---- — BILLINGS, Mont. (AP) — Delays in Exxon Mobil Corp.'s response to a major pipeline break beneath Montana's Yellowstone River made an oil spill far worse than it otherwise would have been, federal regulators said in a new report.
The July 2011 rupture fouled 70 miles of riverbank along the scenic Yellowstone, killing fish and wildlife and prompting a massive, months-long cleanup.
The damage could have been significantly reduced if pipeline controllers had acted more quickly, according to Department of Transportation investigators.
The report, provided to The Associated Press by the office of Montana U.S. Sen. Max Baucus, marks the first time federal regulators have highlighted specific actions by Exxon as contributing to the severity of the spill.
An Exxon spokeswoman said Wednesday the company was reviewing the findings.
The spill released about 63,000 gallons of crude from Exxon's 20-year-old Silvertip pipeline into the river near the city of Laurel. That damage would have been reduced by about two-thirds if controllers in Houston isolated the rupture as soon as problems emerged, investigators said.
Instead, after Exxon personnel partially shut down the line and were weighing their next steps, crude drained from the severed, 12-inch pipeline for another 46 minutes before a key control valve was finally closed.
Exxon spent $135 million on its response to the spill, including cleanup and repair work.
Spokeswoman Rachael Moore said the company will continue to cooperate with Pipeline and Hazardous Materials Safety Administration and "is committed to learning from these events."
The report chalks up the immediate cause of the spill to floodwaters that damaged the pipeline and left it exposed. Debris washing downriver piled up on the line, increasing pressure until it ruptured.