Nowcast beach safety advisories topic of May 5 talk

May 4, 2011 | Events, UToday
By Meghan Cunningham

ohio-nowcastBefore you head to the Lake Erie beach at Maumee Bay State Park, check the Nowcast on

This summer, The University of Toledo and the U.S. Geological Survey (USGS) are initiating a system to quickly estimate bacteria levels and provide beach advisories to swimmers headed to Maumee Bay State Park in Oregon. This system already is used at two other beaches — Huntington Reservation (Bay Village) and Edgewater (Cleveland Lakefront State Park). By 9:30 each morning, the Nowcast is posted for the day, enabling swimmers to access advisory information before they leave for the beach.

“The Nowcast system is similar to a weather forecast except current conditions instead of future conditions are estimated,” said Donna Francy, USGS research hydrologist for the study. “Current bacteria levels are estimated using a computer model especially calibrated for each beach that takes into account current weather and environmental conditions.”

Learn more about Nowcast at a free, public seminar Thursday, May 5, at 7 p.m. at the Lake Erie Center, 6200 Bayshore Road in Oregon. Scheduled to speak are Dr. Kris Barnswell, UT research assistant professor of environmental sciences, Amie Brady of the U.S. Geological Survey, and Corey Schwab of the Ohio Department of Health.

Beach advisories or closings in the United States are issued when levels of bacterial indicators, including Escherichia coli (E. coli), exceed safety standards. E. coli is found in the intestines and feces of warm-blooded animals. Indicator organisms do not necessarily cause disease, but they are present in sewage and waste and indicate 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.

Unfortunately, current methods to determine levels of E. coli take at least 18 hours to complete. During this time, levels of E. coli may increase or decrease substantially, according to Francy. A heavy rainfall may cause an increase in E. coli levels overnight. A bright sunny day may cause E. coli levels to fall. So the beach erroneously may be posted with an advisory based on measured levels of E. coli from the previous day.

“We collected weather and environmental data for three years to develop mathematical models to predict E. coli concentrations at Maumee Bay State Park,” Francy said. “Instead of waiting 18 hours for E. coli to grow in the laboratory, we use quickly measured factors that explain changes in E. coli concentrations, enter them into a computer program, and obtain a Nowcast of recreational water quality in less than two hours.”

Researchers in Dr. Daryl Dwyer’s laboratory at UT’s Lake Erie Center have been working with Francy and others at the U.S. Geological Survey to initiate the Nowcast system for Maumee Bay State Park.

“By partnering with USGS, we discovered that wind direction and speed, turbidity (water clarity), solar radiation and lake level were the best factors to predict levels of E. coli,” said Dwyer, UT associate professor of environmental sciences. “The USGS has led the way in developing this predictive tool that can be used to protect the health of recreational beach users. Their work for the Edgewater and Huntington beaches in Cuyahoga County first demonstrated that each beach requires a unique combination of weather and environmental factors to predict bacteria levels for the Nowcast. We have demonstrated the systems usefulness here in Lucas County and, hopefully, this will be the impetus for its adoption at other beaches.”

“The models have done better than the old way of determining water quality conditions — using the previous day’s E. coli concentration. We know the Nowcast is a useful system and are working to improve predictions at Edgewater and Huntington,” Francy said. “We are also working to expand Nowcasting to other beaches in Ohio.”

The model predicts the probability of exceeding the Ohio single-sample maximum bathing-water standard for E. coli (235 colonies per 100 milliliters). How does this help the potential beachgoer decide whether to make the trip?

“These data obtained by UT and USGS researchers are used to predict water quality and a probability factor for an exceedance that are displayed at the Nowcast website. By viewing this website, the beachgoer can access this probability factor, but even more importantly, can access an advisory as to the water quality of the beach and if conditions are safe for swimming,” Dwyer said.

Further information on how to use Nowcast and how data are obtained and used for the predictive model can be obtained by contacting Pamela Struffolino at the Lake Erie Center at 419.530.8380 and Brady at the USGS Ohio Water Science Center in Columbus at 614.430.7760.

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