Three conservation groups are suing to halt preliminary work on a proposed 1,700-mile-long oil pipeline from the tar sands of western Canada to Texas Gulf Coast refineries.
The lawsuit filed Wednesday in federal court in Nebraska contends that the U.S. Fish and Wildlife Service broke the law by allowing Canadian pipeline operator TransCanada to start preparing the route for its Keystone XL pipeline.
The groups say federal officials allowed TransCanada to clear a 100-mile pipeline corridor through the Nebraska Sandhills, despite a federal law barring projects from launching before they receive approval.
The project would cross the Ogallala aquifer, which supplies groundwater to Nebraska and seven other states.
The lawsuit also names the U.S. State Department, Secretary of State Hillary Clinton and Secretary of the Interior Ken Salazar.