Public water system · WA5387140
ActiveTamoshan
At a glance
Tamoshan (PWSID WA5387140) is an active community water system in Thurston County, Washington. It reports serving 260 people through 94 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 8 are health-based, and the most recent began in June 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
260
Service connections
94
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Tamoshan compare with other water systems in Thurston County?
By EPA's size categories, Tamoshan is a very small system (500 people or fewer). Thurston County has 322 active public water systems. Its population served is well below the county average of 1,233 people per system, and accounts for less than 0.1% of the 397,060 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 Tamoshan is well below 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. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 4,370 Washington systems (93%) list groundwater as their primary source.
Who owns and regulates Tamoshan?
EPA lists Tamoshan 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. 73 of the 322 active systems in Thurston County (23%) are also owned by a local government.
Does Tamoshan have drinking water violations?
Of the 12 most recent violations in EPA's records, 8 are health-based, and the most recent began in June 2025. The violations listed here began between October 2018 and June 2025. By type: 8 contaminant level above the legal limit, 3 monitoring and 1 monitoring and reporting. The contaminant or rule involved most often is Haloacetic acids (HAA5) (8 of them). EPA lists 12 as resolved. 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 |
|---|---|---|---|---|
| 2025-06-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2023-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2023-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2022-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2022-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2022-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2022-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2021-12-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2021-11-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2021-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2021-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Resolved |
| 2018-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
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.
Tamoshan: frequently asked questions
Who runs Tamoshan?
Tamoshan (PWSID WA5387140) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does Tamoshan serve?
Tamoshan reports serving 260 people through 94 service connections in Thurston County, Washington.
Where does Tamoshan get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Tamoshan have any drinking water violations?
Of the 12 most recent violations in EPA's records, 8 are health-based, and the most recent began in June 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 Tamoshan'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, 8 are health-based, and the most recent began in June 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 Tamoshan's water quality report?
As a community water system, Tamoshan 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 Thurston County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Olympia City of | Thurston | 126,966 | Community | Groundwater |
| Lacey Water Department | Thurston | 105,178 | Community | Groundwater |
| Tumwater City of | Thurston | 51,802 | Community | Groundwater |
| Yelm City of | Thurston | 17,355 | Community | Groundwater |
| Tanglewilde Thompson Place 600 | Thurston | 7,900 | Community | Groundwater |
| Pattison 500 | Thurston | 4,643 | 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, “Tamoshan, PWSID WA5387140, Washington”, https://aquacensus.com/water-systems/washington/tamoshan-wa5387140 (data as of October 1, 2026).