmon habitat and flowing clear out to the bay.

See our assessment of the risk of tailings dam failure in Bristol Bay salmon headwaters.

Fortunately, on Nov. 25, 2020, the U.S. Army Corps of Engineers denied the the Pebble Mine's request for key federal permits that would have allowed the project to proceed. The federal decision came amid overwhelming opposition from Bristol Bay communities and a broad coalition of diverse voices united in support for Bristol Bay and its remarkable wild salmon tradition and thriving fishery. 

We are now speaking out to urge the EPA to exercise its authority to veto the proposed Pebble mine under provisions of the Clean Water Act. Further, we call on Congress to ensure the scientific integrity of the Clean Water Act and support the use of sound science to fully identify the serious risks of proceeding with such a project in a fully functioning and healthy Bristol Bay ecosystem. It's also essential that Congress seek a permanent solution and support a regional vision for a sustainable, equitable and thriving future for Bristol Bay communities.

TNC is working with a broad coalition to oppose the development of Pebble mine and its resulting risks to salmon, their habitat and the people and economies that depend on them.

Take Action

Contact your legislators and tell them to oppose Pebble mine.

Take Action