A Native American tribe is at the center of an historic dispute in North Dakota, over an oil pipeline project they say threatens their main source of water.

The Dakota Access Pipeline would carry approximately 500,000 barrels of crude oil from the Bakken and Three Forks production area through four states, ending in Illinois. A portion of the pipeline would also pass 90 feet under the Missouri River, a water source for the Standing Rock Sioux tribe.

Ron His Horse Is Thunder, a former chairman for the Standing Rock Sioux tribe, is concerned.

“If this pipeline is built and it breaks-and it will break, maybe not tomorrow may be 20 years from now, it will break.  We estimate it will take about 20 minutes to get to our first water intake.”

The project is temporarily on hold, after three federal agencies ordered the company, Energy Transfer Partners, to halt construction on a portion of the project near the tribal land until further review.

The tribe worries that the pipeline would also disturb ancient and sacred Native American sites. Thousands have descended on the region to support their cause.

“We’re not opposed to energy independence,” Tribe Chairman David Archambault told CNN’s Jake Tapper. “This is a long history of problems that evolved over time where the federal government or corporations take advantage of indigenous lands and indigenous rights – these injustices that we’re experiencing have been happening over and over and over again. What we’re opposed to is paying for all the benefits that this country receives, paying the cost.”

Labor unions are pushing back, saying workers will be out of until construction resumes. According to Rep. Kevin Cramer, North Dakota’s only congressman and member of the House Committee of Energy and Commerce, there are too many parties involved.

“The issue is can we keep this between the pipeline company, the Army Corps of Engineers and the Standing Rock Sioux tribe where we have a lot of reasonable people that I think can work it out. the challenge comes with the large out of state national entities, even international entities, whose agenda is perhaps different, clearly different from Standing Rock’s who have legit questions about the proximity of the pipeline”

At issue is whether the Army Corps of Engineers erroneously granted a permit to Energy Transfers to build the Dakota Access pipeline just half a mile from the Standing Rock Sioux’s reservation under Lake Oahe. The tribe holds that the Army Corps of didn’t listen to their complaints. The Army Corps of Engineers holds that the tribe didn’t attend all of the meetings, but that the tribe’s concerns were taking into consideration.

While the project undergoes a review, Cramer believes it is unfair to the company which legally obtained every permit required prior to the start of the construction phase. However, he is open to discussing how the process can be improved to avoid conflicts in the future.

“The government consultation process is really what’s at debate,” Cramer says. “I think the problem is going to be, now, where it’s become retroactive and the admin’s pulled the permit and said we’re going to review our process and maybe we have to do this again a different way.”

Check out our video for an on-the-ground look at the protest encampment and watch Cramer’s full interview here.