BISMARCK, N.D. — A federal judge is set to deliver a key ruling on the four-state Dakota Access pipeline that has drawn thousands of protesters to a construction site in North Dakota in recent weeks.

U.S. District Judge James Boasberg said he will rule by the end of Friday on the Standing Rock Sioux tribe’s request to block the $3.8 billion project, which will carry oil from North Dakota to Illinois.

The tribe argues the project threatens water supplies and has already disrupted sacred sites. The developer, Dallas-based Energy Transfer Partners, says modern technology allows quick detection of leaks. Pipeline supporters also say it would cut the amount of oil that travels by train.

A weekend confrontation between protesters and private security guards left some guards injured and some protesters with dog bites.

The Great Plains Tribal Chairman’s Association asked U.S. Attorney General Loretta Lynch on Thursday to send federal monitors to the protest site, alleging racial profiling and other transgressions are happening.

“Our people have a right to peacefully assemble and protest on federal lands,” association President John Yellow Bird Steele wrote.

Authorities say some protesters are armed with hatchets and knives, and Saturday’s clash injured guards and dogs.

Lynch’s office did not immediately respond to a request for comment.