The State of Ohio uses standards for E. coli to assess whether the water quality is acceptable for swimming or other recreational activities. E. coli is a bacterium that is not usually disease causing but is found in the gastrointestinal tract of healthy warm-blooded animals, including humans, and their feces. Its presence is an indicator that disease-causing organisms are also likely to be present. For Lake Erie beaches, if the level of E. coli goes over the single-sample bathing-water standard of 235 colony-forming units per 100 milliliters (CFU/100 mL), the beach manager will issue a water-quality advisory. For the stretch of the Cuyahoga river that includes the nowcast site at Jaite, the river has been designated as primary-contact recreation, and the single-sample primary-contact standard is 298 CFU/100 mL. A milliliter is a unit of volume in the metric system; 100 milliliters is equivalent to just under ½ cup.

What is commonly done to monitor recreational water quality is to collect a water sample from the swimming area or stream, transport the sample to a laboratory, and determine numbers of E. coli in the sample. The problem is that it takes at least 18 hours to grow E. coli in the laboratory. Unfortunately, by the time E. coli results are compiled, water-quality conditions may have already changed. By contrast, it takes less than an hour to estimate recreational water quality using the predictive model and transmit results through the nowcasting system.