PREPARED BY: Environmental Health

DATE: 2026-11-12

The Windsor-Essex County Health Unit (WECHU) conducts beach water surveillance in accordance with the Recreational Water Protocol, 2019 and the Operational Approaches for Recreational Water Guideline, 2018. Seasonal monitoring includes surveillance of water and weather conditions, assessment of potential pollution sources, and weekly sampling for Escherichia coli (E. coli), an indicator of fecal contamination from sources such as wildlife, agricultural and stormwater runoff, and septic or sewage system overflows. Exposure to elevated concentrations can cause gastrointestinal illness, including stomach cramps, diarrhea, fever, and vomiting.

During the 2026 swimming season, the WECHU routinely monitored seven public beaches. Building on the successful 2025 pilot, the predictive modeling program was expanded from four beaches to all seven local beaches and East Park Beach on Pelee Island. By combining current environmental conditions with historical water-quality data, the model produced same-day risk estimates to support timely public health decisions. This report summarizes the 2026 routine monitoring and predictive modeling results and identifies priorities for 2027.

DISCUSSION

Beach water testing was conducted from May 27 to August 26, 2026, at seven public beaches. Samples were collected on Wednesdays and analyzed for E. coli, with results posted on Fridays to the WECHU Beach Water Testing webpage and Beach Hotline (ext. 1490). Water quality warnings are issued when E. coli levels are between 201 and 999 per 100 mL of water, and beach closures are issued for results exceeding 1,000 E. coli per 100 mL of water. During the 2026 season, the WECHU issued 31 warnings and three closures, compared with 25 warnings and five closures in 2025 (Table 1). Results varied by beach, with Lakeshore Lakeview Park W. Beach accounting for eight warnings and two closures in 2026.

Table 1 shows six more routine-sampling warnings in 2026 than in 2025. Lakeshore Lakeview Park W. Beach increased from two to eight warnings, accounting for the net increase across the seven beaches; changes at the other beaches offset one another. These counts describe year-to-year variation, not its cause. Rainfall, runoff and other environmental conditions can affect bacterial levels, but the available summary does not establish which factors caused the 2026 increase. Routine sampling, warnings and closures remain the core protective measures, while weekday predictive estimates provide additional information between laboratory results. 

In partnership with local municipalities, the WECHU expanded predictive modeling to all seven local beaches and East Park Beach on Pelee Island. Project charters defined roles and responsibilities, while training and equipment supported standardized data collection. On weekdays, excluding holidays, beach staff measured turbidity (water cloudiness) and water temperature and submitted the data through an online survey. Predictive modeling uses a mathematical equation combining current environmental measurements with historical beach data to estimate E. coli levels. The model used these measurements to generate daily low-, moderate-, or high-risk assessments, which were posted on the WECHU website and Beach Hotline. Any beach closed on the basis of routine sampling remained closed regardless of the model’s prediction.   These are predicted risk levels, not laboratory-confirmed results. In accordance with the WECHU’s predictive modeling guidance, results are displayed as “Beach Closed” during a routine-sampling closure and as “Not Applicable” when required data cannot be collected.

The WECHU evaluated the predictive modeling program using stakeholder surveys, website analytics, and statistical validation (comparison of model estimates with measured water quality results). Municipal partners reported high satisfaction with the training, tools, and submission process and identified the model as a valuable source of timely water quality information. Staffing limitations, variable beach conditions, and occasional missed data submissions were reported but had minimal impact on implementation. Public engagement also remained strong: the Beach Water Testing webpage received more than 31,000 visits and generated approximately 300,000 user interactions throughout the season, including actions such as scrolling and clicking on interactive elements to access additional content. 

The 2026 validation summary reports 92.4% optimal or moderate agreement between predicted and measured water quality results, with category values of 39% optimal, 53% moderate and 8% low agreement. Agreement describes how closely model estimates correspond to measured results; these validation labels are distinct from the low-, moderate- and high-risk categories communicated to the public. Performance was reported as comparable to 2025, supporting consideration of predictive modeling as a complementary component of the WECHU’s recreational water management program, subject to these validation limitations. Expansion to East Park Beach was particularly valuable because the WECHU does not conduct routine sampling there due to its remote location; at that site, predictive modeling provides the primary source of current beach water condition information for residents and visitors, rather than laboratory confirmation of water quality.

The WECHU’s Beach Water Testing webpage explains that results reflect conditions at the time of sampling and that water quality can change with weather conditions and lake levels. Even when a beach is open, the WECHU recommends avoiding swimming for at least 48 hours after heavy rainfall, when the water is cloudy, or when swimmers cannot see their feet in the water. Routine-sampling closures take precedence over model predictions. At East Park Beach, messaging made it clear that routine WECHU sampling is not conducted and that the available estimates do not confirm bacterial levels. These safeguards communicate uncertainty; they do not establish that legal liability has been eliminated.

The 2026 can support continued integration of predictive modeling into the WECHU's beach monitoring program. Priorities for 2027 are to: 

• Sustain municipal participation and consistent weekday data submission through ongoing collaboration, standardized data collection processes, and regular communication with municipal partners. 
• Increase public awareness and use of predictive water quality reporting by enhancing promotion through the WECHU website, social media, and other public communication channels. 
• Refine model performance through evaluation of environmental predictors and annual model recalibration (updating the model using additional water quality and environmental data) to strengthen the timeliness, accuracy, and effectiveness of public health communication and recreational water management. Proposed evaluation priorities include confirming the agreement-category definitions and reporting paired-sample counts, false-negative counts and rates, and beach-specific findings, with particular attention to the limitations of validation at East Park Beach.