ODEBOLT, Iowa (AP) — Iowa environmental officials are investigating a chemical fertilizer spill in western Iowa. The Iowa Department of Natural Resources say a tanker carrying ammonium thiosulfate, a liquid fertilizer, tipped over Friday morning in Odebolt.

Investigators say the tanker, which was bound for a bulk plant in Boone, was carrying about 4,340 gallons of fertilizer. Officials say it’s not known how much of the product leaked from the top fill port before it was stopped and contained.

Some of the fertilizer ran into a small tributary, through a culvert and flowed through town to Odebolt Creek. Officials have tested water quality at several places and found elevated levels of ammonia, but did not detect ammonia downstream. There are no fish in the tributary. Cleanup of the spill is planned.