Chicago’s beach season barely got its feet wet before the warning flags went up at 31st Street.
Margaret T. Burroughs (31st Street) Beach briefly raised a yellow swim-advisory flag during the opening week of the 2026 season after rapid water tests showed bacteria levels above the Chicago Park District’s action threshold. The advisory, which landed over Memorial Day weekend, rattled some early-season beachgoers and had environmental advocates warning it may be a preview of what is to come this summer. Lifeguards remained on duty and swimming was allowed, but with caution, while the yellow flag flew.
The Chicago Park District issued the advisory for the South Side beach on May 28 and lifted it the next day, according to Block Club Chicago. Block Club reported that the district’s rapid qPCR test found Enterococci above its advisory level, triggering the yellow warning.
According to the Chicago Park District, rapid water-quality results for city beaches are posted on its online dashboard at about 1:30 p.m. each day. A yellow swim advisory goes up when qPCR Enterococci measurements exceed 1,000 CCE. The district notes that lifeguards are scheduled from 11 a.m. to 7 p.m. during beach season and that flag colors can change throughout the day as conditions shift.
The Illinois Department of Public Health’s BeachGuard system lists Margaret T. Burroughs (31st St.) Beach as monitored by the Chicago Park District and currently open, even as the statewide dashboard still shows other Illinois beaches under active advisories. BeachGuard serves as the official database for swim closures and contamination advisories across the state.
Advocates Point to Infrastructure and Funding
Environmental advocates say the brief advisory is less of a fluke and more of a warning sign about old sewer and stormwater systems that can send polluted water into Lake Michigan. Emily Kowalski of Environment Illinois said “now is the time to fix our water infrastructure and stop the flow of pathogens to our beaches,” and urged U.S. House members including Reps. Mike Quigley and Lauren Underwood to oppose a bill she said would cut the Clean Water State Revolving Fund by 27 percent, as reported by Block Club Chicago. Advocates also pointed to a 2024 Environment Illinois analysis that they say found every Lake Michigan beach had at least one day with potentially unsafe fecal-indicator levels.
Why Beaches Fail Tests
High bacteria counts often follow heavy rainfall, sewage overflows or stormwater runoff that carries animal and human waste into the lake, which means a beach can fail tests even when the sky is clear and the sun is out. The U.S. Environmental Protection Agency notes that fecal indicator bacteria are used to estimate the chance that disease-causing organisms are present in recreational waters and that swim advisories are meant as a public-health protection while agencies sort out the source of contamination, according to the EPA.
What Swimmers Should Know
Swimmers are urged to check the Chicago Park District’s beach dashboard after 1:30 p.m. for same-day water-quality updates and to follow posted flags and lifeguard directions. Yellow means swim with caution; red means stay out of the water. Anyone who develops vomiting, diarrhea or fever after swimming during an advisory should contact a health care provider and mention possible waterborne exposure; additional guidance is available from state and federal public-health resources.
For now, the 31st Street advisory was short-lived, but advocates say an early-season test failure should serve as a wake-up call for policymakers and beach managers. The Park District and state health officials plan to keep up daily monitoring throughout the summer, and beachgoers are urged to consult official dashboards before taking the plunge.
