By Liz Hampton

HOUSTON (Reuters) – Energy Transfer Partners has filed a motion to bar the U.S. Army Corps of Engineers from initiating an environmental study for its controversial Dakota Access pipeline crossing at Lake Oahe in North Dakota.

Energy Transfer Partners requested on Monday that a U.S. District Court judge for the District of Columbia stop the Corps from initiating the environmental impact statement process until a ruling has been made on whether the company already has necessary approvals for the pipeline crossing.

The Corps said it would publish a notice in the Federal Register on Wednesday stating its intent to prepare an environmental impact statement for the requested easement at Lake Oahe. The notice will invite interested parties to comment on potential issues and concerns, as well as alternatives to the proposed route, which should be considered in the study.

The Corps in December denied Energy Transfer Partners an easement to drill under Lake Oahe, a water source upstream from the Standing Rock Sioux reservation that has been the focus of protests. Members from the Standing Rock Sioux and others say the line could damage drinking water and desecrate sacred grounds.

In July 2015, the Corps had granted Energy Transfer Partners permission for its proposed pipeline crossing at Lake Oahe.

A representative from Energy Transfer Partners did not immediately respond on Tuesday to a request for comment.

The 1,172-mile (1.885 km) Dakota Access Pipeline will transport 570,000 barrels per day of crude from the Bakken shale of North Dakota to the Midwest.

The Standing Rock Sioux said the tribe was confident the environmental impact statement would support its claim that the pipeline cannot cross under the lake, adding that the best way to analyze new routes is through an environmental impact statement.

Comments on the scope of the environmental impact statement will be due no later than Feb. 20, the Army Corp said.

(Reporting by Liz Hampton; Editing by Dan Grebler)