Public water system · WA5352000
ActiveMattawa City of
At a glance
City of Mattawa (PWSID WA5352000) is an active community water system in Grant County, Washington. It reports serving 5,370 people through 1,026 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, one is health-based, and the most recent began in June 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
5,370
Service connections
1,026
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does City of Mattawa compare with other water systems in Grant County?
By EPA's size categories, City of Mattawa is a medium system (3,301 to 10,000 people). Grant County has 265 active public water systems, and City of Mattawa is the 5th-largest of them by population served. Its population served is about 9.9 times the county average of 543 people per system, and accounts for 3.7% 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 community water system reports serving 6,703 people, so City of Mattawa is about 20% 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 City of Mattawa?
EPA lists City of Mattawa 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. 26 of the 265 active systems in Grant County (9.8%) are also owned by a local government.
Does City of Mattawa have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in June 2024. The violations listed here began between January 2014 and June 2024. By type: 9 monitoring and reporting, 2 public notice, recordkeeping or other and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Consumer Confidence Rule (2 of them). EPA lists 7 as resolved and 5 as archived. 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. 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 |
|---|---|---|---|---|
| 2024-06-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, E. coli (RTCR) · code 1A | Revised Total Coliform Rulecode 8000 | Yes | Resolved |
| 2023-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2016-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Cadmiumcode 1015 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Vinyl chloridecode 2976 | No | Archived |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Berylliumcode 1075 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Chlorobenzenecode 2989 | No | Archived |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | p-Dichlorobenzenecode 2969 | No | Archived |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Seleniumcode 1045 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1-Dichloroethylenecode 2977 | No | Archived |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Tetrachloroethylenecode 2987 | No | Archived |
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.
City of Mattawa: frequently asked questions
Who runs City of Mattawa?
City of Mattawa (PWSID WA5352000) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does City of Mattawa serve?
City of Mattawa reports serving 5,370 people through 1,026 service connections in Grant County, Washington.
Where does City of Mattawa 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 City of Mattawa have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in June 2024. 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 City of Mattawa'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, one is health-based, and the most recent began in June 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the WA state drinking water program.
Where can I find City of Mattawa's water quality report?
As a community water system, City of Mattawa 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 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 |
| Sun Lakes State Park | Grant | 4,858 | Transient non-community | Groundwater |
| Warden City of | Grant | 4,674 | 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, “Mattawa City of, PWSID WA5352000, Washington”, https://aquacensus.com/water-systems/washington/mattawa-city-of-wa5352000 (data as of October 1, 2026).