BILLINGS, Mon.—Exxon Mobil will pay $1.6 million in penalties to the state of Montana over water pollution caused by a pipeline break last summer that fouled miles of shoreline along the Yellowstone River.
Montana Department of Environmental Quality director Richard Opper said the penalties in the case mark the largest in the agency’s history.
The Texas oil company will pay $300,000 in cash and spend $1.3 million on future environmental projects.
Exxon also increased its estimate of how much crude spilled into the river in the July 2011 accident near Laurel to 1,509 barrels—more than 238,000 litres.
That’s up from earlier estimates of 1,000 barrels spilled.
Only about 10 barrels of crude were recovered by cleanup crews, federal officials have said—less than one per cent of the total spilled.
The cause of the spill remains under investigation.
The 12-inch Silvertip pipeline was buried just a few feet beneath the riverbed when it was installed 20 years ago. High water last spring and summer eroded the cover, which could have exposed the line to damaging debris.
The settlement requires continued monitoring of environmental damage by Exxon and for the company to clean up any more oil that is discovered, which includes any crude stirred up when the Yellowstone rises again in the spring as mountain snow begins to melt.
Testing of river sediments near public water supply intakes also will be required.
Exxon will reimburse more than $760,000 in emergency response costs racked up by state agencies.