Federal Judge James Boasberg, who originally ordered Dakota Access Pipeline to empty all the oil while a 13-month environmental analysis is being made, now wants the U.S. Army Corps of Engineers to detail options by the end of the month for resolving the loss of a permit.

The environmental permit was originally granted to allow Dakota Access to cross under Lake Oahe, the source of drinking water for the Dakota Sioux tribe.

The Corps is exploring four options, including some that would not require it to shut down, said Ben Schifman, an attorney representing the Army Corps. The Corps had asked for 60 days to secure the information, but Boasberg said the agency had to present its findings by the end of the month.

Interstate Energy Partners, the parent company of the 570,000 BOPD crude oil pipeline running from Stanley, ND to Illinois, said it would cost millions of dollars to shut down Dakota Access and drain the line.

The District Court of Appeals allowed the pipeline, the biggest out of North Dakota’s Bakken shale region, to continue to flow for the time being.