Bacteria counts were so high in Woods Creek Lake at Indian Trail Beach in Lake in the Hills last year that swimming was banned for eight days.
That's despite test results that show the beach should have been closed for 10 days.
Due to a lag in the time it takes the state to test water samples, beachgoers may be frolicking in filth. Illinois Department of Public Health officials said it can take as much as two days for test results on water samples with dangerously high bacteria levels to be discovered.
"That's one of the flaws in the system," said Melaney Arnold, IDPH spokeswoman.
According to IDPH records, water samples from 150 lake beaches in Cook, Kane, Lake and McHenry counties tested above the closure threshold 253 times in 2012. In most cases, those beaches were open during times when the bacteria levels would have mandated closure. There are no swimming beaches in DuPage County requiring the state to test.
Additionally, since water at most inland lake beaches is tested only twice a month, swimmers may spend days in contaminated water and never know it. Water at Lake Michigan beaches is tested with greater frequency, which partially accounts for a higher rate of contamination, health officials explained.
"We're following state code, but it mirrors a long-standing federal standard," said Justin DeWitt, chief of general engineering at the state health agency. "The test we're running isn't something we can do at the beach. It's more complex than a pregnancy stick."
The testing process requires incubation of water samples from lakes and rivers. The state agency tests for the potentially deadly E. coli bacteria at 439 beaches -- public and private -- throughout the state from just before Memorial Day through Labor Day. Results that indicate more than 235 "colony-forming units" per 100 milliliters require the closure of the beach, but that's often at least 24 hours after the sample has been collected.
"Those levels suggest eight to 10 people out of 1,000 might get ill," DeWitt said. "It survives in water very well."
E. coli is spread by ingesting infected fecal matter, usually from water fowl like geese, ducks and seagulls, but the bacteria can also come from the waste of humans and other warm-blooded animals. It can cause diarrhea and other symptoms, some severe.
When tests come back with results above the 235-colony threshold, samples will be collected daily and the beach will be closed until bacteria levels drop, DeWitt said.
Beachgoers are warned to "swim at their own risk" if test results show bacteria levels are between 126 colonies and 234 colonies, health officials said. The tests max out at 2,419 colonies.
Samples from Indian Trail Beach maxed out three times in 2012, records show. The beach was closed all three of those days. In all, the 150 beaches maxed out the tests 27 times last year.
"A lot has to do with site-specific conditions," said Mike Adam, a senior biologist at the Lake County Health Department. "It can be stagnation of water, and another big thing is the presence of water fowl."
Just 300 yards from Indian Trail Beach is Woods Creek Lake's other lakefront recreation spot, Butch Hagele Beach. By comparison, samples from the lake at Butch Hagele never tested above the 235-colony threshold in 2012, according to IDPH records. Additionally, over a four-year span, water samples from Butch Hagele tested above the closure level only twice, while samples from Indian Trail Beach from 2008 to 2012 exceeded those standards 32 times.
"There's a different current, and it's just the way the land is at the two beaches," said Trudy Wakeman, Lake in the Hills' director of parks and recreation, the agency that oversees operations at the beaches.
Weather also plays a significant role in the health of beach water.
Officials recommend staying out of lake water for 24 hours after a heavy rain.
"That's because of runoff," said Debra Quackenbush, a spokeswoman for the McHenry County Health Department. "Some of it can be animal waste washing off the roads into the lake or agricultural runoff. We don't treat beaches with anything. Nature takes care of itself."
The county health department is responsible for taking samples from Woods Creek Lake and reporting the results to the state agency. That provides a quicker turnaround than having state workers do it themselves, but it's still more than 24 hours.
Wakeman said her department warns swimmers when staff members believe conditions have created potentially higher bacteria levels, but they don't have test results to prove it.
"I'd say it's about 50/50 when people see a yellow flag that it will keep them out of the lake," she said. "People that are used to lakes and water will probably go in more often."
Other agencies are proactive as well. Lake County uses a system called SwimCast at four popular beaches along Lake Michigan to measure conditions like air and water temperature, humidity, wave height, sunlight and "other water quality parameters" to predict whether bacteria levels would be high enough to warrant closure or warnings, Adam said.
Adam said the department also relies on the public.
"If something doesn't look right or smell right, let us know," he said.