Public water system · WA5306029
ActiveYak Co - Terrace Heights
At a glance
Yak Co - Terrace Heights (PWSID WA5306029) is an active community water system in Yakima County, Washington. It reports serving 8,410 people through 2,725 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 January 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
8,410
Service connections
2,725
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Yak Co - Terrace Heights compare with other water systems in Yakima County?
By EPA's size categories, Yak Co - Terrace Heights is a medium system (3,301 to 10,000 people). Yakima County has 217 active public water systems. Its population served is about 6.8 times the county average of 1,230 people per system, and accounts for 3.2% of the 266,832 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 Yak Co - Terrace Heights is about 25% above 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 Yak Co - Terrace Heights?
EPA lists Yak Co - Terrace Heights 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. 21 of the 217 active systems in Yakima County (9.7%) are also owned by a local government.
Does Yak Co - Terrace Heights have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2025. The violations listed here began between January 2020 and January 2025. By type: 10 monitoring and reporting, 1 contaminant level above the legal limit and 1 monitoring. The contaminant or rule involved most often is Nitrate (3 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 |
|---|---|---|---|---|
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2023-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, E. coli (RTCR) · code 1A | Revised Total Coliform Rulecode 8000 | Yes | Resolved |
| 2022-10-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,2-Trichloroethanecode 2985 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,1-Trichloroethanecode 2981 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | p-Dichlorobenzenecode 2969 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Tetrachloroethylenecode 2987 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Benzenecode 2990 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2,4-Trichlorobenzenecode 2378 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | cis-1,2-Dichloroethylenecode 2380 | 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.
Yak Co - Terrace Heights: frequently asked questions
Who runs Yak Co - Terrace Heights?
Yak Co - Terrace Heights (PWSID WA5306029) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does Yak Co - Terrace Heights serve?
Yak Co - Terrace Heights reports serving 8,410 people through 2,725 service connections in Yakima County, Washington.
Where does Yak Co - Terrace Heights 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 Yak Co - Terrace Heights 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 January 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 Yak Co - Terrace Heights' 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 January 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 Yak Co - Terrace Heights' water quality report?
As a community water system, Yak Co - Terrace Heights 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 Yakima County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Yakima Water Division City of | Yakima | 112,858 | Community | Surface water |
| Nob Hill Water Association | Yakima | 38,050 | Community | Groundwater |
| Sunnyside City of | Yakima | 17,194 | Community | Groundwater |
| Grandview City of | Yakima | 11,010 | Community | Groundwater |
| Selah City of | Yakima | 9,331 | Community | Groundwater |
| Toppenish Water Department | Yakima | 8,950 | 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, “Yak Co - Terrace Heights, PWSID WA5306029, Washington”, https://aquacensus.com/water-systems/washington/yak-co-terrace-heights-wa5306029 (data as of October 1, 2026).