Public water system · WA53AC100
ActiveAmt - Mattawa Ranch
At a glance
Amt - Mattawa Ranch (PWSID WA53AC100) is an active transient non-community water system in Grant County, Washington. It reports serving 95 people through 8 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2010.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
95
Service connections
8
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Amt - Mattawa Ranch compare with other water systems in Grant County?
By EPA's size categories, Amt - Mattawa Ranch is a very small system (500 people or fewer). Grant County has 265 active public water systems. Its population served is well below the county average of 543 people per system, and accounts for less than 0.1% of the 143,944 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 Amt - Mattawa Ranch is about 34% below 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 Amt - Mattawa Ranch?
EPA lists Amt - Mattawa Ranch as privately owned. 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. 227 of the 265 active systems in Grant County (86%) are also privately owned.
Does Amt - Mattawa Ranch have drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2010. By type: 1 monitoring and reporting. The contaminant or rule involved is Total coliform bacteria (TCR). EPA lists 1 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 |
|---|---|---|---|---|
| 2010-10-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
The one violation in EPA's records.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.
Amt - Mattawa Ranch: frequently asked questions
Who runs Amt - Mattawa Ranch?
Amt - Mattawa Ranch (PWSID WA53AC100) is a transient non-community water system privately owned. It is regulated by the WA state drinking water program.
How many people does Amt - Mattawa Ranch serve?
Amt - Mattawa Ranch reports serving 95 people through 8 service connections in Grant County, Washington.
Where does Amt - Mattawa Ranch 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 Amt - Mattawa Ranch have any drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2010. 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 Amt - Mattawa Ranch'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 one violation for this system; it is not health-based, and the most recent began in October 2010. For current results, consult EPA ECHO, or the WA state drinking water program.
Where can I find Amt - Mattawa Ranch's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Amt - Mattawa Ranch 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 Grant County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Moses Lake City of | Grant | 32,428 | Community | Groundwater |
| Gorge Amphitheatre | Grant | 25,119 | Transient non-community | Groundwater |
| Ephrata Water Department | Grant | 8,718 | Community | Groundwater |
| Quincy Water Department City of | Grant | 8,415 | Community | Groundwater |
| Mattawa City of | Grant | 5,370 | Community | Groundwater |
| Sun Lakes State Park | Grant | 4,858 | 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, “Amt - Mattawa Ranch, PWSID WA53AC100, Washington”, https://aquacensus.com/water-systems/washington/amt-mattawa-ranch-wa53ac100 (data as of October 1, 2026).