As part of new final guidelines for “Understanding and Managing Risks in Recreational Waters”, Health Canada has published a guideline technical document for monitoring fecal contamination to reduce gastrointestinal infections.
The fecal contamination document is one of several multiple guideline technical documents that consider the various factors that could interfere with the safety of recreational waters from a human health perspective. These include microbiological sampling and analysis, cyanobacteria and their toxins, physical, aesthetic and chemical characteristics, and microbiological pathogens and other biological hazards, Health Canada states.
Recreational waters are any natural fresh, marine or estuarine bodies of water used for recreational purposes, including lakes, rivers and even stormwater ponds and artificial lakes filled with untreated natural waters, according to the new guidance document. Activities that could involve immersion and ingestion of water with fecal contamination include swimming, wading, windsurfing and waterskiing, as well as secondary contact activities like canoeing, boating or fishing.
Health Canada states that recreational waters may be impacted by fecal material containing enteric pathogens from numerous sources, including discharged sewage, treated wastewater effluent, stormwater runoff from agricultural or urban areas, industrial processes, wild or domesticated animals, and even fecal shedding by swimmers.
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E.coli and enterococci are recommended as primary indicators of possible fecal contamination and of potentially elevated gastrointestinal illness risk in recreational waters impacted by human enteric pathogens. Using culture-based methods, the freshwater guideline value for E. coli is ≤ 235 E. coli CFU (colony forming unit) per 100 ml. For enterococci the marine and freshwater value is ≤ 70 enterococci CFU per 100 ml. These are considered “beach action values” often used to determine the need for swimming advisories.
The guidance document suggests that once shed from a human or animal, survival of E. coli is dependent on factors such as temperature, exposure to sunlight, available nutrients, water conditions such as pH and salinity, and competition from, and predation by, other microorganisms. Beach sand, sediments and aquatic vegetation can also prolong survival.
A variety of options are available for addressing contamination, such as environmental health and safety surveys and microbial source tracking investigation methods, as well as alternative indicators, to determine the sources of contamination and the remediation priorities to improve the water quality for recreators.
“Techniques like smoke or dye cross-connection testing of wastewater infrastructure or microbial source tracking methods may assist in identifying likely fecal input sources or unsuspected sources of fecal inputs,” Health Canada’s guidance document states.
Illnesses from fecal contamination often include either vomiting, diarrhea with a fever or stomach ache, and nausea with a fever.