Public water system · WA5307731
ActiveMossyrock Park Power House
At a glance
Mossyrock Park Power House (PWSID WA5307731) is an active transient non-community water system in Lewis County, Washington. It reports serving 832 people through 112 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 11 violations for this system; 9 are health-based, and the most recent began in August 2005.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
832
Service connections
112
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Mossyrock Park Power House compare with other water systems in Lewis County?
By EPA's size categories, Mossyrock Park Power House is a small system (501 to 3,300 people). Lewis County has 166 active public water systems. Its population served is about 55% above the county average of 537 people per system, and accounts for 0.9% of the 89,186 people reported by systems filed under the county. Across Washington, the 4,705 active systems average 2,172 people each. Nationally, the average active transient non-community water system reports serving 144 people, so Mossyrock Park Power House is about 5.8 times that figure.
What does “transient non-community water system” mean?
A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. Washington has 1,913 active transient non-community water systems, 41% 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 Mossyrock Park Power House?
EPA lists Mossyrock Park Power House 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. 37 of the 166 active systems in Lewis County (22%) are also owned by a local government.
Does Mossyrock Park Power House have drinking water violations?
EPA's records list 11 violations for this system; 9 are health-based, and the most recent began in August 2005. The violations listed here began between November 1991 and August 2005. By type: 9 contaminant level above the legal limit and 2 monitoring and reporting. The contaminant or rule involved most often is Total coliform bacteria (TCR) (11 of them). EPA lists 11 as archived. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2005-08-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 2005-06-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 2003-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 2003-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1995-11-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1995-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1994-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1993-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1993-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1991-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
All 11 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.
Mossyrock Park Power House: frequently asked questions
Who runs Mossyrock Park Power House?
Mossyrock Park Power House (PWSID WA5307731) is a transient non-community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does Mossyrock Park Power House serve?
Mossyrock Park Power House reports serving 832 people through 112 service connections in Lewis County, Washington.
Where does Mossyrock Park Power House 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 Mossyrock Park Power House have any drinking water violations?
EPA's records list 11 violations for this system; 9 are health-based, and the most recent began in August 2005. 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 Mossyrock Park Power House'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. EPA's records list 11 violations for this system; 9 are health-based, and the most recent began in August 2005. For current results, consult EPA ECHO, or the WA state drinking water program.
Where can I find Mossyrock Park Power House's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Mossyrock Park Power House is a transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in Lewis County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Centralia Public Works - Water | Lewis | 28,164 | Community | Groundwater |
| Chehalis Water Department | Lewis | 11,718 | Community | Surface water |
| Winlock City of | Lewis | 3,502 | Community | Groundwater |
| Napavine City of | Lewis | 3,095 | Community | Groundwater |
| Boistfort Valley | Lewis | 2,389 | Community | Surface water |
| Morton City of | Lewis | 2,147 | Community | Surface water |
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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, “Mossyrock Park Power House, PWSID WA5307731, Washington”, https://aquacensus.com/water-systems/washington/mossyrock-park-power-house-wa5307731 (data as of October 1, 2026).