Exxon Mobil Corp. will pay $1.05 million to settle federal violations for polluting the Yellowstone River in Montana in 2011, when a broken pipeline dumped 63,000 gallons of crude oil 150 miles downstream from Yellowstone National Park.

Last month’s 210,000-gallon oil spill from the Keystone pipeline in South Dakota may have resulted from damage caused during construction, according to a preliminary investigation by the U.S. Dept. of Transportation’s Pipeline and Hazardous Materials Safety Administration.