It came the same day as a planned "day of action" in cities around the U.S. and in other countries, including a rally that drew hundreds in Washington to hear Sen. Bernie Sanders and others speak. Authorities also arrested 22 people for interfering with construction on the pipeline about 70 miles (113 km) northwest of the main protest site near the Standing Rock Sioux Reservation in North Dakota.
Energy Transfer Partners CEO Kelcy Warren told employee the pipeline is nearly 60 percent complete and that "concerns about the pipeline's impact on the local water supply are unfounded." The Standing Rock Sioux tribe and others argue the project will impact drinking water for thousands of tribal members and millions downstream.
"I am confident that as long as the government ultimately decides the fate of the project based on science and engineering, the Dakota Access Pipeline will become operational. ... So we will continue to obey the rules and trust the process," he wrote.
Standing Rock Tribal Chairman Dave Archambault II said he and the thousands of others who have gathered at an encampment in southern North Dakota to protest won't budge.
"People are still coming down here and are committed to stopping the project," he said.
The tribe is challenging the Army Corps of Engineers' decision to grant about 200 permits at water crossings for pipeline, which goes through the Dakotas and Iowa to Illinois. The tribe says the project will disturb sacred sites and impact drinking water. Energy Transfer Partners disputes those claims, saying the pipeline would include safeguards and that workers monitoring the pipeline remotely could close valves within three minutes if a breach is detected.
"We have designed the state-of-the-art Dakota Access pipeline as a safer and more efficient method of transporting crude oil than the alternatives being used today," his memo said.
The tribe's effort to temporarily block construction near its reservation was denied by U.S. District Judge James Boasberg on Friday. But minutes later, federal officials ordered a temporary halt to construction on Army Corps land around and underneath Lake Oahe — one of six reservoirs on the Missouri River. Three federal agencies also asked ETP for a "voluntary pause" in work for 20 miles (32 km) on either side of Lake Oahe.
ETP removed about 30 pieces of damaged or vandalized construction equipment from the area near the protest site Tuesday, according to Morton County Sheriff's Department spokesman Rob Keller. The company did not immediately respond to a request for comment on whether it has halted construction in that section or is backing down on its plans to build the pipeline, but has said construction continues elsewhere.
About 70 miles (113 km) northwest of the main protest site in southern North Dakota, protesters "swarmed" construction workers and two people chained themselves to equipment, according to Morton County Sheriff's Office spokeswoman Donnell Preskey. Twenty people face charges of criminal trespassing, and two who "attached" themselves to equipment also face charges of hindering law enforcement and disorderly conduct, she said.
In Washington, Sanders was joined at the rally by a couple of Standing Rock Sioux members, including a girl who had joined about a dozen people this summer in running a petition signed by 140,000 people from North Dakota to Washington. The speakers encouraged President Barack Obama, who visited the reservation in 2014, to back their cause.
"It is vitally important that we show solidarity with the Native American people of this country," Sanders said. "The second issue of global consequence is that we understand that the future of energy in this country is not more oil, it is not more pipelines, it is not more carbon emissions. It is the transformation of our energy system away from oil, away from pipelines and away from carbon."
Warren's memo noted that because of what it called "misinformation" in the news, the company is working to "communicate with the government and media more clearly in the days to come."
Warren said the company had consulted with more than 55 tribes, including the Standing Rock Sioux, and added that ETP values and respects "cultural diversity and the significant role that Native American culture plays in our nation's history and its future and hope to be able to strengthen our relationship with the Native American communities as we move forward with this project."
Archambault said the consultations were one-sided and that "they met with us after their plans were already made."