Teams made up of federal and Exxon Mobile workers are trying to contain damage from an oil spill in the Yellowstone River near Laurel, Montana.
An Exxon Mobile pipeline broke, causing tens of thousands of gallons of crude oil to spill into the river.
The spill has forced cities and irrigation districts to close intakes across eastern Montana.
The company estimated that up to 1,000 barrels, or 42,000 gallons, spilled late Friday night before the flow from the damaged pipeline was stopped.
Exxon Mobile spokesman Alan Jeffers said 125 workers were on the ground Monday cleaning up scattered sections of riverbank that received crude. But he added that there was no longer a defined slick of oil moving down the river and the impacts were unlikely to grow.
"It's unlikely there's any oil in the water at this point," Jeffers said. "That doesn't mean we know where it all is."
Officials in Yellowstone County were working with the company to connect cleanup personnel with affected property owner, Commissioner John Ostlund said.
Officials speculate high water levels exposed the 12-inch oil pipe causing it to break.
The pipeline delivered about 40,000 barrels of crude a day to a refinery in Billings, was shut down in May because of concerns over rising waters following heavy rains in Eastern Montana, Exxon Mobil Pipeline Co. president Gary Pruessing said Sunday.
State officials said the long-term concern was a disruption to the smaller organisms in the river that larger fish and birds depend on for their food supply.
Exxon Mobil on Monday said only one case of wildlife damage had been reported, which Ostlund said was a goose with oil on it. A local newspaper, the Billings Gazette has run pictures of a turtle and a group of pelicans apparently with oil on them.