Snow and field runoff could close beaches
Heavy precipitation can contribute to formation of water-borne bacteria.
(As seen on WZZM TV 13) LANSING — Even after all the snow Michigan received this winter is gone and melted, it could still find a way to adversely impact summer vacations.
A new study by the Department of Environmental Health Sciences at the University of Michigan suggests that extreme precipitation is linked to the need for beach closures. Intense precipitation may cause runoff from farm fields and increase bacteria such as E. coli in the water, leading officials to close beaches.
The study focuses on 12 Great Lakes cities from May through September in 2000-2006: Detroit and Grand Rapids; Buffalo and Rochester in New York; Chicago and Rockford in Illinois; Cleveland and Toledo in Ohio; Erie, Pa.; Gary, Ind.; Milwaukee, Wis.; and Minneapolis.
During the period studied, beaches in eight of those cities were closed for 100 days.
A co-author of the study, Kathleen Bush, said the focus of the research was to “influence early warning systems for swimmers and other recreational waterway users.”
The study, “Extreme Precipitation and Beach Closures in the Great Lakes Region: Evaluating Risk among the Elderly,” appeared in the International Journal of Environmental Research and Public Health.
“It was done to help beach managers evaluate risk ahead of time,” said Bush, a research affiliate at Plymouth State University Center for the Environment in New Hampshire. “There are early warning systems in development that utilize weather forecasts for beach closures that can inform beach management.”
The study took into account gastrointestinal illness, affecting the esophagus, stomach, rectum and other digestion-related organs. It focused on people age 65 and older.
“There are two issues,” said Bush. “Beach managers need to be informed, as well as the swimmers and the public. If the beach is not closed, the swimmers must understand the risk.”
Bush said beach managers need to communicate what is known about water quality to the general public.
As for the implications of the research on the 2014 beach season, it’s hard to say at this point, according to Sonia Joseph Joshi, outreach coordinator at the Center of Excellence for Great Lakes and Human Health.
“Just given the amount of snow we have had, if it turns out to be a warmer spring, there could be implications of increased runoff,” said Joshi, who is based in Ann Arbor. “There is a chance for more runoff, but given how cold it’s been, it will probably take a lot longer for the ground to thaw.”
While the researchers observed no consistent trend involving beach closures and GI-related hospital admissions among older people, 40,000 patients were hospitalized in the 12 cities studied due to the illness during the time of the study.
“One interesting thing about beach water is that survival of bacteria is really dependent on temperature,” said Lauren Fry, a research fellow and hydrologist at the Great Lakes Environmental Research Lab in Ann Arbor. “Spring runoff may have a big impact, but won’t be at a temperature that will have increased pathogen survival — at least for E. coli.”
Joshi said testing for E. coli, one of the drivers of GI illness, is difficult because of variation in the water depending on when and where testing takes place. The center is working on methods to increase accuracy for water quality testing.
“The beach water program we are doing is a very intensive time series sampling,” Joshi said. “Every 15 minutes we are sampling the same location and analyzing for bacteria and seeing variation in what the bacteria concentration is. You might sample one area and quality is fine, but if you wait 10 minutes it could be very different.”
This can cause uncertainty for health officials safeguarding beach users against water-borne illnesses such as GI.
“There isn’t much more they can do right now unless there are rapid tests,” said Joshi. “Those are very site-specific and not available at every single beach. Given the funding issues and what not, they are doing their best.”
Joshi said the current system for water testing requires an 18- to 48-hour period afterward to get results. “Because of this lag, beaches are being closed on days that could be fine, and open when it’s bad.”
Fry said health officials are trying to eliminate sources. “Eliminate combined sewer overflow and reducing likelihood of E. coli coming off of farm fields. Unfortunately, the one thing health officials are doing is what they are stuck with.”
As a result of changing climate, water-borne disease outbreaks have become an increasing occurrence.
Major precipitation incidents, especially in the winter, can increase flooding and overflow sewer systems. The resulting runoff has the potential to increase the transport of bacterium, viruses and other disease-causing micro-organisms, according to the study.
“With runoff, you’re getting increased phosphorous and nutrients that could trigger pathogens or viruses in the water,” Joshi said. “But those are very difficult to test for. Another thing is the increased risk of algal blooms, which act like an algae but have the potential to release toxins which could result in a skin rash.”
Joshi said her center is focusing on the development of tools to predict beach water quality. These tools include monitoring pathogen movement from rivers to where they wash up on beaches, as well as a tool to predict harmful algal blooms.
Fry said many researchers are developing statistical predictive models using meteorological variables such as rain and wave size to determine E. coli outcomes. Her lab at GLERL is focusing on physical models.
“We are predicting wash-off of bacteria from watersheds and its impact on water quality,” said Fry. “During dry periods, E. coli builds up on the landscape from wildlife. Rain then washes into rivers and to the mouth (of the rivers) where it impacts beaches.”
Fry says GLERL is working on predicting when and where the E. coli will hit the beach.