The Saline Branch connects with the Salt Fork of the Vermilion River which flows through much of Champaign and Vermilion Counties in east-central Illinois. The 2002 fish kill was the result of boiler cleaning substances that were released into a sewage treatment facility. The facility was overwhelmed by the high concentrations of ammonia in the cleaning substances and an unknown amount of ammonia was discharged into a ditch that leads to the Saline Branch.
Ammonia is highly toxic to aquatic life. Approximately 100,000 fish and other forms of aquatic life were killed. In addition, endangered bats and a variety of migratory birds were harmed by the loss of the fish and benthic macroinvertebrates which are important food sources. Benthic macroinvertebrates are animals that live on the bottom of a lake or other body of water and are tiny, yet large enough to be seen without a microscope, and do not have a backbone.
All mussel glochidia being carried on these fish were lost. Glochidia the larva of freshwater mussels of the family Unionidae. These larva live as a temporary parasite in the gills or on other external parts of fishes. No fresh dead adult mussels were discovered. The Salt Fork is the most western part of the range for the federally listed endangered clubshell (Pleurobema clava).