What causes swim advisories and swim bans?
Swim advisories and swim bans are issued for potentially hazardous weather or water quality conditions. The Chicago Park District follows United States Environmental Protection Agency (USEPA) guidance for testing of recreational waters and tests for indicator bacteria called Escherichia coli (E. coli) in the collected samples. There are many unknown sources that cause high levels of E. coli: high temperatures, weather events, storm water, sand, low lake levels and animal waste. Studies have suggested a link between fecal droppings from ring-billed gulls and other birds, which is why feeding birds at the beach is discouraged and harassment techniques have been implemented at some sites that have a history of high levels of E. coli. The Park District provides numerous lidded containers for trash and recyclable materials to decrease the available food source for these “nuisance species”. Additionally, the Chicago Park District Department of Natural Resources cleans each beach daily.
