Starting Thursday, March 27, 2025, the City of Bloomington will be treating parts of Lake Bloomington and Evergreen Lake to manage algal growth. This is in response to an increase in microcystin, a naturally occurring toxin that can form during algal blooms.
Unusual weather conditions this winter—lower water levels, little precipitation, and warmer-than-normal temperatures—led to an unexpected algal bloom in January. Since then, the City’s Water Department, in coordination with the Illinois Environmental Protection Agency (IEPA), has been closely monitoring water quality. Testing has confirmed that microcystin levels remain well below any level that would require a health advisory.
The City has already been using powdered activated carbon (PAC) as part of its ongoing water treatment process, and this algaecide application will further boost those efforts. The targeted treatment in portions of both lakes will help break down microcystin and reduce taste and odor compounds that sometimes affect drinking water.
Drinking water remains safe, meeting all state and federal quality standards, and recreational activities on the lakes will not be affected. The City will continue monitoring conditions to ensure high water quality. For questions or more information, contact the Water Department at 309-434-2225 or water@cityblm.org.
