Public water system · WA5362650
ActiveOak Harbor City of
At a glance
City of Oak Harbor (PWSID WA5362650) is an active community water system in Island County, Washington. It reports serving 23,675 people through 8,886 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
23,675
Service connections
8,886
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does City of Oak Harbor compare with other water systems in Island County?
By EPA's size categories, City of Oak Harbor is a large system (10,001 to 100,000 people). Island County has 307 active public water systems, and City of Oak Harbor is the largest of them by population served. Its population served is about 71 times the county average of 335 people per system, and accounts for 23% of the 102,977 people reported by systems filed under the county. Across Washington, the 4,705 active systems average 2,172 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Oak Harbor is about 3.5 times that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Washington has 2,392 active community water systems, 51% of the state's 4,705 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 130 Washington systems (2.8%) list purchased surface water as their primary source.
Who owns and regulates City of Oak Harbor?
EPA lists City of Oak Harbor as owned by a local government. The WA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 27 of the 307 active systems in Island County (8.8%) are also owned by a local government.
Does City of Oak Harbor have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2025. The violations listed here began between November 1991 and October 2025. By type: 11 monitoring and reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (8 of them). EPA lists 9 as archived and 3 as resolved. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Archived |
| 2025-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Archived |
| 2024-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2013-08-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1994-02-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-09-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-07-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-02-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-01-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1991-12-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1991-11-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
City of Oak Harbor: frequently asked questions
Who runs City of Oak Harbor?
City of Oak Harbor (PWSID WA5362650) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does City of Oak Harbor serve?
City of Oak Harbor reports serving 23,675 people through 8,886 service connections in Island County, Washington.
Where does City of Oak Harbor get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does City of Oak Harbor have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2025. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is City of Oak Harbor's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the WA state drinking water program.
Where can I find City of Oak Harbor's water quality report?
As a community water system, City of Oak Harbor must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Island County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Naval Air Station/Whidbey Island | Island | 16,595 | Community | Purchased surface water |
| Coupeville Town of | Island | 4,142 | Community | Groundwater |
| Camano Water Association | Island | 2,592 | Community | Groundwater |
| Clinton Water District | Island | 1,980 | Community | Groundwater |
| Camano Island State Park | Island | 1,718 | Transient non-community | Groundwater |
| Maxwelton Water System | Island | 1,700 | Non-transient non-community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Oak Harbor City of, PWSID WA5362650, Washington”, https://aquacensus.com/water-systems/washington/oak-harbor-city-of-wa5362650 (data as of October 1, 2026).