The litigation challenged the EPA's July 2019 decision to withdraw its prior regulatory action under Section 404(c) of the Clean Water Act, initiated in 2014 by the Obama Administration, which sought to pre-emptively veto the Pebble project before permit applications had been filed or an Environmental Impact Statement (EIS) permitting process was undertaken.

In granting the motion to dismiss, judge Sharon Gleason found the anti-Pebble activists had "failed to state a claim upon which relief can be granted".

The Pebble project can now continue to be vetted under the National Environmental Policy Act's permitting process. Currently, the mine's federal permit application is pending with the US Army Corps of Engineers, and the EPA retains the right to veto the permit, a power that was reaffirmed by the federal judge's ruling.

Pebble Limited Partnership CEO Tom Collier said the court decision removed another obstacle to receiving a final EIS and Record of Decision on the Pebble project by mid-2020.

The Pebble project proposal has been a bone of contention in the region for the past few years, in particular with regards to its potential risk to the watershed and salmon fisheries. A leaked draft report of the EIS suggested in February that the nearby water resources could co-exist with the mine.

The Defence Alliance, a group comprising the Bristol Bay Native Association, United Tribes of Bristol Bay, Bristol Bay Regional Seafood Development Association, Bristol Bay Reserve Association and Bristol Bay Economic Development Corporation continued to believe the EPA's move to withdraw was contrary to the scientific and public record. The Defence Alliance said it would continue working to secure permanent protections for the Bristol Bay fishery.

Pending permitting, Pebble is one of the world's largest undeveloped gold-copper deposits, holdingan estimated measured and indicated resource of 6.5 billion tonnes containing 57 billion pounds copper, 71Moz gold, 3.4Blb molybdenum and 345Moz silver.

Shares in Northern Dynasty closed 8% higher on Monday at C78c, which capitalises the company at $340.5 million (US$241 million).