Crystal Lake

Water Quality Snapshot: Crystal Lake

Crystal Lake is a local-owned community water system that delivers drinking water to 40,661 residents in Crystal Lake, Illinois (McHenry County) through 14,101 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 54 total violations for this system , of which 22 (41%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 28 monitoring and reporting violations are on file. The most recent violation on record dates to 1996.

The most frequently cited contaminant at this system is Barium, recorded in 19 violations (MCL, health-based). Under EPA's UCMR5 PFAS monitoring program, 2 PFAS compounds were detected in samples collected from this system, with a maximum reported concentration of 4.6 ppt (parts per trillion). PFAS are persistent synthetic chemicals linked to health effects at very low exposure levels.

Across Illinois, EPA tracks 5,117 public water systems serving 12,576,876 people, with 355,322 cumulative violations and 52,932 health-based violations on record. About 81% of systems in the state carry at least one violation, and state-wide the average per system is 69.4 violations. Statewide, 199 of 487 UCMR5-tested systems have reported PFAS detections (40.9%).

Crystal Lake's 54 violations sit below the Illinois average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.