An automatic shut off valve failed, allowing about 50 gallons to diesel fuel into the South Fork of the Iowa River near Iowa Falls.

The Fuel spilled while an Agvantage FS truck was filling a farm diesel tank about five miles south of Iowa Falls. Diesel fuel flowed about 50 feet into the river after an automatic shutoff valve failed.

The fuel had traveled about three miles downstream by 5 p.m. Monday. An environmental cleanup contractor was en route. Agvantage FS is working with the contractor to place booms and contain the spill before it reaches Highway 65.