Canadian recreational water quality guidelines - Indicators of fecal contamination: Development of updated guidelines

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Primary contact guideline values

Historical guideline values for fecal indicators

The previous Guidelines for Canadian Recreational Water Quality, published in 2012, recommended guideline values for the fecal indicators E. coli and enterococci. E. coli values were recommended primarily for freshwaters whereas enterococci values were primarily applied to marine waters. The guidelines noted that the values for E. coli could be applied in marine waters, and enterococci in fresh waters, if it was adequately demonstrated at a given site that they were associated with the presence of fecal contamination in these water matrices.

The guideline values comprised a geometric mean (GM) value and a single sample maximum (SSM) value for each indicator (Table B1). The geometric mean values were calculated based on a minimum of five samples, collected at times and sites as to provide representative information on the water quality likely to be encountered by users. If either guideline value was exceeded, the minimum action taken was immediate resampling. Only culture-based methods were included.

Table B1: Comparison of primary contact guideline values

2012 guidelines

Current guidelines



(cfu/100mL) (cfu/100mL) (cfu/100mL) (cce/100mL)Footnote *
E. coli 200 400 235 N/A
Enterococci 35 70 70 1000
Footnote *

using PCR-based methods

Return to footnote * referrer

The GM values were based on U.S. EPA's regression analysis of epidemiological data (Dufour, 1984; Cabelli, 1983) relating E. coli or enterococci concentrations to the incidence of swimming-associated gastrointestinal illness. The SSM values were set at a factor of 2 times the recommended geometric mean values. The resultant SSMs were consistent with the maximum allowable indicator densities reported in U.S. EPA (1986). Using the regression analysis, the E. coli and enterococci guideline values corresponded to seasonal gastrointestinal rates of approximately 10 to 20 HCGI per 1,000 swimmers.

Current guideline values for fecal indicators

The current guideline values, as presented in Table B1, continue to recommend the use of E. coli and enterococci as indicators of fecal contamination. E. coli continues to be used primarily for fresh waters. However, enterococci is now recommended for both fresh and marine waters. Similar to the 2012 guidelines, E. coli can be used for marine waters if it is adequately demonstrated that they are associated with the presence of fecal contamination in the marine environment.

The guideline values are comprised of beach action values (BAVs) for each indicator. The results from each individual (or composite) sample should be compared to the BAVs. An exceedance of a BAV should trigger further actions by the responsible authorities, such as resampling or issuing beach notifications. Both culture-based methods (E. coli and enterococci) and PCR-based methods (enterococci) can be used for analysis.

The BAVs are adopted from U.S. EPA (2012) and represent the 75th percentile value of the water quality distribution corresponding to a potential risk of 36 GI for every 1,000 people engaged in primary contact activities. As noted in the section Definition of gastrointestinal illness, based on a change in the definition of gastrointestinal illness used in the epidemiological studies, 36 GI is considered equivalent to 8 HCGI.

The current guidelines also acknowledge that the sources of fecal contamination are important for determining the potential risk to human health. Therefore, recreational waters that have a very low risk of human or ruminant fecal contamination may benefit from the development of alternative guideline values.

Rationale for the change in approach

Several significant changes have been included in the current fecal indicator guidelines. This includes moving away from using GM and SSM's to using BAVs for day-to-day beach management (based on data from the most recent epidemiological studies), recommending PCR-based monitoring methods in addition to culture-based methods and encouraging the use of MST and the development of alternative criteria (where appropriate).

In the 2012 Guidelines for Canadian Recreational Water Quality, dual limits (i.e., GM and SSMs) were included as each limit provided different information on water quality. The single-sample limit was intended to alert management to any immediate water quality issues, whereas the GM limit was intended to alert authorities to chronic contamination problems. A minimum of 5 samples were recommended for calculating the GM. However, the greater the number of samples included in the GM, the better the calculated value reflects the water quality. As many locations are sampled infrequently (for example, once a week), collecting enough samples to calculate a representative GM could take a significant portion of the swimming season. Therefore, although the GM is recommended for understanding longer-term water quality trends, and for determining an area's overall suitability for recreation (for example, does the water quality meet the GM associated with 36 GI cases/1,000 individuals engaged in primary contact activities), it is less useful for making day-to-day beach management decisions. Consequently, the BAV approach has been adopted. BAVs are similar to SSMs in that they alert management to any immediate water quality issues that need to be investigated.

