Community Water System · PWS IL1115850
Wonder Lake (Niu)
Operator location Wonder Lake, Illinois - upper-third violation load (> 74 violations) with 402 EPA violations; groundwater source; 1,950 served (PWS-level, not municipal population).
- 1,950
- People served (this PWS)
- 402
- EPA violations (this PWS)
- 18
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Wonder Lake (Niu) standing, high SDWIS violation third
402 EPA SDWIS violations on record - upper-third violation load (> 74 violations). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 4% is middle-third health share (≤ 23%). Population rank #13,850 of 29,740 among systems serving 500+.
The verdict
Wonder Lake (Niu) sits in the upper third of the sitemap cohort by violation count (402), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is mid-pack at 1,950 (mid served population (≤ 3,309)). Health-based share is 4% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- #13,850 of 29,740
- Population · /systems
- #599 of 1,310
- Population · IL
- 402
- Total EPA violations on record
- 4%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 780
- County
- McHenry
- School/Daycare
- No
- MCL Violations
- 18
- Monitoring Violations
- 374
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| 1,2-Dichloropropane | MR | 21 | 1993 |
| Benzene | MR | 21 | 1993 |
| Ethylbenzene | MR | 21 | 1993 |
| Tetrachloroethylene | MR | 21 | 1993 |
| cis-1,2-Dichloroethylene | MR | 20 | 1993 |
| Xylenes, Total | MR | 20 | 1993 |
| o-Dichlorobenzene | MR | 20 | 1993 |
| p-Dichlorobenzene | MR | 20 | 1993 |
| 1,1-Dichloroethylene | MR | 20 | 1993 |
| trans-1,2-Dichloroethylene | MR | 20 | 1993 |
| 1,2-Dichloroethane | MR | 20 | 1993 |
| 1,1,1-Trichloroethane | MR | 20 | 1993 |
| Carbon tetrachloride | MR | 20 | 1993 |
| Trichloroethylene | MR | 20 | 1993 |
| Toluene | MR | 20 | 1993 |
| CHLOROBENZENE | MR | 20 | 1993 |
| Styrene | MR | 20 | 1993 |
| Coliform (TCR) | MR | 19 | 2002 |
| Arsenic | MCL | 12 | 2013 |
| Coliform (TCR) | MCL | 6 | 1998 |
| Lead and Copper Rule | MR | 4 | 2004 |
| Revised Total Coliform Rule | MON | 3 | 2024 |
| Chlorine | MR | 3 | 2024 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1977 |
Violation Count vs. the National Corpus
Wonder Lake (Niu) has 402 recorded EPA violations, 94% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 6% carry more. 4% of this system's own violations are health-based (18 of 402), and it ranks #13,850 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
402 Higher than most more violations than 94% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
SDWIS compliance record for Wonder Lake (Niu)
402 violations on record for IL1115850; use EPA SDWIS to confirm return-to-compliance dates and monitoring categories.
Sources: EPA SDWIS · Illinois EPA, Bureau of Water
Nationwide peers
402 violations · 1,950 served: nearest cross-state SDWIS matches.
Cross-state systems with comparable violation load
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems near this population served
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Wonder Lake
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Illinois compares on the same EPA violation measures. Illinois systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.