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Community Water System · PWS WA5323294

Emerald Lake

Shelton, Washington 98584-5034 - drinking water served from groundwater sources to 331 people, tracked in EPA SDWIS and UCMR5.

331
People served
16
EPA violations
4
Health-based
No PFAS
UCMR5 result

The verdict

EPA records 16 drinking-water violations at Emerald Lake, 25% of them health-based - below the Washington per-system average.

16
Total EPA violations on record
25%
Health-based (MCL / treatment failure)
331
People served by this system
0
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Emerald Lake

Emerald Lake is a private-owned community water system that delivers drinking water to 331 residents in Shelton, Washington (Mason County) through 139 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 16 total violations for this system , of which 4 (25%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 9 monitoring and reporting violations are on file. The most recent violation on record dates to 2019.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 6 violations (MR). This system was sampled under EPA's UCMR5 PFAS monitoring program and no PFAS compounds were detected above the minimum reporting level.

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%).

Emerald Lake's 16 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
331
Total Violations
16
Health-Based Violations
4
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
139
County
Mason
School/Daycare
No
MCL Violations
4
Monitoring Violations
9
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 6 1993
Coliform (TCR) MCL 4 1993
Lead and Copper Rule MR 2 2019
Gross Alpha, Excl. Radon and U MR 1 1979

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 58 samples detected PFAS.

Contaminant Date Result MRL Status
PFTA 12/27/2023 <8.00 ppt 8.00 ppt Not Detected
4:2 FTS 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
ADONA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 12/27/2023 <5.00 ppt 5.00 ppt Not Detected
PFBA 12/27/2023 <5.00 ppt 5.00 ppt Not Detected
6:2 FTS 12/27/2023 <5.00 ppt 5.00 ppt Not Detected
8:2 FTS 12/27/2023 <5.00 ppt 5.00 ppt Not Detected
PFMPA 12/27/2023 <4.00 ppt 4.00 ppt Not Detected
PFPeS 12/27/2023 <4.00 ppt 4.00 ppt Not Detected
PFHpS 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
9Cl-PF3ONS 12/27/2023 <2.00 ppt 2.00 ppt Not Detected
PFTrDA 12/27/2023 <7.00 ppt 7.00 ppt Not Detected
PFNA 12/27/2023 <4.00 ppt 4.00 ppt Not Detected
PFBS 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFPeA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
11Cl-PF3OUdS 12/27/2023 <5.00 ppt 5.00 ppt Not Detected
PFHxA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFDoA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFDA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFOS 12/27/2023 <4.00 ppt 4.00 ppt Not Detected
PFHxS 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFHpA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFUnA 12/27/2023 <2.00 ppt 2.00 ppt Not Detected
NMeFOSAA 12/27/2023 <6.00 ppt 6.00 ppt Not Detected
NEtFOSAA 12/27/2023 <5.00 ppt 5.00 ppt Not Detected
PFMBA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
PFEESA 12/27/2023 <3.00 ppt 3.00 ppt Not Detected
NFDHA 12/27/2023 <20.00 ppt 20.00 ppt Not Detected
PFOA 12/27/2023 <4.00 ppt 4.00 ppt Not Detected
PFPeA 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
9Cl-PF3ONS 10/23/2023 <2.00 ppt 2.00 ppt Not Detected
ADONA 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 10/23/2023 <5.00 ppt 5.00 ppt Not Detected
PFBA 10/23/2023 <5.00 ppt 5.00 ppt Not Detected
6:2 FTS 10/23/2023 <5.00 ppt 5.00 ppt Not Detected
4:2 FTS 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
11Cl-PF3OUdS 10/23/2023 <5.00 ppt 5.00 ppt Not Detected
PFMPA 10/23/2023 <4.00 ppt 4.00 ppt Not Detected
PFMBA 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
NMeFOSAA 10/23/2023 <6.00 ppt 6.00 ppt Not Detected
PFEESA 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
PFHpS 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
PFTA 10/23/2023 <8.00 ppt 8.00 ppt Not Detected
PFTrDA 10/23/2023 <7.00 ppt 7.00 ppt Not Detected
NEtFOSAA 10/23/2023 <5.00 ppt 5.00 ppt Not Detected
8:2 FTS 10/23/2023 <5.00 ppt 5.00 ppt Not Detected
PFHpA 10/23/2023 <3.00 ppt 3.00 ppt Not Detected
PFUnA 10/23/2023 <2.00 ppt 2.00 ppt Not Detected
PFPeS 10/23/2023 <4.00 ppt 4.00 ppt Not Detected
PFBS 10/23/2023 <3.00 ppt 3.00 ppt Not Detected

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 Emerald Lake.

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 WA5323294 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 Emerald Lake 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
2019 Lead and Copper Rule MR 2 SDWIS / WA5323294 / 5000
1993 Coliform (TCR) MR 6 SDWIS / WA5323294 / 3100
1993 Coliform (TCR) MCL 4 SDWIS / WA5323294 / 3100
1979 Gross Alpha, Excl. Radon and U MR 1 SDWIS / WA5323294 / 4000

How Emerald Lake Compares

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

Metric Emerald Lake Washington avg Federal benchmark
Total violations 16 69 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 4 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 331 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 Emerald Lake water safe to drink? ▼
Emerald Lake (PWS ID: WA5323294) has 16 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 331 people using Groundwater sources.
How many people does Emerald Lake serve? ▼
Emerald Lake serves 331 people in Shelton, Washington. It is a Private-owned system using Groundwater water sources with 139 service connections.
What type of violations does Emerald Lake have? ▼
Emerald Lake has 16 total violations: 4 health-based violations (MCL exceedances or treatment failures), 9 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Emerald Lake water? ▼
No. Emerald Lake was tested for PFAS under the EPA's UCMR5 monitoring program and no PFAS contamination was detected.
What water source does Emerald Lake use? ▼
Emerald Lake 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. PFAS data from EPA UCMR5 monitoring program (2023-2025). 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.