Learn About Waterborne Pathogens

E. coli is found in the digestive tract of all warm-blooded animals, including humans.

Waterborne pathogens are bacteria, viruses, and parasites in the water that can make people sick. Recreational activities such as swimming, bathing, surfing, tubing, water skiing, paddle boarding, and water play increase the risk of exposure through ingestion, immersion, and body contact with the water. The most common symptoms of exposure include:

  • Diarrhea
  • Vomiting
  • Nausea
  • Abdominal pain (cramping)
  • Fever
  • Rash

Recreational water illnesses can be caused by bacteria such as shigella and E. coli, viruses such as norovirus, and parasites such as cryptosporidium and giardia. Symptoms may appear immediately, but some may occur one to two weeks after exposure.

Sources of Waterborne Pathogens

Fecal wastes are responsible for most of the waterborne pathogens found in recreational waters. These wastes can enter surface waters from a number of sources, including:

  • People who swim when they are sick with diarrhea and/or vomiting
  • Waste from dogs, livestock, waterfowl, and wildlife
  • Sewage spills or leaky septic tanks
  • Stormwater runoff following heavy rainstorms
  • Agricultural runoff from fields treated with manure
  • Waste discharges from boats

Waterborne pathogens can be deposited directly into the water from human and animal waste or washed into lakes and rivers when water comes in contact with fecal contamination.

Fecal Indicator Bacteria (FIB)

Indicator species such as Escherichia coli (E. coli) are often used to detect and quantify levels of fecal contamination in recreational waters. Although most strains of FIB don’t cause disease, they are good indicators of fecal contamination and can show the potential presence of the fecal pathogens capable of causing gastrointestinal illnesses.

While the available science on direct, rapid, and reliable detection of specific pathogens in recreational waters is progressing quickly, these new methods are not ready for full implementation at the national or state levels. The Division of Water Quality (DWQ) currently uses E. coli cultured-based methods in its monitoring and sampling program but will continue to investigate the use of other diagnostic tools such as microbial source tracking and molecular techniques as these technologies are refined.

Advisory Guidance

In 2020, DWQ restructured its E. coli Advisory Program based on recommendations from EPA and the Utah Department of Health. The new Waterborne Pathogen Advisory Program is working on updated guidance, thresholds, and objectives that focus on the health impacts of fecal contamination and align with the Environmental Protection Agency (EPA) 2012 Recreational Water Quality Criteria (RWQC).

Utah’s previous fecal contamination advisory program, the E. coli Advisory Program, uses E. coli advisory thresholds from EPA’s 1986 Recreational Water Quality Criteria (RWQC) recommendations. These recommendations used the Most Probable Number (MPN) method to estimate the concentration of E. coli in a water sample. Utah’s current recreational health advisory threshold is 409 MPN per 100 milliliters (mL).