Canadian recreational water quality guidelines - Indicators of fecal contamination: Applying the guidelines

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Guidelines for primary contact recreation

Guidelines for the fecal indicator bacteria Escherichia coli (E. coli) and enterococci have been developed for recreational areas used for primary contact activities (see Table 1 and Table 2). These values consider both the potential health risks and the benefits of recreational water use in terms of physical activity and enjoyment and are considered to represent an acceptable level of risk for recreational activities (see Rationale for primary contact guidelines).

Fecal indicator bacteria are used to indicate a potential increased risk to human health and are one component of a preventive risk management approach. Both culture-based methods (E. coli and enterococci) and polymerase chain reaction (PCR) based methods (enterococci) can be used for analysis. The choice of analytical method may depend on source water characteristics, the laboratory capacity and the necessity for same-day results. Further information on methods, including their advantages and limitations, can be found in the guideline technical document on Microbiological Sampling and Analysis (Health Canada, in publication). Further information on developing a sampling plan using fecal indicator bacteria can be found in the guideline technical document on Understanding and Managing Risks in Recreational Waters (Health Canada, 2023).

Table 1. Guideline valuesFootnote 1 Footnote 2 using culture-based methods
Indicator Beach Action Value (BAV)Footnote 4

E. coli

≤ 235 E. coli cfuFootnote 5/100 mL

Enterococci

  • marine and fresh water
≤ 70 enterococci cfuFootnote 5/100 mL
Footnote 1

Jurisdictions may develop alternative criteria for recreational areas that have very low risk of impacts from human fecal pathogens

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Footnote 2

Values from United States Environmental Protection Agency (U.S. EPA) (2012) for 36 illnesses/1000 primary contact recreators

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Footnote 3

E. coli can be adopted for marine waters if it is shown to adequately demonstrate the presence of fecal contamination

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Footnote 4

BAV concentrations are applied to each individual sample result (single or composite), rather than to averages or means

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Footnote 5

Methods with a most probable number (MPN) estimate are assumed equivalent to the cfu values given

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cfu
colony-forming units
Table 2. Guideline valuesFootnote 1 Footnote 2 using PCR-based methods
Indicator Beach Action Value (BAV)Footnote 3

Enterococci

  • marine and fresh water
< 1000 enterococci cce/100 mL
Footnote 1

Jurisdictions may develop alternative criteria for recreational areas that are very low risk for impacts from human fecal pathogens

Return to footnote 1 referrer

Footnote 2

Values from U.S. EPA (2012) for 36 illnesses/1000 primary contact recreators

Return to footnote 2 referrer

Footnote 3

BAV concentrations are applied to each individual sample result (single or composite), rather than to averages or means

Return to footnote 3 referrer

cce
calibrator cell equivalent

The epidemiological link between E. coli or enterococci concentrations and increased risk of adverse human health outcomes is based on an assessment of sites impacted to varying degrees by human sewage. Recreational areas that are not impacted by human or ruminant fecal sources, such as those only impacted by wildlife/birds, may contain fewer human pathogens. At these sites, higher levels of indicator bacteria may be present before the risk of gastrointestinal illness (GI) exceeds the acceptable level of risk. Microbial source tracking methods, along with EHSS, can be used to determine the probable source(s) of fecal contamination to help characterize the potential associated human health risks (see Box 1 and Health Canada, 2023). Recreational waters that have a very low risk of human or ruminant fecal contamination may benefit from the development of alternative criteria on a site-specific basis.

Application of the guidelines

Monitoring for E. coli or enterococci can provide a benchmark for public health decisions and provide valuable information on water quality changes that may be occurring at the beach. The guideline values recommended in this document are beach action values (BAV) for both culture-based (E. coli and enterococci) and PCR-based (enterococci) monitoring methods. Jurisdictions may choose to implement culture-based methods, PCR-based methods or both (for example, during side-by side testing of method performance), depending on their recreational water quality monitoring plan. Quantitative and digital PCR-based methods have the advantage of providing same-day results for decision making purposes, when water quality samples are collected and received by the laboratory in a timely fashion. Further information on the advantages and limitations of monitoring methods is included in guideline technical document on Microbiological Sampling and Analysis (Health Canada, in publication). Decisions regarding the frequency of monitoring, the number of samples to be collected, the areas to be monitored, the choice of indicators and the monitoring program design will be made by the appropriate regulatory and management authorities. Further guidance on these topics can be found in the guideline technical document on Understanding and Managing Risks in Recreational Waters (Health Canada, 2023).

