07/20/2011 01:43 pm ET Updated Sep 19, 2011

Rainbow Beach Swim Ban: Closed Due To Poor Water Quality

When the "Testing the Waters 2011" report came out last month, saying that Illinois beaches were among the most contaminated in the country, we sort of shrugged our shoulders and figured there was nothing to do but keep on swimming.

Unfortunately for some Southeast Siders, that's not an option on Wednesday.

The Chicago Park District has closed Rainbow Beach at East 77th Street today because of poor water quality. The closure comes on a day when the heat was expected to approach record highs, as the city is in the grips of a massive heat wave.

There's also a "swim advisory" at the South Shore Beach based on water quality, which means that there "may be an increased risk of illness based on current monitoring for E.coli bacteria," according to the Park District.

Wednesday's closure come just a day after bizarre weather shut down most of the city's beaches. Thick, rolling fog obscured visibility for lifeguards, leading to a swim ban at every beach except the 12th Street Beach on Tuesday.