A report issued Thursday by watchdog groups Environment Montana and Frontier Group says that Western Sugar Cooperative in Billings exceeded its permitted limit for release of materials including toxic pollutant ammonia nitrogen, E. coli and fecal coli-form into the Yellowstone River 56 times during a 21-month period.

E. coli is a bacteria that lives in human and animal intestines. Fecal coli-form is found in an aquatic environment and indicates the water has been contaminated with fecal material from humans or animals.

The report, “Troubled Waters,” details over eight thousand instances nationwide of pollutants released into waterways in violation of Clean Water Act permits.