Uranium company enCore Energy said a US Environmental Protection Agency (EPA) board rejected a challenge from Native American and environmental groups over permits for its Dewey Burdock in-situ recovery uranium project in South Dakota, advancing the mine closer to development.

The EPA’s Environmental Appeals Board (EAB) denied a petition from the Oglala Sioux Tribe, Black Hills Clean Water Alliance and NDN Collective, the company said Tuesday in a statement. The ruling upholds the agency’s earlier decision to grant Class III and Class V Underground Injection Control permits for the project.

“This decision by the EAB affirms the validity of the permits and the integrity of the regulatory process following years of administrative and judicial review,” said Robert Willette, acting CEO of Dallas-based enCore. “The Dewey Burdock project is part of enCore’s US production pipeline, and today’s decision provides the certainty needed to continue advancing toward development.”

The project, which has been tied up in regulatory reviews and litigation for more than a decade, is now in possession of all major federal authorisations, including a source materials licence from the Nuclear Regulatory Commission. enCore plans to begin state permitting in 2025.

The Dewey Burdock development was also accepted last month into the federal Fast-41 permitting programme, created to accelerate reviews of infrastructure and critical mineral projects deemed important for US energy security.

Located in Custer and Fall River counties, the mine would use in-situ recovery, which dissolves uranium underground using a water-based solution and pumps it to the surface for processing. The company says the technique limits surface disturbance compared with traditional openpit or underground mining.

Willette said the outcome “not only strengthens enCore’s growth strategy but also underscores our role in delivering secure, domestic uranium supply critical to America’s clean energy and national security future".