Beach Water Quality Forecasting in the Great Lakes: Using Ocean Observing Systems to Predict Public Health Issues

The best current methods for assessing recreational water quality are based on nowcast models using E. coli concentration, a measurement involving incubation over at least 18 hours. The nowcast models reduce occurrences where people unintentionally swim in contaminated water as well as lost revenues from unnecessary restrictions of swimming. Contamination by bacteria, viruses and protozoa in recreational waters is a health risk and having timely accurate forecasts of water quality is critical to protect human health against adverse exposure situations. The Center of Excellence Great Lakes and Human Health is developing and testing new models incorporating 48-hour forecasts into beach nowcast models. Recent developments in operational Ocean Observing Systems in the Great Lakes allow forecastable parameters such as rainfall, wind direction, wind velocity and lake currents to be used as explanatory variables in nowcast models for beach water E. coli concentrations. The forecast models estimate the future risk of exposure to water-borne pathogens and provide swimming safety probabilities at modeled beaches. This service will be relevant because the swimming public can plan where to recreate several days in advance.