The Iowa Department of Natural Resources is investigating a possible fuel or oil spill that was discovered Friday on the east side of Credit Island and is in the main channel of the Mississippi River.

Iowa DNR official Bert Noll said Friday that a resident noticed the substance and called authorities.

“We’re not exactly sure what it is other than it looked like an oil of some kind,” Noll said. “We were only able to trace it back to the storm culvert that it came from.”

The old storm drain is located on the north side of Credit Island which is on the city side, he said. North of there is an industrial area.

Noll said on Monday he will begin working with Davenport city staff to see if they can trace the source of the substance from the storm drain to its source.

It is difficult to estimate how much of the substance is in the water, he said. “A drop can make it look like it’s everywhere,” Noll said.

In the meantime, the Davenport Fire Department’s Hazmat team put up booms to prevent the substance from spreading further into the river, Noll said. Cleanup will begin Monday.

— Thomas Geyer