BILLINGS — More oil-fouled locations were discovered along the Yellowstone River as floodwaters receded after an Exxon Mobil Corp. pipeline failure, but officials said Monday the geographical extent of pollution along the scenic waterway did not appear to be growing.
A total of 45 locations with oil had been found, an increase of 15 sites since Saturday, said Steve Merritt of the U.S. Environmental Protection Agency.
The number is likely to keep increasing as crews in boats reach areas that previously were inaccessible because of the flooding river.
Yet no new contamination has turned up beyond an isolated spot 70 miles downstream of the July 1 pipeline spill near Laurel.
Most damage is between the spill site and 25 miles downstream, with scattered areas of pollution all the way out to Pompeys Pillar National Monument, about 45 miles downstream, Merritt said.
"The number of sites is going to increase dramatically as we get access to the river," Merritt said. "But it's not getting bigger. Dissipation (of oil) over the length of the river has reduced impacts as you get farther and farther from the spill site."
Exxon Mobil has estimated that up to 1,000 barrels of crude coming from Wyoming spilled into the river when the 12-inch Silvertip Pipeline failed for still-unknown reasons.
Between 1 and 5 percent of the spilled oil has been recovered. Most of the remainder is not expected to be found, Merritt said.
More than 100 claims have been submitted to Exxon Mobil from individuals claiming property damage, agricultural losses and health problems, company spokeswoman Cynthia Berfman White said. A breakdown of those claims was not immediately available.
Despite reports of people sickened by the fumes coming off the crude, officials say air and water monitoring to date suggest there should be no long-term health concerns.
The EPA plans to test drinking water from several hundred residential wells downstream of the spill as a precaution.
A work plan submitted by Exxon Mobil detailing its cleanup plan will have to be revised after the EPA said the company provided insufficient information on oil recovery and containment and remediation for impacted areas downstream and for the area around the spill site.
A revised work plan is due by July 17, said Montana Department of Environmental Quality deputy director Tom Livers.
"So far we haven't seen any effort to take shortcuts," Livers said. "The proof will be when we're really done with the work plan and can make sure the state's cleanup standards are in there."
Meanwhile, a five-person team of oil spill experts from California began arriving Sunday in Montana to assist the state in its response to the spill.
Livers said the team from the California Department of Fish and Game would provide an independent source of expertise.