St. Clair, IL
A PlainEnviro-computed score from reported facility/violation counts, not an official EPA rating, health forecast, or population-adjusted rate. See methodology. This is a different measure than the EJ Screening score for this county, which ranks it by percentile against every other tracked county rather than against fixed national thresholds.
Environmental data for St. Clair in Illinois · Population: 254,777
St. Clair, IL is tracked across three EPA datasets covering 27 Toxics Release Inventory (TRI) facilities, 22 Safe Drinking Water Act systems, and 0 Superfund National Priorities List sites. Together these generate an environmental burden score of 59/100 (Moderate Risk), calibrated against national distributions for facility density, chemical release volume, Superfund concentration, and water-system health violations.
Industrial disclosures inside the county total 3.8M lbs of reported toxic releases under EPCRA Section 313, while 9 water systems carry an active health-based violation in the SDWIS record. EPA Air Quality System monitors logged a median AQI of 46 and a peak AQI of 112 in 2024, with 60% of observed days rated "Good" (0–50).
All figures below draw directly from federal EPA records, TRI self-reported emissions, SDWIS compliance history, NPL Hazard Ranking System scores, and AQS daily AQI summaries, and are not adjusted, weighted, or forecast. A past violation or elevated score does not itself indicate current unsafe conditions; it documents the regulatory and disclosure history publicly filed with the U.S. Environmental Protection Agency through the most recent reporting cycle.
Air Quality History (2020–2024)
EPA Air Quality Index (AQI) data showing how many days per year fall into each air quality category.
| Year | Good | Moderate | Unhealthy (SG) | Max AQI |
|---|---|---|---|---|
| 2024 | 218 (60%) | 145 | 3 | 112 |
| 2023 | 128 (35%) | 223 | 12 | 169 |
| 2022 | 165 (45%) | 199 | 1 | 105 |
| 2021 | 141 (39%) | 221 | 2 | 185 |
| 2020 | 260 (71%) | 105 | 0 | 100 |
Source: EPA Air Quality System (AQS) Annual AQI by County EPA Air Quality System (AQS) Annual AQI by County AQI categories: Good (0-50), Moderate (51-100), Unhealthy for Sensitive Groups (101-150), Unhealthy (151-200), Very Unhealthy (201-300), Hazardous (301+)
For real-time air quality readings and pollutant breakdowns in Illinois, see the EPA's AirNow.gov.
Water Systems (22)
| System | Population | Violations |
|---|---|---|
| O FALLON | 46,603 | 2 |
| CAHOKIA HEIGHTS | 15,250 | 0 |
| CASEYVILLE | 13,798 | 3 |
| MASCOUTAH | 8,759 | 0 |
| AMERICAN WATER OPER AND MAINTENANCE, LLC | 6,779 | 0 |
| LEBANON | 4,714 | 0 |
| FREEBURG | 4,707 | 0 |
| DUPO | 4,684 | 0 |
| MILLSTADT | 4,071 | 0 |
| SMITHTON | 4,006 | 0 |
| TRENTON | 2,742 | 16 |
| NEW ATHENS | 1,970 | 3 |
| MARISSA | 1,921 | 2 |
| LENZBURG | 680 | 3 |
| ST LIBORY | 628 | 0 |
| SOUTHWESTERN IL CORRECTIONAL CENTER | 563 | 0 |
| FAYETTEVILLE | 441 | 2 |
| S L M WATER COMMISSION | 385 | 0 |
| ARAPAHO VILLAGE MHP | 368 | 0 |
| SUMMERFIELD | 347 | 0 |
| FSH WATER COMMISSION | 313 | 2 |
| KASKASKIA WATER DISTRICT | 0 | 2 |
TRI Facilities (27)
| # | Facility | Total Releases |
|---|---|---|
| 1 | Veolia N.a. Inc. | 1.9M lbs |
| 2 | Afton Chemical Corp | 1.3M lbs |
| 3 | Occidental Chemical Corp Sauget Plant | 340.7K lbs |
| 4 | Flexsys America LP Krummrich | 62.5K lbs |
| 5 | Solvay Fluorides LLC | 57.4K lbs |
| 6 | Allnex USA Inc. | 35.8K lbs |
| 7 | Phillips 66 Co East St Louis Terminal | 28.2K lbs |
| 8 | Roho West | 24.3K lbs |
| 9 | Custom Marble Inc | 23.9K lbs |
| 10 | Kempen Paint Co | 9.9K lbs |
| 11 | Center Ethanol Co LLC | 8.2K lbs |
| 12 | Gateway Terminals LLC | 6.5K lbs |
| 13 | Kettler Casting Co Inc. | 4.8K lbs |
| 14 | Hawkins Inc. - Dupo | 2.3K lbs |
| 15 | Chemtrade Solutions Llc-East St Louis | 1.5K lbs |
| 16 | Videojet Technologies Inc | 1.2K lbs |
| 17 | Cerro Flow Products LLC | 559 lbs |
| 18 | US Air Force/scott Air Force Base | 504 lbs |
| 19 | Brenntag Mid-South Inc. | 65 lbs |
| 20 | Solutia Inc P2S5 Plant | 42 lbs |
| 21 | Hubbell-Wiegmann | 32 lbs |
| 22 | Belleville Shoe Manufacturing Co | 10 lbs |
| 23 | Siemens Mfg Co Inc | 2 lbs |
| 24 | Oldcastle Lawn & Garden | 0 lbs |
| 25 | Brenntag Mid-South Inc | 0 lbs |
| 26 | Century Castings Corp | 0 lbs |
| 27 | East Side Jersey Dairy | 0 lbs |
Cities in St. Clair (13)
Frequently Asked Questions
What is the environmental risk level in St. Clair, Illinois? ▼
Are there Superfund sites in St. Clair? ▼
How many toxic release facilities are in St. Clair? ▼
What is the air quality in St. Clair? ▼
Is the drinking water safe in St. Clair? ▼
What environmental agencies cover St. Clair? ▼
What does this county environmental profile show?
This county environmental profile rolls up EPA Toxics Release Inventory facility reports, Safe Drinking Water Information System public-water-system filings, and Superfund National Priorities List sites for the county boundary defined by the U.S. Census Bureau. Facility counts reflect facilities with a reporting address inside the county, not where downstream environmental effects may be observed. Population figures are from the most recent Census ACS 5-year estimate. The county detail page is updated whenever the upstream EPA programs publish revised data; see the methodology page for the documented ingest cadence and the editorial choices governing how aggregations are computed.
Read our methodology - how this data is sourced, computed, and verified.