Exxon claimed failed pipeline was buried deep below Yellowstone River

BILLINGS — Exxon Mobil Co. had reassured federal regulators and officials from a Montana town since December that an oil pipeline beneath the Yellowstone River was safe, buried deep enough to avoid any accidental ruptures.

Then, on Friday night, the pipe failed, spilling an estimated 42,000 gallons into the flooded river.

The cause of the accident remains under investigation, but the prevailing theory among officials and the company is that the raging Yellowstone eroded the riverbed and exposed the line to damaging rocks or debris.

There is still no definitive word on how far downriver the spill could spread.

Oil has fouled miles of the waterway that flows from the famed Yellowstone National Park, upriver from the spill, and across farmlands and prized fishing grounds, to North Dakota. There have been confirmed reports of oil as far as 80 miles downstream, although most appears to be concentrated in the first 25 miles.

At an Environmental Protection Agency meeting Wednesday night, about 150 people showed up with questions about health risks, the duration of the cleanup, and whether the oil will permanently damage their livestock or property.

George Nilson, 69, said the fumes from oil that wash through his neighbor's property had been overwhelming. He said it took several days of calling a spill hot line before he got a response.

"Why the slow response?" asked Nilson, who lives outside of Billings. "I've been in it for five days now and the only way I can breathe is to have all the windows open."

An EPA representative said the agency may to indoor air sampling after hearing several complaints such as Nilson's.

As residents along the river deal with an oil-smeared shoreline and workers clean up the mess, the accident has raised concerns about the impact that the season's floods may be having on the network of pipelines buried under riverbeds.

"It's too early to tell whether this is an isolated incident or there might be other types of increased damage or erosion based on a year of flooding," said Brigham McCown, a former federal pipeline safety official who now advises pipeline companies at a Dallas firm.