Unfortunately, modern living in the big city has its downsides, one of them being the inevitable polluting of Lake Michigan. The water along Chicago beaches can sometimes reach a bacteria level that may be unsafe for swimming. The Chicago Park District is continuously testing the water along the many beaches, and are specifically looking for high levels of E. coli bacteria. The park district has instituted a flag system along the shore to advise swimmers as to water conditions, and to let them make the personal decision if they want to swim or not. Here's a quick guide to the three-tier advisory system to help you stay safe:
- Green flags: Water safe, swimming permitted
- Yellow flags: Bacteria levels are above 235 colonies per milliliter of water -- increased risk of illness present
- Red flags: more than 1,000 bacteria colonies per milliliter of water present -- swimming ban is in effect
Take extra care when visiting the beach with small children or the elderly, or anyone else with weakened immune systems, as those people are at extra risk and probably should not swim even when levels are at "code yellow".
Our About.com Healthcare Center has more information about E. coli enteritis and its symptoms.
Fast Fact: A large part of the bacteria is the result of sea gulls drawn by garbage and goodies from beachgoers, so do your part and put all trash and uneaten food in the covered trash receptacles along the beach and do not feed the gulls.

