(Reuters) – The Native American tribes looking to stop the Dakota Access pipeline asked a judge to find that the Army Corps violated federal regulations when it recently granted the last permit needed for the project to be finished, according to a Tuesday court filing.

In a filing in U.S. District Court in Washington, Jan Hasselman, a lawyer with Earthjustice who represents the tribes, said the court should rule, in a partial summary judgment, that the U.S. Army Corps of Engineers violated the National Environmental Policy Act and Clean Water Act by issuing the final permit.

That easement will allow the Dakota Access pipeline to be completed by tunneling under Lake Oahe, a reservoir that forms part of the Missouri River. It comes after Judge James Boasberg on Monday denied the request by the Standing Rock Sioux and Cheyenne River Sioux for a temporary restraining order stopping the last stretch of construction.

Energy Transfer Partners is building the 1,170-mile (1,885 km) line, which will run from North Dakota to Patoka, Illinois. The last permit was denied in December and later subject to further environmental review, by the outgoing Obama administration.

After taking office last month, President Donald Trump ordered that steps be taken to expedite the permit. The Army Corps then elected not to undergo the additional environmental review and issued the permit last week.

The tribes’ legal options are narrowing, according to Dave Archambault II, chairman of the Standing Rock Sioux.

The case is 1:16-cv-1534-JEB, U.S. District Court of Washington, D.C.

(Reporting by David Gaffen; Editing by Leslie Adler)