In a memo to employees, Energy Transfer Partners chief executive Kelcy Warren vowed to finish building the controversial Dakota Access pipeline, which the Standing Rock Sioux tribe says will disturb sacred ground in North Dakota and adversely affect drinking water for the tribe and those further downstream.

The $3.8 billion project stretches across 1,172 miles and through four states. There is opposition from the Standing Rock Sioux and several other groups, with many protesting near the tribe's reservation and calling for an end to the construction. But Warren disagrees, The Associated Press reports, writing on Tuesday that the project is nearly 60 percent finished and that "concerns about the pipeline's impact on the local water supply are unfounded." He also said the company has "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," and will work to "communicate with the government and media more clearly in the days to come."

Thousands of people have protested the pipeline in North Dakota, and 22 were arrested Tuesday 70 miles northwest of the main protest site for interfering with construction. The Justice Department and Army Corps of Engineers have halted construction on a part of the pipeline near the Standing Rock Sioux reservation, but hundreds of people gathered in Washington, D.C., for a demonstration, including Sen. Bernie Sanders (I-Vt.), who said: "It is vitally important that we show solidarity with the Native American people of this country. The second issue of global consequence is that we understand that the future of energy 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." Catherine Garcia