Custer, ID
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 Custer in Idaho · Population: 4,411
TRI sites such as Thompson Creek Mining Co; SDWIS systems such as CHALLIS CITY OF; MACKAY CITY OF; ROUND VALLEY WATER ASSN anchor Custer, ID's EPA extract. Derived burden score 19/100 (Low Risk) uses fixed national caps on density, log release volume, Superfund count, and health-flagged systems - not an official EPA rating.
Thompson Creek Mining Co is among the largest Form R filers reporting in Custer; no SDWIS system here carries an active health-based flag. AQS median AQI 6 / peak 152 in 2024.
Burden score 19/100 (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 Custer -- 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 Custer, ID: EPA TRI 2023 reporting year
Same facilities, both years
+181.6%
1 facilities that filed in 2022 and 2023
Whole inventory
+181.6%
62.2 thousand lb → 175.2 thousand lb, every facility that filed
- Custer, ID's total reported releases rose from 62.2 thousand lb in 2022 to 175.2 thousand lb in 2023, based on EPA TRI filings.
- Custer, ID's water releases rose from 0 lb in 2022 to 29.3 thousand lb in 2023, based on EPA TRI filings.
- Custer, ID's land releases rose from 62.2 thousand lb in 2022 to 146.0 thousand lb in 2023, based on EPA TRI filings.
- Custer, ID's chemicals reported fell from 2 in 2022 to 1 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 | 94 (86%) | 9 | 5 | 152 |
| 2023 | 103 (99%) | 1 | 0 | 60 |
| 2022 | 98 (93%) | 7 | 0 | 98 |
| 2021 | 93 (85%) | 17 | 0 | 99 |
| 2020 | 105 (91%) | 7 | 3 | 126 |
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 Idaho, see the EPA's AirNow.gov.
Water Systems (3)
| System | System pop (SDWIS) | Violations |
|---|---|---|
| CHALLIS CITY OF | 900 | 0 |
| MACKAY CITY OF | 566 | 0 |
| ROUND VALLEY WATER ASSN | 125 | 0 |
TRI Facilities (1)
| # | Facility | Total Releases |
|---|---|---|
| 1 | Thompson Creek Mining Co | 1.1M lbs |
Cities in Custer (3)
Frequently Asked Questions
What is the environmental risk level in Custer, Idaho? ▼
Are there Superfund sites in Custer? ▼
How many toxic release facilities are in Custer? ▼
What is the air quality in Custer? ▼
Is the drinking water safe in Custer? ▼
What environmental agencies cover Custer? ▼
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.