What causes high levels of indicator bacteria?
There are many unknown sources that can cause high levels of E. coli in the water. Studies have shown that potential sources include waste from gulls, pets and wildlife, high temperatures, severe weather, storm water runoff, bacteria from the sand, and low lake levels. Research has suggested a strong link between high E. coli levels and fecal droppings from ring-billed gulls and other birds, which is why feeding birds at the beach is prohibited and gull harassment techniques have been implemented at some sites that have a history of high levels of E. coli. The Park District also 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.
