DOON, Iowa (AP) — A freight train derailed in northwest Iowa on Friday, leaking crude oil from at least one of 31 tankers into flooded fields flanking the tracks and raising concerns about the possible contamination of residential water supplies, officials said.
BNSF railroad spokesman Andy Williams said no one was injured when the cars derailed around 4:30 a.m. Friday just south of Doon in Lyon County.
Officials at the scene aren't sure whether floodwater from the swollen Little Rock River caused the cars to leave the tracks. The river rose rapidly Wednesday after 5 to 7 inches (13 to 18 centimeters) of rain fell Wednesday and a further downpour on Thursday.
A broadening sheen of oil spread near several of the tankers, which had piled up across the track and earthen berm, some submerged in the water.
Williams said he was unsure how much oil leaked and how many of the cars were leaking. Lyon County Sheriff Stewart Vander Stoep said the oil was being carried downstream into the Rock River a few hundred yards west of the derailment.
No information was immediately available on how much oil each of the tankers was carrying. Cleanup crews were dispatched to the site.
Vander Stoep said four homes near the site have been evacuated.
The Rock River has already carried some oil to Rock Valley, nearly 5 miles (8 kilometers) southwest of the derailment, said Ken Hessenius with the Iowa Natural Resources Department. State crews are trying to determine how fast the oil was travelling south. The Rock River joins the Big Sioux River before merging into the Missouri River at Sioux City.
The task difficulty is compounded by the spreading floodwater, he said.
"The river, instead of being 100 yards wide, is now maybe a half-mile wide" in spots, Hessenius said.
"Our first major concerns are public water supplies," he said, adding that several towns that draw water from shallow wells near the Rock River have been alerted about possible contamination.
Doon is about 40 miles (65 kilometers) southeast of Sioux Falls, South Dakota, where several rain-swollen rivers overflowed Thursday. The National Weather Service has forecast flooding in the area into the weekend.