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Critics blast U.S. study finding huge Alaskan mine poses little environmental risk

A massive mine proposed for the heart of a vast Alaskan wilderness won’t hurt ecosystems there, including the world’s largest run of sockeye salmon, the U.S. Army Corps of Engineers (USACE) announced today. But opponents of the proposed Pebble Mine, including environmental scientists, say the analysis is deeply flawed.

The new findings are a victory for backers of the mine, which has been the subject of extensive controversy. The report clears the way for the mining company to get the federal permits it needs to start to dig what could become one of the world’s largest gold and copper mines. USACE could approve permits as soon as late August, although the company must also acquire permits from the state government, which could take longer.

“After a lengthy misinformation campaign many were led to believe a mine at Pebble would harm the fishery. Today’s report from the USACE turns that lie on its head,” says Tom Collier, CEO of the Pebble Partnership, the company behind the mine plan.

But critics say the report, which differs little from an earlier draft that received pointed criticism from some of the government’s own scientists, ignores years of research findings. “The science is overwhelmingly clear: The proposed Pebble Mine is a catastrophe waiting to happen,” says National Wildlife Federation President Collin O’Mara.

USACE’s environmental impact study says the mine would damage 160 kilometers of fish habitat and 18 square kilometers of streams and wetlands. In a landscape laced with rivers draining an area the size of Virginia, the agency concluded the mine “would not be expected to measurably affect the health or value” of the lucrative salmon fishery in nearby Bristol Bay, which is worth some $300 million annually.

The decision marks a dramatic reversal for the mine under President Donald Trump. In 2014, under then-President Barack Obama, the project appeared all but dead after the Environmental Protection Agency (EPA) announced it would block federal permits to fill wetlands, concluding the mine posed too great a threat to the environment. But after Trump came to office, EPA withdrew the finding and USACE, which issues the wetland permits, moved forward with its study.

Mine promoters tried to navigate environmental concerns by scaling back its original mine proposal, while holding out the possibility of enlarging the mine later. In today’s announcement, USACE embraced that approach, focusing on the potential impacts of the smaller mine footprint.

Can mining and salmon coexist?

The proposed Pebble Mine (bottom) would straddle two major salmon-producing watersheds in Alaska’s Bristol Bay. Critics of the mine fear that, if permitted, it would open the door to expansive development in the region.

Environmental Protection Agency’s maximum estimate of the Pebble Mine 0 20 Km Lake Iliamna Lake Clark Cook Inlet Iliamna Newhalen Pedro Bay Port Alsworth Nondalton Igiugig Kokhanok Lake Clark National Park Mining claims 0 200 Km Kenai Peninsula Gulf of Alaska Bristol Bay Cook Inlet Homer Seward Kenai Iliamna Anchorage Wasilla Platinum Kodiak Island Lake Nerka Nushagak River Lake Iliamna Dillingham Pacific Ocean
A. CUADRA/SCIENCE

In that scenario, the mine would run for 20 years, extracting 1.4 billion tons of rock from a pit deep enough that it could just fit the tallest tower in New York City, One World Trade Center. The most problematic waste rock—which can produce acidic water runoff—would be stored behind a dam during the mine’s life, then buried in the mine pit, according to the mining company.

The new report’s findings did not change significantly from an earlier draft that drew complaints from mine opponents and other federal agencies, including EPA and the National Marine Fisheries Service. The Interior Department warned that the draft study was so inadequate that USACE should rewrite major portions.

A chief concern is the lack of a detailed analysis of the potential long-term effects of an expanded mine. Mine critics warn that the most valuable cache of minerals lies outside the area highlighted in the mining company’s reduced proposal. “Really the decision that’s being made here is whether to turn the incredibly productive Bristol Bay watershed into a vast mining district, because that’s what's going to happen,” says Joel Reynolds, a senior attorney for the Natural Resources Defense Council.

If the entire deposit were mined, the mine could operate for 80 years, and create a pit two-thirds as deep as the Grand Canyon, according to a scenario studied by EPA. Lakes of toxic mine waste nearly big enough to cover Manhattan would be held in place behind huge dams expected to survive for thousands of years in a region that routinely experiences earthquakes.

The mine site lies on a bench between two major Bristol Bay drainages that together produce roughly one-quarter of the sockeye runs on a typical year. Although the mine covers a tiny fraction of Bristol Bay watersheds, salmon advocates fear a failure of any dams holding mine waste could devastate much larger swaths of the fishery.

In its decision, USACE predicts relatively small impacts from a mine waste spill, saying the dams the company is proposing to build have a safer design than conventional mine waste dams. In addition, the study notes, the most problematic waste would be buried in the mine pit after the mine closes.

Mine critics also point to decades of research that have found Bristol Bay’s productivity is linked to having a smorgasbord of different spawning streams. In a typical year, roughly 40 million fish turn vast stretches of rivers and creeks red with the scarlet bodies of sockeye returning to spawn in the streams and lakes where they hatched.

The concentration of salmon spawning varies across the landscape from year to year as conditions change in individual streams, spreading the risk much like an investor buys a variety of different stocks. As a result, even insults to a smaller number of streams could ripple through the entire ecosystem, scientists have warned. “The whole is more than the sum of its parts,” says Daniel Schindler, a University of Washington, Seattle, scientist who has led much of the research there. “The Pebble EIS [environmental impact statement] utterly fails at appreciating this.”

Numerous groups, including fishing industry associations, Alaskan tribes, and environmental organizations, are expected to file lawsuits challenging any permits issued based on USACE’s findings.