Pebble Mine's challenge to EPA reaches an Anchorage court Thursday.

A federal judge in Anchorage hears arguments Thursday over whether to throw out the EPA's 2023 decision blocking key parts of the proposed Pebble Mine.

The hearing is scheduled for June 25 before U.S. District Judge Sharon L. Gleason in Northern Dynasty Minerals Ltd. v. EPA.

Northern Dynasty and Pebble Limited Partnership are asking the court to vacate EPA's final determination under Section 404(c) of the Clean Water Act — the rarely used federal authority EPA invoked to restrict mine-related discharges into the Bristol Bay watershed. The State of Alaska and Iliamna Natives Ltd. have filed related challenges. Trout Unlimited, the United Tribes of Bristol Bay, the Bristol Bay Native Corporation, and several other tribal, conservation, and commercial-fishing groups have entered the case as intervenors on EPA's side.

EPA issued the determination on Jan. 30, 2023, concluding certain dredged-or-fill discharges associated with developing the Pebble deposit would cause "unacceptable adverse effects" on salmon fisheries in the Bristol Bay watershed. The agency restricted use of waters in the South Fork Koktuli, North Fork Koktuli, and Upper Talarik Creek drainages as disposal sites for mine-related material. According to EPA, the 2020 mine plan would have permanently eliminated about 8.5 miles of anadromous fish streams, 91 additional miles of supporting streams, and roughly 2,100 acres of wetlands. EPA said the action applies only to discharges tied to the Pebble deposit, not to other Alaska resource projects.

It was not the first federal action against the project. The U.S. Army Corps of Engineers denied a key permit in 2020. Alaska tried to take its challenge directly to the U.S. Supreme Court in July 2023; the Court declined to hear it in January 2024, sending the case back to lower courts. Thursday's hearing is the result.

Northern Dynasty, Pebble's parent company, has called the EPA action a "veto." In its 2023 annual report, the company said the determination "is unlawful, is not supported by the record before the Agency, and represents an unprecedented overreach of EPA authority under the Clean Water Act." The company has also said any future mine would remain subject to major permitting, financing, engineering, and legal risks.

The hearing does not decide whether a mine will be built. It decides whether the 2023 EPA determination survives.

Bristol Bay supports one of the world's largest sockeye salmon runs and the tribes, communities, and commercial and sport fisheries built around it. EPA and most regional tribal, fisheries, and conservation groups argue a Pebble development would damage that system; Northern Dynasty and the State of Alaska argue a mine can be built responsibly through ordinary permitting. The lawsuit is, at bottom, about whether EPA had authority to make that call without waiting for permitting to play out. It is also a rare test of EPA's Section 404(c) authority that could shape how the agency applies it to other resource projects nationwide.