Non-Transient Non-Community Water System · PWS OR4190178
Coe McNary Dam
Operator location Walla Walla, Oregon - smaller served population (≤ 999) at 120 people served; 463 SDWIS violations on record from groundwater sources.
- 120
- People served (this PWS)
- 463
- EPA violations (this PWS)
- 3
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Coe McNary Dam standing, high SDWIS violation third
120 people served (SDWIS) - smaller served population (≤ 999). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 1% is middle-third health share (≤ 23%).
The verdict
Coe McNary Dam sits in the upper third of the sitemap cohort by violation count (463), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (120; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 1% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- 463
- Total EPA violations on record
- 1%
- Health-based (MCL / treatment failure)
- 120
- 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
- Federal
- Connections
- 6
- County
- Umatilla
- School/Daycare
- No
- MCL Violations
- 3
- Monitoring Violations
- 454
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 11 | 2006 |
| Nitrate | MR | 11 | 2006 |
| Carbon tetrachloride | MR | 8 | 2005 |
| cis-1,2-Dichloroethylene | MR | 8 | 2005 |
| Ethylbenzene | MR | 8 | 2005 |
| p-Dichlorobenzene | MR | 8 | 2005 |
| Styrene | MR | 8 | 2005 |
| Toluene | MR | 8 | 2005 |
| Xylenes, Total | MR | 8 | 2005 |
| Trichloroethylene | MR | 8 | 2005 |
| Vinyl chloride | MR | 8 | 2005 |
| o-Dichlorobenzene | MR | 8 | 2005 |
| trans-1,2-Dichloroethylene | MR | 8 | 2005 |
| 1,2-Dichloroethane | MR | 8 | 2005 |
| 1,1,1-Trichloroethane | MR | 8 | 2005 |
| 1,2-Dichloropropane | MR | 8 | 2005 |
| 1,1,2-Trichloroethane | MR | 8 | 2005 |
| Benzene | MR | 8 | 2005 |
| Benzo(a)pyrene | MR | 8 | 2014 |
| 1,1-Dichloroethylene | MR | 8 | 2005 |
| Tetrachloroethylene | MR | 8 | 2005 |
| DICHLOROMETHANE | MR | 8 | 2005 |
| CHLOROBENZENE | MR | 8 | 2005 |
| 1,2,4-Trichlorobenzene | MR | 8 | 2005 |
| 2,4-D | MR | 7 | 2005 |
| 2,4,5-TP | MR | 7 | 2005 |
| BHC-GAMMA | MR | 7 | 2005 |
| Carbofuran | MR | 7 | 2005 |
| Dinoseb | MR | 7 | 2005 |
| Diquat | MR | 7 | 2005 |
Violation Count vs. the National Corpus
Coe McNary Dam has 463 recorded EPA violations, 95% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 5% carry more. 1% of this system's own violations are health-based (3 of 463), 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)
463 Higher than most more violations than 95% 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
Population served record for Coe McNary Dam
EPA SDWIS lists 120 people served and 6 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS
Nationwide peers
463 violations · 120 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 Coe McNary Dam
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Oregon compares on the same EPA violation measures. Oregon 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.