A federal pipeline safety official says inspectors found an "anomaly" in an oil pipeline a month before it ruptured in a Montana river, but the problem was not significant enough to force a shut down. 

Cynthia Quarterman of the U.S. Pipeline and Hazardous Materials Safety Administration told a Senate committee a problem in the Exxon Mobil pipeline was discovered in early June, nearly a month before it ruptured on July 1, spilling an estimated 1,000 barrels of crude into the Yellowstone River.

Quarterman declined to offer specifics about the anomaly, but said officials believed it was "below the required repair conditions."

Montana's Sen. Max Baucus said he was disappointed in the federal response.

He told Quarterman, "To be honest, ma'am, it sounds like you're not on top of this."

Associated Press