Four Dakota communities in Minnesota are supporting North Dakota’s Standing Rock Sioux Tribe in its efforts to stop a controversial oil pipeline, they announced Friday.

The tribe is challenging the U.S. Army Corps of Engineers’ decision to grant permits for Dallas-based Energy Transfer Partners’ $3.8 billion Dakota Access pipeline, which crosses the Dakotas and Iowa to Illinois, including near the Standing Rock reservation in southern North Dakota. A federal judge will rule before Sept. 9 whether construction can be halted on the pipeline.

The tribe says the project threatens its land, cultural and water resources near the Missouri River.

On Friday, the tribe said it has found several sites of “significant cultural and historic value” along the path of the pipeline.

Tribal preservation officer Tim Mentz said in court documents filed Friday that the tribe was only recently allowed to survey private land north of the Standing Rock reservation.

Mentz said researchers found cairns, burial sites and other features of historic significance to Native Americans.

In their statement supporting the Standing Rock tribe, the Minnesota tribes said:

“This lack of consultation is contrary to the government-to-government relationship between tribes and the federal government. The Upper Sioux, Lower Sioux, Prairie Island and Shakopee Mdewakanton communities urge the United States government to honor this relationship with tribes by reversing the U.S. Army Corps of Engineers’ decision to approve the location of the (Dakota Access Pipeline) Missouri River Crossing and engaging in proper consultation with the Standing Rock Sioux Tribe.’’

This report includes information from the Associated Press.