A federal judge last week ordered Ruby Montoya, a 32-year-old climate activist, to serve six years in prison for her role in damaging the Dakota Access Pipeline

More than 380,000 gallons of oil have spilled from a leak in the Keystone pipeline in North Dakota this week, officials said.

For months, the International Indigenous Youth Council, known for its commitment to peaceful action, has helped steer the Standing Rock Sioux Tribe's efforts to halt the Dakota Access pipeline.

TransCanada, the pipeline's owner, said the leak is under investigation.

Oil could flow through the pipeline as soon as next week.

Indigenous activists erected a tipi camp beside the Washington Monument today.

Trump has said Keystone steel "comes from the U.S., or we're not building it."

Protests took place for months in an attempt to stop the Dakota Access pipeline from being built next to the Standing Rock Sioux Tribe reservation.

The legal opinion was withdrawn two days before an easement was approved.

The Dakota Access pipeline protest site has been cleared after some demonstrators refused to leave Wednesday, when a deadline for evacuation passed.

Forty-six people were arrested today, authorities said.

Police clad in full riot gear have entered the main encampment of people protesting the Dakota Access pipeline near Cannonball, North Dakota, where some protesters remained despite state and federal orders to leave.

Harold Frazier and his team traveled to D.C., when they presented a temporary restraining order against the DAPL on Feb. 13 and reviewed the original treaties the U.S. signed with the Great Sioux Nation.

People have gathered at the Oceti Sakowin camps in North Dakota to protest construction of the Dakota Access pipeline.

The deadline to evacuate the Oceti Sakowin camp was Wednesday at 2 p.m.

Officers arrested at least 10 protesters who refused to leave a North Dakota campsite and have warned the area will soon flood and any trash and debris left behind may become hazardous to rivers.

Protesters set fire to temporary structures they built as authorities try to negotiate.

ABC News' Phillip Mena reports from the area where protesters are refusing to leave as they reach their deadline.

Announcement comes amid legal battle between company and Indian tribes.

Dakota Access pipeline protesters at the Standing Rock Sioux Tribe reservation in North Dakota met with state representatives Thursday.

The camp needs to be evacuated by February 22.

Tribe joins a motion filed Thursday by Cheyenne River Sioux Tribe.

A judge found no irreparable harm to the tribes if construction goes on.

ABC News' Maggie Rulli reports from Washington talking to Leaders of Standing Rock.

A Native American tribe has filed the first legal challenge to block the nearly finished Dakota Access Pipeline from moving forward.

Opponents of the Dakota Access Pipeline believe the easement cannot be granted legally at this time.

The controversial final phase of the pipeline has been on hold.

An overview of the fight between the Standing Rock Sioux Tribe and Energy Transfer Partners.

The Army said it has not yet granted the easement needed to finish the pipeline.

"As you know, I approved two pipelines that were stuck in limbo forever," President Donald Trump said during his remarks at a listening session with county sheriffs. "I don't even think it was controversial."

The Army Corps of Engineers could reach a decision as early as this week on whether to grant an easement to the Dakota Access pipeline, according to an attorney for the government on Monday.

A court hearing is scheduled for early next week.

Record levels of snow are expected in the area, which could compromise safety.

The company seeks to protect the pipeline from potential terrorists.

About 76 "rogue" protesters were arrested Wednesday near the Dakota Access Pipeline in North Dakota, authorities said.

The Morton County Sheriff's Department posted a video of officers clearing protesters' camp on private property in North Dakota.

About 20 protesters were arrested after refusing to disperse from the property.

The actions drew applause from pipeline supporters, condemnation from opponents.

President Trump used his fifth day in office to move forward the Keystone and Dakota Access pipelines, as well as to streamline regulations for infrastructure and manufacturing.

ABC News photographed Red Cloud’s visit in December to the Standing Rock Reservation where he installed solar air furnaces to help keep protesters warm.

Army Corps has denied the easement needed to finish the controversial pipeline.

Native-American groups and environmental activists have been protesting since summer to block construction of the nearly completed 1,172-mile pipeline.

Protesters have been ordered to leave the area by today.

Stars cheer decision by Army to deny approval for Dakota Access Pipeline.

At least 2,000 veterans arrived at the protests this afternoon.

Authorities have warned that protesters would be arrested starting Monday.

As evacuation deadline looms, veterans and civil rights observers converge.

Actress criticized the holiday and treatment of Native Americans over centuries.

For Native American activists, Thanksgiving brings back difficult memories.

Broken treaties are at the heart of the protests at Standing Rock.