The Standing Rock and Cheyenne River Sioux tribes were in court last week in a last-ditch legal effort to stop completion of Energy Transfer Partners’ Dakota Access Pipeline.

Construction on the final segment of the pipeline began last Thursday, after the company received an easement from the U.S. Army Corps of Engineers to begin laying pipe under Lake Oahe, a reservoir along the Missouri River in North Dakota.

Water “is our life,” said Cheyenne River Sioux Chair Harold Frazier. “It must be protected at all costs.”

On Thursday, the community asked a federal judge to halt work on the project until another suit against the project concludes. Attorney Nicole Ducheneaux said the project would “desecrate the waters” on which the Cheyenne River Sioux depend. “The sanctity of these waters is a central tenet of their religion, and the placement of the pipeline itself, apart from any rupture and oil spill, is a desecration of these waters,” she wrote.

U.S. District Judge James Boasberg was to hold a status hearing on the request today.

Standing Rock Sioux Chair David Archambault said his community would continue its legal battle “against an administration that seeks to dismiss not only our treaty rights and status as sovereign nations, but the safe drinking water of millions of Americans.”