Community Water System · PWS MT0000341
Thompson Falls City Of
Operator location Thompson Falls, Montana - 8% of 38 violations are health-based (middle-third health share (≤ 23%)); groundwater source; 1,950 served per SDWIS.
- 1,950
- People served (this PWS)
- 38
- EPA violations (this PWS)
- 3
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Thompson Falls City Of standing, mid SDWIS violation third
8% of 38 recorded violations are health-based - middle-third health share (≤ 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 8% is middle-third health share (≤ 23%). Population rank #13,852 of 29,740 among systems serving 500+.
The verdict
Thompson Falls City Of lands in the middle third by violation volume (38), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is mid-pack at 1,950 (mid served population (≤ 3,309)). Health-based share is 8% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- #13,852 of 29,740
- Population · /systems
- #79 of 283
- Population · MT
- 38
- Total EPA violations on record
- 8%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 719
- County
- Sanders
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 30
- Treatment Tech Violations
- 3
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 8 | 2005 |
| Surface Water Treatment Rule | TT | 3 | 1999 |
| Nitrate | MR | 3 | 1996 |
| Fluoride | MR | 2 | 1994 |
| Selenium | MR | 2 | 1994 |
| Mercury | MR | 2 | 1994 |
| Chromium | MR | 2 | 1994 |
| Barium | MR | 2 | 1994 |
| Cadmium | MR | 2 | 1994 |
| Arsenic | MR | 2 | 1994 |
| Consumer Confidence Rule | Other | 2 | 2015 |
| Thallium, Total | MR | 1 | 1994 |
| Antimony, Total | MR | 1 | 1994 |
| CYANIDE | MR | 1 | 1994 |
| Beryllium, Total | MR | 1 | 1994 |
| Nickel | MR | 1 | 1994 |
Violation Count vs. the National Corpus
Thompson Falls City Of has 38 recorded EPA violations, 49% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 50% carry more. 8% of this system's own violations are health-based (3 of 38), and it ranks #13,852 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
38 Lower than most fewer violations than 50% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
Health-based violations on Thompson Falls City Of
3 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for MT0000341.
Sources: EPA SDWIS
Nationwide peers
38 violations · 1,950 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems near this population served
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Thompson Falls City Of
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Montana compares on the same EPA violation measures. Montana systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.