Non-Transient Non-Community Water System · PWS MT0003790
Harrison School District No 23
Operator location Harrison, Montana - 0% of 1,139 violations are health-based (lower-third health share (≤ 1%)); groundwater source; 100 served per SDWIS.
- 100
- People served (this PWS)
- 1,139
- EPA violations (this PWS)
- 1
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Harrison School District No 23 standing, high SDWIS violation third
0% of 1,139 recorded violations are health-based - lower-third health share (≤ 1%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 0% is lower-third health share (≤ 1%).
The verdict
Harrison School District No 23 sits in the upper third of the sitemap cohort by violation count (1,139), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (100; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is only 0% - almost all of this trail is monitoring or reporting. No UCMR5 PFAS test appears for this system in this extract.
- 1,139
- Total EPA violations on record
- 0%
- Health-based (MCL / treatment failure)
- 100
- 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
- Non-Transient Non-Community
- Owner Type
- Local
- Connections
- 1
- County
- Madison
- School/Daycare
- Yes
- MCL Violations
- 1
- Monitoring Violations
- 1,138
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Di(2-ethylhexyl) phthalate | MR | 39 | 2020 |
| Revised Total Coliform Rule | MON | 26 | 2025 |
| Endrin | MR | 24 | 2020 |
| Dalapon | MR | 24 | 2020 |
| Di(2-ethylhexyl) adipate | MR | 24 | 2020 |
| OXAMYL | MR | 24 | 2020 |
| Picloram | MR | 24 | 2020 |
| Dinoseb | MR | 24 | 2020 |
| Hexachlorocyclopentadiene | MR | 24 | 2020 |
| Heptachlor | MR | 24 | 2020 |
| HEXACHLOROBENZENE | MR | 24 | 2020 |
| Benzo(a)pyrene | MR | 24 | 2020 |
| Pentachlorophenol | MR | 24 | 2020 |
| Chlordane | MR | 24 | 2020 |
| BHC-GAMMA | MR | 24 | 2020 |
| Toxaphene | MR | 24 | 2020 |
| Simazine | MR | 24 | 2020 |
| Carbofuran | MR | 24 | 2020 |
| Heptachlor epoxide | MR | 24 | 2020 |
| 2,4-D | MR | 24 | 2020 |
| 2,4,5-TP | MR | 24 | 2020 |
| LASSO | MR | 24 | 2020 |
| Methoxychlor | MR | 24 | 2020 |
| Atrazine | MR | 24 | 2020 |
| cis-1,2-Dichloroethylene | MR | 21 | 2020 |
| Xylenes, Total | MR | 21 | 2020 |
| Vinyl chloride | MR | 21 | 2020 |
| 1,1-Dichloroethylene | MR | 21 | 2020 |
| trans-1,2-Dichloroethylene | MR | 21 | 2020 |
| 1,2-Dichloroethane | MR | 21 | 2020 |
Violation Count vs. the National Corpus
Harrison School District No 23 has 1,139 recorded EPA violations, 99% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 1% carry more. 0% of this system's own violations are health-based (1 of 1,139), 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)
1,139 Higher than most more violations than 99% 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 Harrison School District No 23
1 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for MT0003790.
Sources: EPA SDWIS
Nationwide peers
1,139 violations · 100 served: nearest cross-state SDWIS matches.
Cross-state systems with comparable violation load
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
What to do with Harrison School District No 23
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.