Community Water System · PWS AK2260309
Unalaska Water System
Operator location Unalaska, Alaska - larger served population (> 3,309) at 9,400 people served; 398 SDWIS violations on record from surface water sources.
- 9,400
- People served (this PWS)
- 398
- EPA violations (this PWS)
- 3
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
Unalaska Water System standing, high SDWIS violation third
9,400 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 1% is middle-third health share (≤ 23%). UCMR5: UCMR5 tested, none detected. Population rank #4,955 of 29,740 among systems serving 500+.
The verdict
Unalaska Water System sits in the upper third of the sitemap cohort by violation count (398), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is large (9,400; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 1% (middle-third health share (≤ 23%)). UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #4,955 of 29,740
- Population · /systems
- #13 of 164
- Population · AK
- 398
- Total EPA violations on record
- 1%
- 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
- 603
- County
- Aleutians West Census Area
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 288
- Treatment Tech Violations
- 3
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Surface Water Treatment Rule | MR | 12 | 2024 |
| Nitrate | MR | 11 | 2024 |
| Coliform (TCR) | MR | 9 | 2015 |
| Arsenic | MR | 8 | 2003 |
| Chlorine | MR | 8 | 2024 |
| Barium | MR | 7 | 1992 |
| Cadmium | MR | 7 | 1992 |
| Chromium | MR | 7 | 1992 |
| Selenium | MR | 7 | 1992 |
| Fluoride | MR | 7 | 1992 |
| Mercury | MR | 7 | 1992 |
| Methoxychlor | MR | 6 | 2001 |
| Toxaphene | MR | 6 | 2001 |
| 2,4,5-TP | MR | 6 | 2001 |
| 2,4-D | MR | 6 | 2001 |
| BHC-GAMMA | MR | 6 | 2001 |
| Endrin | MR | 6 | 2001 |
| p-Dichlorobenzene | MR | 5 | 1997 |
| Carbon tetrachloride | MR | 5 | 1997 |
| CHLOROBENZENE | MR | 5 | 1997 |
| Toluene | MR | 5 | 1997 |
| Tetrachloroethylene | MR | 5 | 1997 |
| Ethylbenzene | MR | 5 | 1997 |
| 1,1-Dichloroethylene | MR | 5 | 1997 |
| Trichloroethylene | MR | 5 | 1997 |
| 1,2-Dichloroethane | MR | 5 | 1997 |
| 1,1,2-Trichloroethane | MR | 5 | 1997 |
| 1,1,1-Trichloroethane | MR | 5 | 1997 |
| o-Dichlorobenzene | MR | 5 | 1997 |
| 1,2-Dichloropropane | MR | 5 | 1997 |
Violation Count vs. the National Corpus
Unalaska Water System has 398 recorded EPA violations, 94% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 6% carry more. 1% of this system's own violations are health-based (3 of 398), and it ranks #4,955 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)
398 Higher than most more violations than 94% 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
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 232 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFOS | 6/19/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| HFPO-DA | 6/19/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 6/19/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 6/19/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 6/19/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 6/19/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFDA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 6/19/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFBA | 6/19/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NEtFOSAA | 6/19/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHxS | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTrDA | 6/19/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFHpS | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 6/19/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 6/19/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFTA | 6/19/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFDoA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 6/19/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFEESA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 6/19/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 6/19/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 6/19/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 6/19/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFTrDA | 6/13/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 6/13/2024 | <8.00 ppt | 8.00 ppt | Not Detected |
| NEtFOSAA | 6/13/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 6/13/2024 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFOS | 12/29/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| ADONA | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 12/29/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 12/29/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NEtFOSAA | 12/29/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 12/29/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 12/29/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFHpS | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 12/29/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 12/29/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFEESA | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 12/29/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 12/29/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 12/29/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
Population served record for Unalaska Water System
EPA SDWIS lists 9,400 people served and 603 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS
Nationwide peers
398 violations · 9,400 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.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Unalaska Water System
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Alaska compares on the same EPA violation measures. Alaska 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.