Two men jump into Lake Michigan at a Chicago beach.
Jump in—the water's fine. Nam Y. Huh/AP

Chicago is the only major U.S. city to use a new method to test for bacteria at most of its beaches—and then issue same-day swimming advisories.

Millions of people in the U.S. get sick every year (often with a gastrointestinal illness) after swimming, boating, or fishing at a beach. Not that cities and states with beaches don’t try to prevent this. Authorities measure fecal bacteria—from sewage, birds, or other animals—in the water as an indicator of what other illness-causing organisms might have been released with the waste. If the levels are too high, they post a warning.

Under the usual method, labs grow bacteria from water samples, a process that takes about 24 hours to show results. So by the time high pathogen levels are evident and a beach warning goes out, “Mom is picking up the baby, washing sand out of their pants, and getting into the car,” said John Griffith, a principal scientist with the Southern California Coastal Water Research Project.

Three years ago, Chicago became the first large U.S. city to issue same-day water-quality warnings for its beaches. More than 200 of the yellow “risky swim” flags the city planted across its beaches last summer were there thanks to water analyzed that day.

A sign on the beach at Sunapee State Park in New Hampshire warns people to stay out of the water in 2014. Most beach authorities in the U.S. use a testing protocol that takes at least 24 hours to show results. (Jim Cole/AP)

For the sake of public health (and good PR), other local jurisdictions and states across the country have considered switching to the day-of testing protocol—but it’s easier said than done. So far, Chicago is the only major city to use a new method for the majority of its beaches, a choice facilitated by political will, capable labs, urban density, and some good fortune.

Chicago’s first stroke of luck came in 2010, when the Obama administration launched the Great Lakes Restoration Initiative. The city had been investigating better ways to monitor beaches for a few years already, says Cathy Breitenbach, the director of cultural and natural resources at the Chicago Park District: “We had the same frustrations that most beach managers had with the culture-based method that was available at the time.”

The initiative funds enabled Breitenbach’s department to keep experimenting at a time when prompt warnings about water quality were particularly important for the city. That year, Illinois was ranked 28th out of 30 states for beach water quality by the Natural Resources Defense Council. Two years later, the U.S. EPA debuted its approved, same-day water-quality assessment method, which provided a sort of supply list and manual for departments wanting to use this on their own beaches.

This method required new expertise and equipment. At the time, “there probably weren’t any [commercial] labs that could do seven-day-a-week testing and turn results around,” said environmental scientist Sam Dorevitch, who had already been studying this kind of beach testing and leads one such well-suited lab at the University of Illinois at Chicago. If the Park District, which had contracted out the old-school water assessment method to a nearby lab, wanted to adopt the protocol, it needed to hire a new facility. And what do you know—Dorevitch’s lab was there. “I suppose that’s sort of happy luck on our part,” acknowledged Breitenbach.

After trials in 2015 and 2016 to see how the same-day technique compared to the traditional method, the district went all in. The department pays Dorevitch’s lab about $300,000 a year to sample, analyze, and report results from water collected at 20 different lakefront locations every day from Memorial Day weekend through Labor Day.

Lab members leave around 5 a.m. in three groups, each on a different route to take two samples at their designated locations and return by 8 a.m., says Dorevitch. By 12:30 p.m., the test—a DNA analysis of how much bacteria is in the water—is done.

Consolidating all beach monitoring into a single lab simplifies switching to this more complicated, time-sensitive method. A same-day protocol is only beneficial if samples get from the beach to a lab fast enough for a notice to go up in the morning, says Julie Kinzelman, one of the research scientists who helped validate this technique for beaches. She helped make Racine, Wisconsin, the first city in the U.S. to earn EPA approval for same-day analysis in 2012, and that was partially possible because her lab is within two miles of both of Racine’s beaches.

Chicago is also fortunate in its geography. “Because we’re in a dense urban community, it doesn’t take that long to get to everything and get over to the lab,” said Breitenbach.

In Michigan, pivoting to same-day analysis is a statewide effort. Since the state has 1,222 beaches, coordinating which lab tests which beach takes more work. “It’s been a complicated five years,” said Shannon Briggs, the toxicologist and beach-monitoring coordinator for the Michigan Water Resources Division of Environment, Great Lakes, and Energy.

This summer will be the first time that Michigan health departments can post notices from same-day results. One of Briggs’s responsibilities during these years of preparation has been ensuring each region that wanted rapid analysis could be reached by an equipped and trained lab, whether the lab is federal, county-owned, or university-based. Up to 14 labs will serve beaches for same-day results, and Briggs and her colleagues wrote lab guides so that those without a masters in biochemistry can run the sensitive tests.

They plan on having to train a new batch of testers each year, too. Some will move on because they are students, but “when we train people with this new method, there is such a need for it that they’re able to go get better jobs,” Briggs said.

Briggs also spent much of the past few years developing a same-day analysis that’s compatible with the bacteria Lake Michigan beaches traditionally study. There are two kinds of bacteria a beach service can analyze to estimate water safety: E. coli and enterococci. Only enterococci survives long enough in salty water for ocean beaches to test. It’s also the species the EPA produced its first rapid method for in 2012.

Traditionally, freshwater beaches test with E. coli, says Briggs. Her state chose to develop a new EPA-backed protocol—which it’s using this summer—that would let it stick with the indicator species it had been using for decades. Though it also has freshwater beaches, Chicago was fine breaking with tradition and taking on the EPA enterococci rapid method. The park district’s job is to focus on best results for the public, and it doesn’t have to be concerned about data continuity, says Breitenbach.

Michigan also wanted to adopt a same-day technique that would alert labs of high contamination levels as often as the old method does. In Chicago, the new tests don’t reach the beach-warning threshold as frequently as the old ones did. Dorevitch isn’t sure why this discrepancy exists. But seeing as the old, slower method is “not too much different than chance for predicting water quality” (given the time that elapses between test and result), less-frequent yet timely warnings can keep more people out of contaminated water.

Even at beaches that are already reliant on enterococci testing, switching to same-day has taken a long time. In San Diego and other parts of Southern California, a reputation for fairly clean shores made it hard in the beginning to convince local politicians that this new method was worth the hassle, says Griffith. His agency works to give water managers across California the most accurate monitoring tools, and Griffith has helped San Diego move toward same-day methods.

He suspects changed attitudes have to do with wanting to show the city is a good beach steward and tourism being the city’s third-largest industry. Even if closures are rare, it’s important for them to be accurate and timely at beaches with a lot of traffic. Griffith can imagine same-day analysis becoming a selling point that other cities would have to catch up and offer, too: “You can see being the first to do that and publicizing it could be seen as an advantage to help lure more tourist dollars.”

San Diego recently submitted the results of its trials to the EPA. If officials decide to take it on full-time for every beach, they’ll soon navigate the logistics of having sufficient labs and people for the job.

Though it’s encouraging to see beaches offer prompt water-quality warnings, Briggs notes that another exciting thing about same-day analysis is that it’s a form of DNA assessment. That means labs can examine the samples further to see if the bacteria came from humans, birds, or other animals, or even test for genetic information indicative of an algae bloom or swimmer’s itch—all for the sake of going back and keeping the problem from developing in the first place.

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