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Lake County Beaches

New in 2014: Predictive Modeling used to determine water quality at Lake County Public Beaches

Starting this recreation season, the Lake County General Health District will be using a mathematical system that uses environmental factors and observations recorded each morning to estimate the levels of E. coli at the beach each day.  The mathematical models have been developed from the data collected from the several years of monitoring and sampling that have been recorded for Lake County’s two public beaches:  Mentor Headlands State Park Beach and Lake Metroparks Fairport Harbor Lakefront Park Beach. The model determines the probability of whether the single standard (235 E. coli per 100 milliliters of sample) will be exceeded based on the conditions at the beach each day.   

For several years the Lake County General Health District has monitored the bacteriological water quality daily between Memorial Day and Labor Day. Water quality samples were collected daily and measurements and observations were also recorded at the time of sample collection. Samples were then analyzed for concentrations of E. coli bacteria and compared to the single sample standard. 
During that time, the E. coli results were being compared to the recorded conditions at the beach such as wave height, turbidity, rainfall, numbers of birds and several other recorded variables that can potentially affect the water quality for swimming.  Models were developed and utilized simultaneously to test and compare to the existing method based on yesterday’s sample results and were found to be much more accurate and reliable for determining an exceedance of the water quality standard.

This data has been used to develop a site specific predictive model for each beach that will be used daily to determine the probability that the water quality will exceed the standard. This daily prediction will be reported as a Nowcast each morning to the beach operators. The Health District will still collect water quality samples three times per week for E. coli analysis to validate each predictive model for accuracy and reliability. 

As always is recommended that bathers avoid the water for 24-48 hours after a heavy rain of ½ inch or more in a 24 hour period since the likelihood of poor water quality generally increases.

Fairport Harbor Beach Daily Water Quality Nowcast

Mentor Headlands Beach Daily Water Quality Nowcast


     



For more information on predictive modeling, visit the Ohio Nowcast website