Authorities struggled on Sunday to gauge the environmental and crop damage from tens of thousands of gallons of oil that spilled into the legendary Yellowstone River, as Montana's governor criticised ExxonMobil for downplaying the possible scope of the disaster.
A break in a company pipeline near Laurel fouled kilometres of riverbank and forced municipalities and irrigation districts to close intakes across eastern Montana.
ExxonMobil brought in more cleanup workers to mop up crude at three sites along the flooded river that were coated with thick globs of crude. Yet there was no clear word on how far the damage extended along a scenic river famous for its fishing and vital to farmers who depend on its water for their crops.
The uncertainty frustrated riverfront property owners such as Linda Corbin, who worried that severe damage would be revealed as the flooding Yellowstone recedes in coming weeks. The stench of spilled crude was obvious in Corbin's backyard — a reminder of the potential problems lurking beneath the surface of the nearby river.
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"The smell has been enough to gag a maggot," said Corbin. "I just hope it doesn't come too far because I'm on a well, and I won't appreciate having to shower in Exxon oil."
Environmental Protection Agency spokeswoman Sonya Pennock said its staff had spotted oil at least 40 kilometres downstream. There were other reports of oil as far as 200 kilometres away, near the town of Hysham.
After ExxonMobil Pipeline Co. president Gary Pruessing said flyovers had shown most of the damage was limited to a 20-kilometre stretch of river, Governor Brian Schweitzer dismissed the claim as premature.
The Democratic governor said ExxonMobil needed to get more personnel to inspect the situation close-up. He also slammed Pruessing's statement to reporters that no injured wildlife had been found.
"For somebody to say at this early stage that there's no damage to wildlife, that's pretty silly," Schweitzer said. "The Yellowstone River is important to us. We've got to have a physical inspection of that river in small boats — and soon."
Exxon estimated that up to 1,000 barrels, or 42,000 gallons, spilled on Saturday before the flow from the damaged pipeline was stopped. An EPA representative said only a small fraction of the spilled oil was likely to be recovered.
State officials earlier reported a 50-kilometre long slick headed downstream towards the Yellowstone's confluence with the Missouri River, just across the Montana border in North Dakota. Authorities had no further reports on that slick, and Pruessing said the oil appeared to be evaporating and dissipating as the Yellowstone carries it downstream.
Pruessing also said that the 12-inch pipeline had been temporarily shut down in May because of concerns over the rising waters on the Yellowstone. He said the company decided to restart the line after examining its safety record and deciding the risk was low.
The US Department of Transportation, which oversees pipelines, last year issued a warning letter to ExxonMobil that cited seven safety violations along the ruptured Silvertip pipeline. Two of the warnings faulted the company for its emergency response and pipeline corrosion training.
Transportation Department spokeswoman Patricia Klinger said the company has since responded to the warnings and the case was closed.
The company and government officials have speculated that high waters in recent weeks may have scoured the river bottom and exposed the pipeline to debris that could have damaged the pipe. Eastern Montana received record rainfall in the last month and also has a huge snowpack in the mountains that is melting, which has resulted in widespread flooding.
"We are very curious about what may have happened at the bottom of the river. We don't have that yet," Pruessing said.
Crews were putting absorbent material along short stretches of the river in Billings and near Laurel, but no attempts were made at capturing oil farther out. In some areas, oil flowed underneath booms.
EPA on-scene coordinator Steve Way said fast flows along the flooding river were spreading the oil over a large area, making it harder to capture.