Community Water System · PWS IL0991150
Tonica
Operator location Tonica, Illinois - 66% of 129 violations are health-based (upper-third health share (> 23%)); groundwater source; 705 served per SDWIS.
- 705
- People served (this PWS)
- 129
- EPA violations (this PWS)
- 85
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Tonica standing, high SDWIS violation third
66% of 129 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 66% is upper-third health share (> 23%). Population rank #24,178 of 29,740 among systems serving 500+.
The verdict
Tonica sits in the upper third of the sitemap cohort by violation count (129), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (705; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 66% - most of this ledger is MCL or treatment-technique exceedance. No UCMR5 PFAS test appears for this system in this extract.
- #24,178 of 29,740
- Population · /systems
- #1,084 of 1,310
- Population · IL
- 129
- Total EPA violations on record
- 66%
- 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
- 340
- County
- LaSalle
- School/Daycare
- No
- MCL Violations
- 85
- Monitoring Violations
- 31
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Arsenic | MCL | 72 | 2009 |
| Coliform (TCR) | MR | 15 | 2012 |
| Coliform (TCR) | MCL | 8 | 1997 |
| Public Notice | Other | 6 | 2006 |
| Chlorine | MR | 6 | 2012 |
| Arsenic | MR | 5 | 2006 |
| Nitrite | MCL | 5 | 2011 |
| Nitrate | MR | 4 | 2005 |
| Consumer Confidence Rule | Other | 2 | 2013 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1977 |
Violation Count vs. the National Corpus
Tonica has 129 recorded EPA violations, 78% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 22% carry more. 66% of this system's own violations are health-based (85 of 129), and it ranks #24,178 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)
129 Higher than most more violations than 78% 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
Health-based violations on Tonica
85 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for IL0991150.
Sources: EPA SDWIS · Illinois EPA, Bureau of Water
Nationwide peers
129 violations · 705 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 with smaller service footprints
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Tonica
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.