Interior Secretary Ken Salazar Wednesday approved a “land-into-trust” application submitted by the Three Affiliated Tribes of the Fort Berthold Reservation in western North Dakota to build the first U.S. refinery in decades — in the heart of the Bakken shale formation.

Construction of the $400 million refinery proposed by the Mandan, Hidatsa and Arikara (MHA) tribes may begin as early as next spring, and it may take 12 to 18 months to complete, the Associated Press reported.

The facility, which will officially be called the MHA National Clean Fuels Refinery, would be the first new refinery built in the United States in more than 30 years, according to Interior. The 13,000 b/d facility would refine Bakken crude oil into products including diesel fuel and propane. It eventually would have a capacity of up to 20,000 b/d, with the diesel staying in North Dakota.

The tribes asked Interior’s Bureau of Indian Affairs (BIA) to accept a 469-acre piece of property into trust, with the proposed refinery to sit on 190 acres and the remaining acreage to be used for the production of feed for the tribes’ buffalo herd. Interior would own the land, while the tribes would manage it.

Future federal permitting and oversight will be handled by the U.S. Army Corps of Engineers, Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration.

The BIA and the EPA co-led the final environmental impact review of the refinery project, which was completed in 2009. The EPA issued a National Pollution Discharge Elimination System permit for the refinery in August 2011, which is required under the Clean Water Act. The permit lists the required conditions and limitations for the proposed refinery’s operations.

A 30-day notice of Interior’s decision to acquire the land in trust will be published in the Federal Register.