Exxon Mobil under the terms of a joint agreement settled for $12 million for the 2011 oil spill that spoiled a section of the Yellowstone River, officials said.

About 1,500 barrels of oil leaked in July 2011 into the Yellowstone River near Billings, Mont., from the 12-inch Silvertip pipeline. Scouring of the pipeline, which was about 4 feet below the river bottom, was suspected of contributing to the rupture of Silvertip at a time of heavy flooding in the river.

Montana Gov. Steve Bullock, state Attorney Gen. Tim Fox, along with the U.S. Departments of Justice and Interior, said Exxon's pipeline division agreed to pay $12 million for natural damages tied to the spill.

"Montanans deserve and expect ExxonMobil Pipeline Co. to be held accountable for the damages they caused to Montana's Yellowstone River, our communities, and our economy," the governor said in a statement. "This proposed settlement goes a long way in protecting Montana's Yellowstone River, one of the last, great, free-flowing rivers in the United States that plays a vital role in our strong $6 billion outdoor economy."

The Montana Department of Environmental Quality said Exxon had completed all of the supplementary environmental projects associated with the spill early last year. That effort included more than $1.3 million spent on projects aimed at restoring the river's ecosystem.

The U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration in its investigation into the spill said the company failed to address the risks of river flooding, scour and erosion to its Silvertip pipeline system.

About 1,000 barrels of oil spilled in January last year from the Poplar Pipeline near the Yellowstone River in Glendive, Mont. Water restrictions were in place for area residents after a spill from that pipeline system.

The state of Montana said it was still reviewing a draft restoration plan for the 85 river miles and associated floodplain damaged by the Silvertip pipeline rupture.

Exxon had no public statement available on the settlement.