Science-Based Tools Can Help Prevent Illness at Ohio and New York Beaches

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These interactive, mobile-friendly websites use maps of beach locations to indicate whether or not estimated bacteria levels exceed state safety standards. 

New and updated daily water-quality advisories called nowcasts show whether bacteria levels in swimming areas at selected Lake Erie and Lake Ontario beaches are suitable for recreation.

This season, the Ohio Nowcast has a new look and format, and the New York Nowcast is easier to use than ever. Developed by the U.S. Geological Survey and partners, these interactive, mobile-friendly websites use maps of beach locations to indicate whether or not estimated bacteria levels exceed state safety standards. Rapid nowcast information is available for eight beaches and one river in Ohio and for 11 beaches in New York. 

“Nowcasts are similar to forecasts except they estimate current instead of future conditions,” said Amie Brady, a USGS hydrologist and coauthor of a recent nowcast study. “We estimate current bacteria levels using models that are calibrated for each beach, taking into account existing weather and environmental conditions.”

Older methods to determine levels of harmful bacteria, such as Escherichia coli (E. coli), take at least 18 hours to complete. During this period, E. coli levels may increase or decrease substantially depending on rainfall, light levels and other factors. As a result, beaches may be posted with incorrect advisories based on E. coli levels from the previous day. Nowcasts provide near real-time predictions for more accurate bacteria advisories.

“The new Ohio Nowcast is more interactive and easier to use than the old format because users can now click a beach on a map and obtain its water-quality information using their computer or mobile device,” said Brady. “The New York Nowcast has been offering this interactive format for several years, adding new beaches each year of its operation.”

Beach advisories or closings in the United States are issued when levels of bacterial indicators, such E. coli, exceed safety standards. E. coli is found in the intestines and feces of warm-blooded animals and can exist in sewage and waste. These indicators do not necessarily cause disease, but they signify the possible presence of disease-causing organisms. If the concentration of E. coli exceeds state standards, officials will advise visitors not to swim because of the risk of illness.

Scientists with the USGS and partners have been providing rapid predictions of bacteria levels at beaches through the Ohio Nowcast since 2006 and the New York Nowcast since 2012.

A full list of cooperators on the Ohio and New York Nowcasts is available in the USGS report.

For more information on water-quality research in Ohio and New York, please visit the USGS MI-OH Water Science Center and the USGS New York Water Science Center websites.