Rapid bacteria testing at 63rd Street Beach keeps bathers out of troubled water

When a red flag is flying, the color should stop beachgoers from testing out the water along Chicago’s shores. A green flag means ‘go.’ In reality, however, the flag color is based on bacteria tests performed yesterday and today’s water safety is still a mystery.

But now the guessing game is over, at least at Chicago’s 63rd Street Beach. This summer marks the beginning of a pilot program designed to better judge whether the water is safe for swimming.

The program, implemented by Chicago Park District with help from the Illinois Department of Public Health, will use a technique known as predictive modeling. This method relies on data to provide a real-time report on current water conditions.

“This model looks towards the advent of having a preventive model in place that protects the public before any danger occurs, said Dr. Damon Arnold, director of the IDPH, at a press conference on Friday. “It is a step forward in the future.”

All of Chicago’s beaches are monitored daily by the Chicago Park District. Traditionally, water samples are collected from each beach and then returned to a lab. The culture-based methods currently being used, much like the strep throat tests of yore, take 18 to 24 hours to deliver results.

The problem? The water could have contained unsafe levels of E. coli bacteria yesterday, but wasn’t closed until today. The usage of predictive modeling, like the system that will be installed on 63rd Street Beach, and other rapid tests make the chances of knowing exactly what you’re swimming in much greater.

E. coli is one of the hazards of swimming in the Great Lakes, or in any body of water. Though it comes from different sources and finds its way into the water in various ways, all E. coli has one crucial commonality.

“When E. coli is found somewhere, there’s poop involved,” said Dr. Russell Robertson, chair of family medicine at Northwestern University's Feinberg School of Medicine. “No matter what, it’s the byproduct of the production of solid waste.”

The waste in question is sometimes from wildlife—seagull infestations have been linked to particularly high E. coli levels—and sometimes from humans. Perhaps most commonly, at least in Chicago, the bacteria gets into Lake Michigan after rain or waves wash it off the streets and beaches.

Some level of bacteria in water is perhaps inevitable, as it’s impossible to control everything going into a body of water as large as Lake Michigan. The amount of bacteria, however, dictates whether the water is safe for swimming.

Predictive modeling, already being used in several counties in the Great Lakes region, relies on factors such as wave height, sunlight, water flow and rainfall to determine the likelihood that water will be unsafe during a given hour.

Richard Whitman, field station supervisor at the Lake Michigan Ecological Research Station, spends his time working on predictive models, and has found them to be more reliable than culture-based methods.

“Just like we can predict rainfall for Chicago, we can predict whether or not we’re going to have a good beach day,” he said.

The predictive modeling method now in use at 63rd Street Beach, dubbed ‘SwimCast’, was adopted in Lake County in 2005.

Now, three of Lake County’s beaches have their own sensory systems. Located on pilings away from the shore, the systems collect data about wave height, the amount of sunlight, air and water temperature and rainfall every minute. Once an hour, the data is downloaded and sent to an on-shore computer system for the Health Department to analyze.

“It definitely, definitely is more effective than the culture, just because we’re making a more accurate and timely prediction,” said Mike Adam, senior biologist at the Lake County Health Department.

In addition to using more accurate testing to determine E. coli levels, the Chicago Park District is determined to attack the source of the problem as well. Solutions aren’t necessarily so easy, as all beaches are different and can have different sources of E. coli.

Holly Wirick, EPA Region 5 beach program coordinator, stresses the importance not only of monitoring but taking regular beach surveys.

“Knowing your beach is really important because you know what the sources are and can start taking means to reduce the pollution,” she said.

In Chicago, seagull droppings have been known to contribute to the problem, so steps have been taken to discourage the city’s gull population from settling on the beaches.

Border collies, accompanied by handlers, have begun patrolling two beaches with heavy gull populations and scaring the gulls away. Additional measures have also gone into effect to reduce the trash on beaches, such as new trashcans that keep wildlife from getting to food waste.

Because each beach is unique, predictive modeling may not be right for every Chicago beach.

Ellen Sargent, the Chicago Park District’s deputy director of natural resources and greening initiatives said that the park district has hopes to expand the program after it has proven successful at 63rd Street Beach.