The Iowa Department of Natural Resources is investigating a manure spill on Brushy Creek southwest of Carroll in central Iowa. The D-N-R says an approximately 15-mile long section of the creek has been affected by manure runoff. A preliminary investigation by the D-N-R revealed the manure likely came from small cattle feedlots. Although icy conditions have made it hard to determine how many fish have been killed, the D-N-R indicates all of the fish in the affected areas are dead. As of Tuesday afternoon, the D-N-R had narrowed the likely sources of the spill to fewer than 10 farms.