Montana Water Quality Brief
State: Montana (MT) Grade: F | Score: 55/100 | National Average: 67/100 (Grade: D) Data as of: 2026-04-30 | Brief generated: 2026-04-30
Key Findings
- Montana earned a water quality grade of F with an average score of 55/100 — 12 points below the national average.
- ZipCheckup recorded 2,102 total violations across 405 ZIP codes, including 431 health-based violations.
- The worst ZIP code in the state (59542) scored only 22/100, while the best (59011) scored 83/100 — a gap of 61 points.
Worst 5 ZIP Codes
| ZIP | City | County | Score | Grade | Violations |
|---|---|---|---|---|---|
| 59542 | Turner | Blaine | 22/100 | F | 13 |
| 59484 | Sweet Grass | Toole | 28/100 | F | 8 |
| 59858 | Philipsburg | Granite | 33/100 | F | 15 |
| 59035 | Fort Smith | Big Horn | 33/100 | F | 36 |
| 59004 | Ashland | Rosebud | 33/100 | F | 31 |
County Breakdown (Worst 3)
| County | Avg Score | Grade | ZIP Count | Worst ZIP |
|---|---|---|---|---|
| Blaine | 41/100 | D | 5 | 59542 (Turner, 22/100) |
| Granite | 42/100 | D | 3 | 59858 (Philipsburg, 33/100) |
| Garfield | 44/100 | D | 4 | 59322 (Cohagen, 40/100) |
Violation Summary
| Category | Count |
|---|---|
| Total violations | 2,102 |
| Health-based violations | 431 |
| Monitoring/Reporting violations | 1,671 |
| ZIP codes analyzed | 405 |
| Health violations per ZIP (avg) | 1.1 |
Top health-based violation categories:
- Stage 1 DBP Rule (372 violations across 134 ZIP codes)
- Consumer Confidence Report Rule (291 violations across 110 ZIP codes)
- Total Trihalomethanes (TTHM) (241 violations across 92 ZIP codes)
PFAS Contamination Status
- PFAS detected in 7 of 51 ZIP codes analyzed (14%).
- 4 ZIP codes with federal PFAS exceedances.
Comparison to National Average
| Metric | MT | National |
|---|---|---|
| Avg Score | 55/100 | 67/100 |
| Grade | F | D |
| Health violations / ZIP | 1.1 | — |
About This Data
Data: ZipCheckup.com | Sources: EPA SDWIS, FEMA, CDC, Census | License: CC BY 4.0
Press contact: [email protected] General contact: [email protected] State page: https://zipcheckup.com/states/montana/
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