Clay, SD
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 Clay in South Dakota · Population: 15,133
SDWIS systems such as VERMILLION; CLAY RURAL WATER SYSTEM; CLAY RWS/SOUTH UNION anchor Clay, SD's EPA extract. Derived burden score 6/100 (Low Risk) uses fixed national caps on density, log release volume, Superfund count, and health-flagged systems - not an official EPA rating.
No TRI Form R facilities sit in Clay in this extract; water coverage still lists VERMILLION; CLAY RURAL WATER SYSTEM; CLAY RWS/SOUTH UNION. AQS monitors logged median AQI 39 / peak 137 in 2024.
Burden score 6/100 (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 Clay -- 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.
Air Quality History (2022–2024)
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 | 289 (79%) | 75 | 2 | 137 |
| 2023 | 244 (67%) | 103 | 15 | 173 |
| 2022 | 320 (88%) | 45 | 0 | 87 |
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 South Dakota, see the EPA's AirNow.gov.
Water Systems (7)
| System | System pop (SDWIS) | Violations |
|---|---|---|
| VERMILLION | 11,695 | 0 |
| CLAY RURAL WATER SYSTEM | 4,780 | 0 |
| CLAY RWS/SOUTH UNION | 1,447 | 0 |
| WAKONDA | 276 | 3 |
| MASKELL, VILLAGE OF | 86 | 10 |
| LEWIS AND CLARK REGIONAL WATER SYSTEM | 25 | 0 |
| LEWIS AND CLARK REGIONAL WATER SYSTE | 0 | 0 |
Cities in Clay (2)
Frequently Asked Questions
What is the environmental risk level in Clay, South Dakota? ▼
Are there Superfund sites in Clay? ▼
How many toxic release facilities are in Clay? ▼
What is the air quality in Clay? ▼
Is the drinking water safe in Clay? ▼
What environmental agencies cover Clay? ▼
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.