As beaches officially open this weekend, health officials are using cutting-edge computer systems, frequent water testing and even specially trained dogs to monitor water quality and keep Lake Michigan safe for swimming.
Communities across the country traditionally have relied on testing water samples to determine if there are dangerous levels of bacteria. The tests can take up to 24 hours to process, however, forcing officials to decide whether to ban swimming based on day-old data.
But new technology is beginning to slash that lag time, allowing health officials to analyze results more quickly and accurately.
In Lake County, water quality at three of the 12 Lake Michigan beaches overseen by the county's Health Department is evaluated every day by the computer-based SwimCast system, which analyzes real-time environmental factors so officials can make quick decisions about whether to allow swimming.
"It's certainly better than relying on data that's 24 hours old," said Mike Adam, senior biologist at the Health Department. Follow-up tests using traditional methods have shown that SwimCast is accurate 80 to 90 percent of the time, Adam said.
The water at all 12 beaches also is tested using traditional methods four times a week, he said.
The Chicago Park District, which oversees 24 beaches in the city, is working with Lake County to develop its own version of SwimCast, said Cathy Breitenbach, the district's director of lakefront operations. The district will collect environmental data this summer to prepare a launch of the system possibly next year, Breitenbach said.
As systems such as SwimCast are refined and expanded, tests of water samples remain the primary method for determining water quality. Chicago's beaches are tested each weekday and on weekends if high bacteria levels are detected late in the week, Breitenbach said. The beaches also are groomed each day, killing bacteria in the sand by exposing it to sunlight.
The tests measure levels of E. coli. Although E. coli usually isn't harmful, high levels of the bacteria are considered an indicator of other pathogens that can make people ill. The pathogens enter the lake in various ways, including from wildlife waste and storm runoff after heavy rains.
Swimming was banned at eight of Chicago's beaches Friday, the first day of the city's beach season. Another seven beaches were under a swim advisory, meaning swimming is permitted but people should exercise caution, especially children, the elderly and anyone with a compromised immune system.
Chicago instituted 41 swim bans last year, down from 58 in 2009, according to the Park District. The South Shore and 31st Street beaches each had six bans in 2010, more than any other city beaches.
Lake County had 111 swim bans last year, a slight decrease from 115 the year before, Adam said.
Adam and Breitenbach said waste from gulls is among the most common sources of pathogens along the lakefront. Gulls are the primary culprit at North Point Marina Beach in Winthrop Harbor, which led all Lake County beaches last year with 39 swim bans, Adam said.
Chicago's 63rd Street Beach also is plagued by the birds, Breitenbach said. That's why the Park District again is using trained border collies at 63rd Street and some other beaches to disrupt the birds when they try to land, forcing them to move to other locations.
Beach-goers can help keep areas clean by putting trash in garbage cans and not feeding gulls and other birds, Breitenbach said.
"People can really help make a difference to keep their own beach open for swimming," she said.
Twitter @RyanTHaggertyCopyright © 2015, The Baltimore Sun