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Community Water System · PWS MA4221000

Oak Bluffs Water District

Operator location Oak Bluffs, Massachusetts - UCMR5 detected 2 PFAS compounds (lower-third PFAS panel (≤ 2 compounds)) on this PWS; SDWIS lists 167 violations and 24,000 people served.

24,000
People served (this PWS)
167
EPA violations (this PWS)
29
Health-based (this PWS)
2 PFAS
UCMR5 (this PWS)
Follow published updates (RSS)

Oak Bluffs Water District standing, high SDWIS violation third

UCMR5 detected 2 PFAS compounds - lower-third PFAS panel (≤ 2 compounds). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 17% is middle-third health share (≤ 23%). UCMR5: lower-third PFAS panel (≤ 2 compounds). Population rank #2,328 of 29,740 among systems serving 500+.

The verdict

Oak Bluffs Water District sits in the upper third of the sitemap cohort by violation count (167), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is large (24,000; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 17% (middle-third health share (≤ 23%)). UCMR5 detected 2 PFAS compounds (lower-third PFAS panel (≤ 2 compounds)).

#2,328 of 29,740
Population · /systems
#98 of 418
Population · MA
167
Total EPA violations on record
17%
Health-based (MCL / treatment failure)

Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.

PFAS Detected

2 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.

System Details

System Type
Community
Owner Type
Local
Connections
4,628
County
Dukes
School/Daycare
No
MCL Violations
29
Monitoring Violations
114
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MCL 29 2013
Coliform (TCR) MR 22 2009
Lead and Copper Rule MR 4 2010
Nitrate MR 3 2010
Tetrachloroethylene MR 3 2010
Carbon tetrachloride MR 2 2010
1,1-Dichloroethylene MR 2 2010
1,2-Dichloroethane MR 2 2010
1,1,1-Trichloroethane MR 2 2010
Vinyl chloride MR 2 2010
o-Dichlorobenzene MR 2 2010
cis-1,2-Dichloroethylene MR 2 2010
1,2-Dichloropropane MR 2 2010
Ethylbenzene MR 2 2010
Toluene MR 2 2010
p-Dichlorobenzene MR 2 2010
1,2,4-Trichlorobenzene MR 2 2010
TTHM MR 2 2014
Coliform (TCR) Other 2 2006
Trichloroethylene MR 2 2010
Styrene MR 2 2010
1,1,2-Trichloroethane MR 2 2010
Public Notice Other 2 2009
Benzene MR 2 2010
Consumer Confidence Rule Other 2 2015
CHLOROBENZENE MR 2 2010
trans-1,2-Dichloroethylene MR 2 2010
Xylenes, Total MR 2 2010
DICHLOROMETHANE MR 2 2010
Selenium MR 1 1990

Violation Count vs. the National Corpus

Oak Bluffs Water District has 167 recorded EPA violations, 83% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 17% carry more. 17% of this system's own violations are health-based (29 of 167), and it ranks #2,328 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)

167 Higher than most more violations than 83% 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. 4 of 290 samples detected PFAS.

Contaminant Date Result MRL Status
PFPeA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFMBA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFEESA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
NFDHA 6/21/2023 <20.00 ppt 20.00 ppt Not Detected
PFPeS 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
PFHpS 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
NMeFOSAA 6/21/2023 <6.00 ppt 6.00 ppt Not Detected
PFTrDA 6/21/2023 <7.00 ppt 7.00 ppt Not Detected
NEtFOSAA 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFMPA 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
PFTA 6/21/2023 <8.00 ppt 8.00 ppt Not Detected
PFOA 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
8:2 FTS 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
6:2 FTS 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFDA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFOS 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
PFNA 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
PFHxS 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFBS 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
4:2 FTS 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFUnA 6/21/2023 <2.00 ppt 2.00 ppt Not Detected
11Cl-PF3OUdS 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
9Cl-PF3ONS 6/21/2023 <2.00 ppt 2.00 ppt Not Detected
ADONA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFHpA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFBA 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFHxA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFDoA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
ADONA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
9Cl-PF3ONS 6/21/2023 <2.00 ppt 2.00 ppt Not Detected
PFOS 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
11Cl-PF3OUdS 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFBA 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFHxA 6/21/2023 3.00 ppt 3.00 ppt Detected
8:2 FTS 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
NMeFOSAA 6/21/2023 <6.00 ppt 6.00 ppt Not Detected
NEtFOSAA 6/21/2023 <5.00 ppt 5.00 ppt Not Detected
PFTrDA 6/21/2023 <7.00 ppt 7.00 ppt Not Detected
PFTA 6/21/2023 <8.00 ppt 8.00 ppt Not Detected
PFOA 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
PFDA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFUnA 6/21/2023 <2.00 ppt 2.00 ppt Not Detected
PFHpS 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
4:2 FTS 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFMPA 6/21/2023 <4.00 ppt 4.00 ppt Not Detected
PFPeA 6/21/2023 3.00 ppt 3.00 ppt Detected
PFMBA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected
PFEESA 6/21/2023 <3.00 ppt 3.00 ppt Not Detected

UCMR5 PFAS record for Oak Bluffs Water District

Open EPA SDWIS federal reports for PWS MA4221000 to cross-check UCMR5 detections and violation codes; state primacy agencies enforce the Safe Drinking Water Act locally.

EPA SDWIS · PWS MA4221000 MA primacy agency

Sources: EPA SDWIS · MassDEP, Drinking Water Program

Nationwide peers

167 violations · 24,000 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.

4 peers

Cross-state systems with similar served population

Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).

4 peers

What to do with Oak Bluffs Water District

Use this system's EPA-reported record as a starting filter, not a final verdict.

EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater