JUNEAU (AP) — A consortium of tribes is seeking to intervene in support of the U.S. Environmental Protection Agency in a lawsuit challenging EPA’s authority to potentially block the proposed Pebble Mine.

United Tribes of Bristol Bay petitioned EPA in 2010 to look at the potential impacts the project could have on the Bristol Bay watershed. EPA earlier this year concluded that large-scale mining in the region posed significant risk to salmon. And the agency initiated a rarely used process through which it could restrict or prohibit development of the Pebble deposit.

The group behind the Pebble project has asked a judge to halt that process, pending the outcome of this case. The Pebble Limited Partnership and state fear EPA could veto the project before a permit is even filed.