The US Supreme Court has refused to hear Alaska’s appeal to overturn the federal Environmental Protection Agency (EPA)’s decision to reject the development of the Pebble Project in the state.

Pebble is a copper-gold-molybdenum porphyry deposit that is being proposed to be developed in southwest Alaska by Canada-based Northern Dynasty Minerals.

Last year, the EPA utilised a rarely invoked authority provided by the Clean Water Act to halt the mine proposal.

The proposed mine’s intended location in the Bristol Bay watershed, as indicated by data on the EPA’s website, is the largest sockeye salmon fishery globally. This area is also inhabited by 25 federally recognised indigenous communities, dependent on salmon for over half of their subsistence harvest.

Last year, Alaska appealed to the justices to consider its challenge to the EPA’s ruling, contending that the highest court had the authority to address the case before lower courts. However, the request was declined by the court without providing any comment.

As per Northern Dynasty Minerals, the current resource estimate for the Pebble Project comprises 6.5 billion tonnes in the measured and indicated categories, along with 4.5 billion tonnes in the inferred category.

These resources encompass substantial quantities of copper, molybdenum, gold, and silver in billions of pounds and millions of ounces, respectively, along with millions of kilograms of rhenium. The deposit also contains palladium.

The project, if developed, was anticipated to create nearly 2,000 jobs in Alaska, in addition to generating revenues for the state government.

Northern Dynasty Minerals, via its wholly-owned subsidiary Northern Dynasty Minerals, has been advocating for the development of the deposit as an open-pit mine, along with the necessary infrastructure. The company’s strategy involves extracting approximately 1.5 billion tons of mineralised material over the 20-year lifespan of the mine.