The BAVs also reflect the most recent epidemiological studies conducted in the United States. Unlike earlier studies, the new epidemiological studies did not show a linear relationship between GI illnesses and increasing concentrations of E. coli and enterococci (detected using culture-based methods). They did determine that at a GM concentration of 30 or 35 enterococci per 100 mL, the risk between exposed and unexposed individuals was significantly different. E. coli data were not available for these studies. However, the E. coli values that represent a similar level of health risk were calculated and have been adopted for this guideline document. This harmonizes the risk levels associated with both fecal indicators. The BAVs are based on the 75th percentile of the water quality distribution associated with the GM concentrations calculated from the new studies. Using the 75th percentile (as opposed to the 90th or 95th percentile) is a more conservative approach as the 75th percentile value is a lower number, meaning beach actions are triggered when fewer fecal indicator organisms are present. This provides better protection of sensitive sub-populations such as children.

PCR-based methodologies for monitoring water quality are now included as the science of PCR-based monitoring is well-established and more accessible to responsible authorities. Access to PCR-based monitoring also makes MST research more accessible, as many MST methods use PCR-based technologies for determining the fecal sources impacting a water body. It is also well established that the level of human pathogens varies between fecal sources, with human and ruminant sources representing the greatest risk. As the methods for determining fecal impacts at a recreational area are more accessible, it is possible to better characterize the potential risk at a recreational site and allow for the development of alternative recreational water quality criteria (where appropriate). Any alternative values developed need to maintain the same level of public health protection (that is, no more than 36 GI illness /1,000 individuals engaged in primary contact activities).

Secondary contact guideline values

Historical guideline values

The Guidelines for Canadian Recreational Water Quality (published in 2012) provided advice for secondary water contact activities. It was recognized that these activities resulted in a lower degree of water exposure at most times. However, there was limited research available on the potential risks of acquiring illness during secondary contact activities so a precise health-based fecal indicator limit could not be derived. Instead, based on the available information, it was recommended that a factor of 5 be applied to the GM fecal indicator concentrations used to protect primary recreation users as a means to establish a fecal indicator limit for secondary contact activities.

Current guideline values

There is still insufficient epidemiological data to derive health-based fecal indicator limits for secondary contact recreation. However, there has been some additional research on the differences in exposures between primary and secondary contact activities. Research has shown that fewer individuals report swallowing water and individuals swallow a lower volume of water, compared to primary contact activities. This means exposure is lower. To establish a fecal indicator limit for secondary contact activities, a direct multiplier can be applied to the BAV based on the difference in ingestion volumes between primary and secondary contact activities. The multiplier is the decision of the responsible authority but it is suggested this value should be between 3 and 8, based on the studies available. The choice of multiplier should consider the sources of fecal contamination in the recreational areas.

Rationale for the change in approach

Since the publication of the 2012 Guidelines, additional research investigating the risks to human health through secondary contact recreation provides additional data on the difference in exposures between primary and secondary contact activities. It has also been established that recreational areas that are not impacted by human or ruminant feces, such as those only impacted by wildlife/birds, may contain fewer human pathogens, and could benefit from the development of alternative guideline values. Based on these two advancements, a single universal multiplier and a range of multipliers were considered. It was determined that a set multiplier, applied to all recreational areas, was too limited as it does not allow site-specific considerations. Instead, a range of potential multipliers is provided that can be used by responsible authorities to make decisions on secondary contact guideline limits that consider both the potential health risks (based on site-specific considerations) and the benefits of recreational water use in terms of physical activity and enjoyment.

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