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Ohio Water Science Center

Nowcasting Beach Advisories at Ohio Lake Erie Beaches

U.S. Geological Survey Open-File Report 2007–1427

By Donna S. Francy and Robert A. Darner

In Cooperation With the Ohio Lake Erie Office, Northeast Ohio Regional Sewer District, Cuyahoga County Board of Health, and U.S. Environmental Protection Agency Region 5, Water Division


This report is available below as a 13-page PDF for viewing and printing.


Data were collected during the recreational season of 2007 to test and refine predictive models at three Lake Erie beaches. In addition to E. coli concentrations, field personnel collected or compiled data for environmental and water-quality variables expected to affect E. coli concentrations including turbidity, wave height, water temperature, lake level, rainfall, and antecedent dry days and wet days. At Huntington (Bay Village) and Edgewater (Cleveland) during 2007, the models provided correct responses 82.7 and 82.1 percent of the time; these percentages were greater than percentages obtained using the previous day’s E. coli concentrations (current method). In contrast, at Villa Angela during 2007, the model provided correct responses only 61.3 percent of the days monitored. The data from 2007 were added to existing datasets and the larger datasets were split into two (Huntington) or three (Edgewater) segments by date based on the occurrence of false negatives and positives (named “season 1, season 2, season 3”). Models were developed for dated segments and for combined datasets. At Huntington, the summed responses for separate best models for seasons 1 and 2 provided a greater percentage of correct responses (85.6 percent) than the one combined best model (83.1 percent). Similar results were found for Edgewater. Water resource managers will determine how to apply these models to the Internet-based “nowcast” system for issuing water-quality advisories during 2008.





Analytical Methods

Variables for Model Development

Testing and Development of Predictive Models


Performance of the Models in 2007

Exploratory Data Analysis

Model Development, Diagnosis, and Selection for 2008

Next Steps




1. Map showing location of study area.

2. Photo of wave-height measuring buoy in the nearshore area at Edgewater, Cleveland, Ohio.


1. Variables, model properties, and model responses as compared to using previous day's Escherichia coli (E. coli) concentrations in 2007.

2. False-negative and false-positive responses as a percentage of total exceedances and nonexceedances of the bathing-water standard,
    respectively, for different data segments, by date, for predictive models.

3. Pearson's r correlations between log10 Escherichia coli (E. coli) concentrations and explanatory variables at three Lake Erie beaches,

4. Examination of candidate Huntington 2000–2007 models.

5. Examination of candidate Edgewater models for 2004–7.


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Whole report (682 KB) - 13 pages (8.5" by 11" paper)

Suggested Citation:

Francy, D.S., and Darner, R.A., 2007, Nowcasting beach advisories at Ohio Lake Erie beaches: U.S. Geological Survey Open-File Report 2007–1427, 13 p.

For more information about USGS activities in Ohio, visit the USGS Ohio Water Science Center home page.

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Last modified: Wednesday, 07-Dec-2016 20:36:40 EST
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