Two U.S. senators from Montana are urging federal safety regulators to wrap up a study into whether oil spills from pipelines into rivers, lakes and other water bodies resulted from the lines being inadequately buried.
    
Democrats Max Baucus and Jon Tester said in a recent letter to the Department of Transportation the agency must do a better job of analyzing risks to pipelines.
    
The Democrats say such work is crucial to preventing accidents such as a 2011 Exxon Mobil pipeline break near Laurel. That accident spilled 1,500 barrels of crude into the flooding Yellowstone River and revealed that many pipelines beneath rivers are threatened by erosion.
    
A Transportation Department spokesman says regulators are working to meet a Jan. 3 deadline to deliver results of the pipeline crossings study to Congress.