Crews spent Saturday containing the spill and building a temporary road to move equipment to the crash site to make it easier to remove the piled-up train cars and advance the cleanup, the Sioux City Journal reported. Roughly 100,000 gallons has been contained with booms in a low-lying area filled with floodwaters near the derailment.
Sheriff Vander Stoep said, "There is so much food for the workers and for us at the incident command, it's just wonderful how little these communities come together".
The derailment of 32 oil tanker cars Friday just south of Doon has caused concern for towns and cities downstream, as far south as Omaha, Nebraska, about 150 miles from the derailment site. The river rose rapidly after 13 to 18 cm of rain fell in the days prior to the derailment.
Rock Valley, with a population of almost 3,400, sits on the Rock River about five miles (8.05 kilometers) downstream from the derailment site.
The cause has not been confirmed, although Iowa Governor Kim Reynolds attributed it to an intense storm and flash flooding in an emergency proclamation issued by her office on Saturday. "The long-term cleanup will take a while, a matter of months, probably, and we will be working hand in hand with the EPA and other agencies".
Williams said he was unsure how much oil leaked and how numerous cars were leaking. The train was carrying oilsands from Alberta, Canada, to Stroud, Oklahoma, for ConocoPhillips.
Metropolitan Utilities District said it was monitoring pumps it uses to pull drinking water from the Missouri. ConocoPhillips spokesman Daren Beaudo said each tanker can hold more than 25,000 gallons (20,817 imperial gallons) of oil.
Rock Valley, just southwest of the derailment, shut off its water wells within hours of the spill.
Cities downstream from the spill are monitoring their water systems.
Danger from the spill has been exacerbated by recent rainfall, which has caused the Rock River to overflow its banks along the route of the train tracks.
Beaudo said Saturday that the derailed oil cars were a model known as DOT117Rs, indicating they were newer or had been retrofitted to be safer and help prevent leaks in the event of an accident.