Transient Non-Community Water System · PWS MT0042403
Big Arm Flathead Lake Mt St Pk
Operator location Kalispell, Montana - 49% of 61 violations are health-based (upper-third health share (> 23%)); groundwater source; 75 served per SDWIS.
- 75
- People served (this PWS)
- 61
- EPA violations (this PWS)
- 30
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Big Arm Flathead Lake Mt St Pk standing, mid SDWIS violation third
49% of 61 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 49% is upper-third health share (> 23%).
The verdict
Big Arm Flathead Lake Mt St Pk lands in the middle third by violation volume (61), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is smaller (75; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 49% - most of this ledger is MCL or treatment-technique exceedance. No UCMR5 PFAS test appears for this system in this extract.
- 61
- Total EPA violations on record
- 49%
- Health-based (MCL / treatment failure)
- 75
- People served by this PWS (SDWIS)
- N/A
- PFAS compounds detected (UCMR5)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Transient Non-Community
- Owner Type
- State
- Connections
- 20
- County
- Lake
- School/Daycare
- No
- MCL Violations
- 21
- Monitoring Violations
- 31
- Treatment Tech Violations
- 9
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Groundwater Rule | MR | 27 | 2018 |
| Coliform (TCR) | MCL | 21 | 2011 |
| Groundwater Rule | TT | 9 | 2018 |
| Coliform (TCR) | MR | 4 | 1996 |
Violation Count vs. the National Corpus
Big Arm Flathead Lake Mt St Pk has 61 recorded EPA violations, 62% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 38% carry more. 49% of this system's own violations are health-based (30 of 61), and it ranks unranked by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
61 Around the middle fewer violations than 38% 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 Big Arm Flathead Lake Mt St Pk
30 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for MT0042403.
Sources: EPA SDWIS
Nationwide peers
61 violations · 75 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.
What to do with Big Arm Flathead Lake Mt St Pk
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.