The BAVs in this document are based on the water quality distributions observed in epidemiological studies and calculated by the United States Environmental Protection Agency (U.S. EPA) (see section 6.5, Appendix B, and U.S. EPA, 2012). These are recommended for informing day-to-day beach management decisions; however, they should not be the sole measure used for determining the acceptability of an area for recreational activities. EHSS data should also be considered by the responsible authorities and used as part of a preventive risk management approach to protect the health of recreational water users (see Health Canada, 2023). Public health decisions should balance the potential of increased health risks with the enjoyment and exercise that is associated with these activities.

If E. coli or enterococci concentrations exceed the established BAVs, this should trigger further actions by the responsible authorities. The actions required will depend on site-specific considerations, such as the sources of fecal contamination and the extent of the exceedance. Actions may include issuing a swimming advisory, immediate resampling of the site(s), and conducting a shortened EHSS. Further information on EHSS can be found in Health Canada (2023). A swimming advisory may be particularly warranted if the area is prone to impacts from human sewage (and therefore likely enteric pathogens), the beach is poorly characterized and therefore the source of the fecal indicator bacteria is unknown, or there is evidence of illness in the community suspected to be associated with the recreational area. It should be noted that other approaches, such as using predictive beach water quality models, may also be used to trigger beach management actions (Health Canada, 2023).

At beaches where the fecal sources impacting the water quality are unknown, beach managers may use various methods to test for human and ruminant fecal sources (see Box 1). In recreational waters where the fecal indicator bacteria levels exceed current guideline values, but the fecal sources are not human or ruminant, the appropriate regulatory authority can assess whether developing alternative criteria may be beneficial for informing and supporting beach management decisions at these sites. Alternative criteria could include modified guideline values for the current indicator bacteria or the inclusion of alternative or supplementary indicators. Guidance on developing alternative recreational water quality criteria is beyond the scope of this document. However, an overview of the types of information and site considerations needed prior to developing alternative criteria has been published elsewhere (U.S. EPA, 2014).

In addition to public health decisions, fecal indicator monitoring data can help determine a location's overall suitability for recreation. Summarizing fecal indicator data using geometric means is recommended for looking at water quality trends and for comparison to the geometric mean associated with the water quality distribution used to calculate the BAVs. Further information on using geometric mean concentrations is included in Rationale for primary contact guidelines.

Box 1

An approach to determining the source(s) of fecal material in fresh and marine waters used for primary or secondary contact recreation

Multiple lines of evidence should be used to identify the fecal source(s) impacting recreational waters. Much can be learned from EHSS and from expanding E. coli or enterococci surveillance in the immediate area around a beach or recreational water location. 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.

These techniques have been used to identify sources of fecal inputs at beaches across Canada. For example, multiple lines of evidence were used to identify the cause of frequent beach postings at Bluffers Park Beach in Toronto, Ontario (Edge et al., 2018). Beach observations, expanded E. coli surveillance, and microbial source tracking results consistently indicated the importance of reducing local impacts from bird fecal droppings and runoff from a parking lot and marsh inland of the beach. A bird management program and a berm engineered to reduce parking lot and marsh runoff led to immediate water quality improvements. The beach was subsequently awarded a Blue Flag certification. Similarly, studies in Alberta (Beaudry, 2019) and Ontario (Staley et al., 2018) applied advances in microbial source tracking (quantitative and digital PCR techniques) to identify sewage cross-connections into stormwater systems and bird excreta as the important fecal sources in some recreational waters.

It is important to recognize, however, that the predominant source of fecal matter may not be the most important source of human-infectious pathogens. Hence, if birds are the predominant fecal source, it is still critical to ensure that there is no human or ruminant fecal contamination. This is key because of the higher likelihood that these latter two sources may contribute the majority of human-infectious pathogens even when they contribute as little as 15% to 20% of the fecal load (Schoen et al., 2011; Soller et al., 2015).

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