More information is needed on the construction of the Dakota Access Pipeline under Lake Oahe before the Army Corps of Engineers will decide to approve critical rights, the US Army said yesterday in a joint statement with the Department of the Interior. The Corps will work with the Standing Rock Sioux Tribe, which has been protesting the pipeline for months, on developing a timetable.

On November 8th, the pipeline operator Energy Transfer Partners announced that it was preparing the final phase of construction beneath Lake Oahe, which has been the epicenter of many of the protests. The pipeline operators said they were only awaiting an easement — or, permission to access and drill on the federal land adjacent to the lake — from the government to begin construction. Yesterday’s decision amounts to a delay of that easement.

In July, the US Army Corps of Engineers gave its permission for the Dakota Access Pipeline to cross the disputed reservoir, the major water source for the Tribe. The Standing Rock Sioux Tribe has been protesting the pipeline since April, and sued the Army Corps of Engineers in August for failing to consult them before approving the pipeline’s construction. In September, the Department of Justice, the Department of the Interior, and the Army all agreed that the pipeline’s construction could not continue on the federal land around and under the lake until they reviewed the earlier decision.

The Standing Rock Sioux Tribe say the pipeline may contaminate their water, as well as destroy significant cultural sites. Yesterday’s decision appears to at least begin to address the Tribe’s concerns. More discussion is needed, the Army says, “in light of the history of the Great Sioux Nation’s dispossessions of lands” and “the importance of Lake Oahe to the Tribe.”

The Army has invited the Standing Rock Sioux Tribe to discuss whether the pipeline should be allowed to cross Lake Oahe and, if the pipeline did cross the lake, what safeguards would be needed to prevent or quickly detect a spill were the pipeline to rupture. Construction will be halted while these discussions continue (although the Army intends for the discussions to happen “expeditiously.”)