Pipeline

The company plans to begin at northern Montana's border with Canada.

The groups contend the approval of the pipeline project in November violated the Endangered Species Act.

The move pushes the controversial $8 billion project closer to construction, but it still faces court challenges.

Texas-based Denbury Resources plans to build the pipeline in 2020 and began injecting carbon dioxide in early 2021.

The company and regulators said the cause was being investigated.

Opponents filed a lawsuit arguing the company didn't follow all the required procedures for the route that was approved.

It's designed to move 350,000 barrels of oil daily from western North Dakota's oil patch to Cushing, Oklahoma.

The carbon dioxide would come as a byproduct from a pair of natural gas processing plants.