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Julie Jacobson, File, Associated Press
FILE - This July 10, 2011 file photo shows the Yellowstone River flowing eastward past the Exxon Mobil refinery, in Laurel, Mont. State officials are calling on federal regulators and the oil and gas industry to provide data on the "invisible spider web" of pipelines crossing Montana waterways in the wake of a spill that dumped tens of thousands of barrels of oil into the Yellowstone River.

HELENA, Mont. — State and federal officials say the most toxic compounds contained in an estimated 50,000 gallons of spilled oil dissipated quickly after last month's Yellowstone River pipeline break.

Gov. Brian Schweitzer and the Environmental Protection Agency said Thursday what was left behind are less volatile gobs of crude.

The EPA and the state released the results of air, water and soil samples taken after the July 1 pipeline break, aiming to alleviate concerns about the risk to public health.

The spill's fumes have sickened some residents. They worried the oil could seep into their drinking water and harm crops and livestock.

One resident, Jim Swanson, says that he's not convinced by the results. He hired a private company to take his own soil and water samples, and is awaiting the results.