Mason, MI
Transparent derived index from EPA TRI / SDWIS / Superfund extracts: not an official EPA rating. Fixed caps: facilities ≤25 pts (50+ = max), log10 releases ≤25 pts, Superfund ≤25 pts (5/site), health-violation systems ≤15 pts (3/system), high-chemical facilities ≤10 pts. Bands: High ≥60, Moderate ≥30. See methodology.
Environmental data for Mason in Michigan · Population: 29,177
TRI sites such as Great Lakes Castings LLC; Occidental Chemical Corp; House of Flavors; SDWIS systems such as LUDINGTON; SCOTTVILLE, CITY OF; PERE MARQUETTE TWP - WELLS; NPL sites such as Mason County Landfill anchor Mason, MI's EPA extract. Derived burden score 24/100 (Low Risk) uses fixed national caps on density, log release volume, Superfund count, and health-flagged systems - not an official EPA rating.
Great Lakes Castings LLC; Occidental Chemical Corp; House of Flavors are among the largest Form R filers reporting in Mason; no SDWIS system here carries an active health-based flag. AQS median AQI 37 / peak 97 in 2024.
Burden score 24/100 (Low Risk) is the only weighted composite on this page. The tables below list every TRI facility, SDWIS system, and Superfund site EPA has on record for Mason -- not just the names called out above -- reproducing the disclosure history as filed, not a current-safety verdict. Extract current as of 2026-08-25.
Release-over-release change
What changed for Mason, MI: EPA TRI 2023 reporting year
Same facilities, both years
+1.0%
2 facilities that filed in 2022 and 2023
Whole inventory
+11.3%
58.3 thousand lb → 64.9 thousand lb, every facility that filed
Between the two reporting years, 1 facility filed for the first time and 0 stopped filing. Facilities entering or leaving the inventory are excluded from the same-facility comparison above.
- Mason, MI's total reported releases rose from 58.3 thousand lb in 2022 to 58.9 thousand lb in 2023, based on EPA TRI filings.
- Mason, MI's off-site transfers rose from 25.6 thousand lb in 2022 to 29.4 thousand lb in 2023, based on EPA TRI filings.
- Mason, MI's water releases fell from 27.4 thousand lb in 2022 to 24.3 thousand lb in 2023, based on EPA TRI filings.
- Mason, MI's air releases fell from 2.2 thousand lb in 2022 to 2.0 thousand lb in 2023, based on EPA TRI filings.
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 (89%) | 26 | 0 | 97 |
| 2023 | 178 (81%) | 41 | 2 | 143 |
| 2022 | 219 (93%) | 15 | 1 | 161 |
| 2021 | 206 (85%) | 34 | 3 | 115 |
| 2020 | 229 (91%) | 20 | 1 | 159 |
Source: 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 Michigan, see the EPA's AirNow.gov.
Water Systems (6)
| System | System pop (SDWIS) | Violations |
|---|---|---|
| LUDINGTON | 8,184 | 0 |
| SCOTTVILLE, CITY OF | 1,536 | 0 |
| PERE MARQUETTE TWP - WELLS | 455 | 0 |
| PERE MARQUETTE TWP - CUSTOMER | 339 | 0 |
| HOLIDAY VILLAGE MOBILE HOME PARK | 185 | 0 |
| TALL OAKS CONDOMINUMS | 65 | 0 |
TRI Facilities (4)
| # | Facility | Total Releases |
|---|---|---|
| 1 | Great Lakes Castings LLC | 154.5K lbs |
| 2 | Occidental Chemical Corp | 122.0K lbs |
| 3 | House of Flavors | 6.0K lbs |
| 4 | Cone Drive Operations Inc | 24 lbs |
Superfund Sites (1)
| Site Name | Status | HRS Score |
|---|---|---|
| Mason County Landfill | Deleted NPL Site | 34.18 |
Cities in Mason (3)
Frequently Asked Questions
What is the environmental risk level in Mason, Michigan? ▼
Are there Superfund sites in Mason? ▼
How many toxic release facilities are in Mason? ▼
What is the air quality in Mason? ▼
Is the drinking water safe in Mason? ▼
What environmental agencies cover Mason? ▼
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.