U.S. Army Corps of Engineers announced Sunday that plans for the $3.8 billion Dakota Access Pipeline to cross under Lake Oahe in North Dakota have been halted.

“Although we have had continuing discussion and exchanges of new information with Standing Rock Sioux and Dakota Access, it’s clear that there’s more work to do,” Jo-Ellen Darcy, the Army’s assistant secretary for civil works, said in a statement. “The best way to complete that work responsibly and expeditiously is to explore alternative routes for the pipeline crossing.”

The proposal was the focus of protests over the last few months as the Standing Rock Sioux Tribe and supporters argued the pipeline would threaten the water source and way of life. The reservation is a half-mile south of the proposed pipeline crossing.

“Today, the U.S. Army Corps of Engineers announced that it will not be granting the easement to cross Lake Oahe for the proposed Dakota Access Pipeline. Instead, the Corps will be undertaking an environmental impact statement to look at possible alternative routes. We wholeheartedly support the decision of the administration and commend with the utmost gratitude the courage it took on the part of President Obama, the Army Corps, the Department of Justice and the Department of the Interior to take steps to correct the course of history and to do the right thing," Standing Rock Sioux Tribal Chairman Dave Archambault II said in a statement.

Gov. Jack Dalrymple referred to the Army Corps' decision as a "serious mistake" while U.S. Rep. Kevin Cramer called it a "very chilling signal" for the future of America's infrastructure.

U.S. Attorney General Loretta Lynch announced that the Department of Justice will continue to keep watch over North Dakota with efforts to "provide resources" for anyone who "can play a constructive role in easing tensions."

Bernie Sanders, a proponent for preserving the sacred land tweeted his thanks to the Obama administration once the decision was made public.

In addition to the thousands of cheering demonstrators at Standing Rock, allies issued praise on Twitter.

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