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Community Water System · PWS WA5362675

Oak Park

Shelton, Washington 98584-5034 - drinking water served from groundwater sources to 695 people, tracked in EPA SDWIS and UCMR5.

695
People served
61
EPA violations
2
Health-based
Untested
UCMR5 result

The verdict

EPA records 61 drinking-water violations at Oak Park, 3% of them health-based - below the Washington per-system average.

61
Total EPA violations on record
3%
Health-based (MCL / treatment failure)
695
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Oak Park

Oak Park is a private-owned community water system that delivers drinking water to 695 residents in Shelton, Washington (Mason County) through 227 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 61 total violations for this system , of which 2 (3%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 55 monitoring and reporting violations are on file. The most recent violation on record dates to 2022.

The most frequently cited contaminant at this system is Nitrate, recorded in 3 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Washington, EPA tracks 4,557 public water systems serving 9,736,844 people, with 314,648 cumulative violations and 20,590 health-based violations on record. About 92% of systems in the state carry at least one violation, and state-wide the average per system is 69 violations. Statewide, 98 of 247 UCMR5-tested systems have reported PFAS detections (39.7%).

Oak Park's 61 violations sit below the Washington average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
695
Total Violations
61
Health-Based Violations
2
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
227
County
Mason
School/Daycare
No
MCL Violations
2
Monitoring Violations
55
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Nitrate MR 3 2022
o-Dichlorobenzene MR 2 2011
1,1-Dichloroethylene MR 2 2011
trans-1,2-Dichloroethylene MR 2 2011
1,2-Dichloroethane MR 2 2011
1,1,1-Trichloroethane MR 2 2011
1,2-Dichloropropane MR 2 2011
Trichloroethylene MR 2 2011
Benzene MR 2 2011
Toluene MR 2 2011
Ethylbenzene MR 2 2011
1,2,4-Trichlorobenzene MR 2 2011
DICHLOROMETHANE MR 2 2011
p-Dichlorobenzene MR 2 2011
Carbon tetrachloride MR 2 2011
1,1,2-Trichloroethane MR 2 2011
CHLOROBENZENE MR 2 2011
Styrene MR 2 2011
Coliform (TCR) MR 2 1992
Coliform (TCR) MCL 2 1995
Vinyl chloride MR 2 2011
cis-1,2-Dichloroethylene MR 2 2011
Tetrachloroethylene MR 2 2011
Consumer Confidence Rule Other 1 1999
Revised Total Coliform Rule MON 1 2018
Cadmium MR 1 1979
Mercury MR 1 1979
Barium MR 1 1979
Selenium MR 1 1979
Chromium MR 1 1979

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Oak Park.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID WA5362675 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Washington Drinking Water Authority

Washington State Department of Health, Office of Drinking Water is the primacy agency that licenses and inspects Oak Park under EPA-delegated authority.

Open WA regulator portal

Source: Washington State Department of Health, Office of Drinking Water

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2022 Nitrate MR 3 SDWIS / WA5362675 / 1040
2018 Revised Total Coliform Rule MON 1 SDWIS / WA5362675 / 8000
2011 o-Dichlorobenzene MR 2 SDWIS / WA5362675 / 2968
2011 1,1-Dichloroethylene MR 2 SDWIS / WA5362675 / 2977
2011 trans-1,2-Dichloroethylene MR 2 SDWIS / WA5362675 / 2979
2011 1,2-Dichloroethane MR 2 SDWIS / WA5362675 / 2980
2011 1,1,1-Trichloroethane MR 2 SDWIS / WA5362675 / 2981
2011 1,2-Dichloropropane MR 2 SDWIS / WA5362675 / 2983
2011 Trichloroethylene MR 2 SDWIS / WA5362675 / 2984
2011 Benzene MR 2 SDWIS / WA5362675 / 2990
2011 Toluene MR 2 SDWIS / WA5362675 / 2991
2011 Ethylbenzene MR 2 SDWIS / WA5362675 / 2992
2011 1,2,4-Trichlorobenzene MR 2 SDWIS / WA5362675 / 2378
2011 DICHLOROMETHANE MR 2 SDWIS / WA5362675 / 2964
2011 p-Dichlorobenzene MR 2 SDWIS / WA5362675 / 2969

How Oak Park Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Oak Park Washington avg Federal benchmark
Total violations 61 69 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 2 4.5 Indicates a contaminant exceeded a federal MCL
PFAS detection None 39.7% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 695 2,137 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 4,557 regulated public water systems in Washington.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Oak Park water safe to drink? ▼
Oak Park (PWS ID: WA5362675) has 61 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 695 people using Groundwater sources.
How many people does Oak Park serve? ▼
Oak Park serves 695 people in Shelton, Washington. It is a Private-owned system using Groundwater water sources with 227 service connections.
What type of violations does Oak Park have? ▼
Oak Park has 61 total violations: 2 health-based violations (MCL exceedances or treatment failures), 55 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Oak Park water? ▼
No PFAS testing data is available for Oak Park under the EPA's UCMR5 monitoring program.
What water source does Oak Park use? ▼
Oak Park uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

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

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.