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Isle au Haut, ME Tap Water Quality 2026

Water quality report for Isle au Haut, ME — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Isle au Haut's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Stonington Water Company PWSID: ME0091510 Updated: 2026 Q2
✅

No federal limits exceeded on record

Lead is 1.30 ppb, 9% of the action level and no violations are open. PFAS has never been sampled at this system.

C

Isle au Haut earns a C for water quality

Graded on violations and lead, with state inspection findings. PFAS not tested.

Lead: 1.30 ppb — 9% of the federal action level
PFAS never sampled at this system
11 violations since 2015, 5 health-based
No violations currently open
Isle au Haut's lead level vs. all Maine community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: 1.30 ppb — 9% of the federal action level
✓ Lower lead than 85% of Maine utilities
Population Served
15
~273 connections
Water Source
Groundwater
Drawn from wells — SDWIS source code GW
Active Violations
0
11 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)
90th percentile of tap samples collected across the distribution system
9% of EPA action level
1.30 ppb
Action level: 15 ppb
Copper (Cu)
90th percentile of tap samples. SDWIS reports a copper figure only when a system exceeds the action level, so any value here is an exceedance.
140.8% of EPA action level
1,830 ppb
Action level: 1,300 ppb
The 90th-percentile lead result is 1.30 ppb, 9% of the 15 ppb federal action level. The action level is a treatment trigger, not a legal maximum, and it is measured across sampled taps rather than at any single home. Copper reached the action level here; a copper figure appears in SDWIS only when a system triggers it.

Contaminant Violations (2015–Present)

ContaminantTypeMeasuredLimitPeriodStatus
TTHM MCL EXCEEDANCE 0.083 MG/L 0.080 mg/L 2023 Archived
Total Haloacetic Acids (HAA5) MONITORING AND REPORTING — 0.060 mg/L 2023 Resolved
TTHM MONITORING AND REPORTING — 0.080 mg/L 2023 Resolved
Gross Alpha, Excl. Radon and U MCL EXCEEDANCE 27 PCI/L 15 pCi/L 2021 Resolved
Revised Total Coliform Rule MCL EXCEEDANCE — — 2020 Resolved
Total Haloacetic Acids (HAA5) MONITORING AND REPORTING — 0.060 mg/L 2019 Resolved
TTHM MONITORING AND REPORTING — 0.080 mg/L 2019 Resolved
Lead and Copper Rule MONITORING AND REPORTING — TT 2019 Resolved
Combined Radium (-226 and -228) MONITORING AND REPORTING — 5 pCi/L 2019 Resolved
Gross Alpha, Excl. Radon and U MCL EXCEEDANCE 29 PCI/L 15 pCi/L 2019 Resolved
Gross Alpha, Excl. Radon and U MCL EXCEEDANCE 25 PCI/L 15 pCi/L 2018 Resolved
Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

11 violations are on record since 2015, of which 5 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Stonington Water Company
PWSID ME0091510
Water source Groundwater — Drawn from wells — SDWIS source code GW
Population served 15
Service connections 273
Systems serving this area 1
Regulator State primacy agency
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Isle au Haut tap water safe to drink? ▼
No federal limit is exceeded on record. No violations are currently open. Lead is 1.30 ppb, 9% of the action level.
Does Isle au Haut water have PFAS? ▼
This system has never been sampled for PFAS. EPA's national monitoring covered systems serving 3,300 people or more, so no results exist — which is not evidence that none is present.
Who supplies water to Isle au Haut? ▼
Stonington Water Company (PWSID ME0091510). Groundwater. Drawn from wells — SDWIS source code GW
When was this system last inspected? ▼
It was last inspected on 2025-05-21. No significant deficiencies were recorded.

What Should Isle au Haut Residents Do?

1
Read your annual water report
Your supplier publishes a Consumer Confidence Report each July covering the prior year.
2
Check for a lead service line
Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.
3
Flush before drinking
If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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