Dakota pipeline builder says oil could flow in as little as 2 weeks Announcement comes amid legal battle between company and Indian tribes.

 -- On the eve of the deadline for Dakota Access pipeline protesters to vacate camps in North Dakota, the company in charge of construction said in a court filing on Tuesday that oil could start flowing in as little as two weeks — sooner than previous estimates.

Texas-based developer Energy Transfer Partners, the builder of the pipeline, said in the filing to the U.S. District Court for the District of Columbia that the company "estimates and targets that the pipeline will be complete and ready to flow oil anywhere between the week of March 6, 2017, and April 1, 2017."

The court filing was required as part of an ongoing legal battle over the pipeline's construction near and under Lake Oahe — which has sparked protests since August.

North Dakota Gov. Doug Burgum last week called for the Oceti Sakowin protest camp — on the edge of the Standing Rock Sioux Reservation — to be evacuated by Feb. 22, claiming ecological damage at the camp and rising post-winter floodwaters.

The Cheyenne River Sioux Tribe, which is part of the Great Sioux Nation, has joined the Standing Rock Sioux Tribe's lawsuit against the pipeline, filing a motion at the D.C. District Court on Feb. 9 seeking a temporary restraining order to halt construction and drilling under and on either side of the lake.

The tribe argued that the pipeline "will desecrate the waters upon which Cheyenne River Sioux tribal members rely for their most important religious practices and therefore substantially burden the free exercise of their religion," according to a court document obtained by ABC News.

Last week the court denied that motion. On Tuesday, Energy Transfer Partners said the Cheyenne River Sioux Tribe's legal claim under the Religious Freedom Restoration Act "has no chance of success on the merits."

The tribe filed a separate motion seeking a preliminary injunction directing the Army Corps of Engineers to withdraw the easement issued to the pipeline company on Feb. 8. The tribe alleges that the easement is "entirely unlawful," according to court documents. A further hearing on the Cheyenne River Sioux's motion for a preliminary injunction against the pipeline is set for Feb. 27 in Washington, D.C.

After receiving the easement to build the pipeline across land on both sides of Lake Oahe, Energy Transfer Partners announced it would resume construction immediately, and work has resumed. The four-state Dakota Access pipeline will connect production areas in North Dakota to an existing crude oil terminal near Patoka, Illinois.

The Standing Rock Sioux Tribe has been at the forefront of massive and prolonged protests over the pipeline. The demonstrations have drawn thousands of Native Americans, environmental activists and their allies to the Standing Rock Sioux Tribe reservation.

Kelcy Warren, the CEO of Energy Transfer Partners, has said that "concerns about the pipeline's impact on local water supply are unfounded" and "multiple archaeological studies conducted with state historic preservation offices found no sacred items along the route."

In the final days of Barack Obama's administration, Jo-Ellen Darcy, the assistant secretary of the Army for civil works, announced on Dec. 4 that an easement would not be granted for the pipeline to cross under Lake Oahe, a large reservoir on the Missouri River.

The move to deny the easement was hailed by the Standing Rock Sioux Tribe and other pipeline opponents as a major victory. But on his second weekday in office, President Trump signed a memorandum aimed at advancing the Dakota Access pipeline, as well as one directed at the Keystone XL pipeline.

ABC News' Luis Martinez, Darren Reynolds, Evan Simon, Catherine Thorbecke and Morgan Winsor contributed to this report.