Exxon Mobil Corp will bring in more people to mop up oil from a broken pipeline beneath the Yellowstone River as receding floodwaters reveal new contamination, federal officials said Friday.Also Friday, Montana environmental regulators said the pipeline may have leaked up to 1,200 barrels of oil into the scenic river. That equals 50,400 gallons and is 20 percent higher than prior estimates from Exxon Mobil.

Water levels on the Yellowstone have dropped six feet since the July 1 accident. Hundreds of logjams and debris piles, many coated in a layer of drying crude, now litter its banks and islands.