When nearly 42,000 of gallons of crude oil rushed down the Yellowstone River July 1, the Environmental Protection Agency said its first concern was human health.
Individuals and communities downstream of the spill who have long used it as a clean drinking water source must now await results as the agency tests their wells for oil-related pollutants.
Officials in Custer County, three counties down from the spill site, said they received late notice of the spill and risk to water treatment plants. (They didn't find out until the morning after.) But as soon as they became aware of it, municipalities and irrigation districts closed their water intakes. According to Reuters, public water supplies to Billings and Lockwood, Mont. were reopened soon after the spill and a preventative closing of their water pipes, because officials deemed them safe.
Three days after the spill, water tests conducted in five locations on the Yellowstone River between Laurel, Mont. and Miles City, Mont. found that petroleum chemical levels had not exceeded drinking water standards.Though testing has so far turned up nothing out of the ordinary, those domestic water wells, which mainly draw from groundwater, are still under scrutiny.
“We want to screen every drinking water well within the heaviest affected area between Laurel and Billings as quickly as possible and move down river from there,” Steve Merritt, on-scene coordinator said in a July 10 press release.
The agency has no idea how many domestic water wells it will test in the coming days to ensure the public’s drinking water supplies are safe, just an idea of which areas to target.
“We’re going downstream to every residential property and asking permission to test their domestic water wells,” Jim Martin, the agency's regional coordinator, said.
As of Thursday morning, four sampling teams had completed 42 well tests, said agency spokesman Matthew Allen. Hundreds of wells in the area near the spill could be affected, including domestic ones for homes and businesses, the agency says.
Martin said water tests will continue on the first 27 miles downstream of the spill, where the agency has seen the most contamination. That covers wells between the spill site and Lockwood. all within Yellowstone County, though others have spotted oil by helicopter up to 70 miles from the spill.
“Given the relationship of water to oil, we actually think it’s very unlikely that the groundwater’s been contaminated,” Martin said of wells in the test area and those further downstream.
Kimberly Hirai is an intern at High Country News.
Image of the Laurel water treatment plant courtesy U.S. Fish and Wildlife Service.