In March 2002 an unpermitted release of partially treated sewage caused a fish kill in the lower reach of Hecker Creek and a portion of the Yellow River at its confluence with Hecker Creek, in Allamakee County, Iowa. The sewage had built up in the nearby municipal sewage treatment lagoons from industrial clients. It contained high ammonia concentrations and created biological oxygen demand conditions that were toxic to aquatic life. Approximately 3.1 miles of stream length were affected by the kill. A total of 4,860 fish were found dead including 4467 minnows, 276 darters, 106 suckers, and 11 stonecats.
The fish resources in the Yellow River are used for recreational fishing and serve as food for resident wildlife and migratory birds. It was expected that over time, aquatic life would re-colonize the affected reaches of these streams and fish species, numbers, and age structures would recover to the pre-spill condition. Therefore, the intent of the restoration action was to compensate for the interim lost use of the natural resources injured by the fish kill.