Public water system · OR4100807
ActiveSeneca, City of
At a glance
City of Seneca (PWSID OR4100807) is an active community water system in Grant County, Oregon. It reports serving 200 people through 112 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, none is health-based, and the most recent began in October 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
200
Service connections
112
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does City of Seneca compare with other water systems in Grant County?
By EPA's size categories, City of Seneca is a very small system (500 people or fewer). Grant County has 15 active public water systems, and City of Seneca is the 6th-largest of them by population served. Its population served is about 41% below the county average of 339 people per system, and accounts for 3.9% of the 5,090 people reported by systems filed under the county. Across Oregon, the 2,536 active systems average 1,587 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Seneca 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. Oregon has 940 active community water systems, 37% of the state's 2,536 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 2,175 Oregon systems (86%) list groundwater as their primary source.
Who owns and regulates City of Seneca?
EPA lists City of Seneca as owned by a local government. The OR state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 8 of the 15 active systems in Grant County (53%) are also owned by a local government.
Does City of Seneca have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in October 2025. The violations listed here began between January 2018 and October 2025. By type: 6 monitoring, 3 public notice, recordkeeping or other and 3 monitoring and reporting. The contaminant or rule involved most often is Revised Total Coliform Rule (6 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 |
|---|---|---|---|---|
| 2025-10-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2024-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2023-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2023-10-01 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2023-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2022-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2019-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2019-04-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2019-01-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2018-12-17 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2018-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2018-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | 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.
City of Seneca: frequently asked questions
Who runs City of Seneca?
City of Seneca (PWSID OR4100807) is a community water system owned by a local government. It is regulated by the OR state drinking water program.
How many people does City of Seneca serve?
City of Seneca reports serving 200 people through 112 service connections in Grant County, Oregon.
Where does City of Seneca 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 Seneca have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in October 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 City of Seneca'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, none is health-based, and the most recent began in October 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the OR state drinking water program.
Where can I find City of Seneca's water quality report?
As a community water system, City of Seneca 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 |
|---|---|---|---|---|
| John Day, City of | Grant | 1,617 | Community | Groundwater |
| Prairie City | Grant | 841 | Community | Groundwater under influence of surface water |
| Canyon City Water Department | Grant | 666 | Community | Groundwater under influence of surface water |
| Mount Vernon, City of | Grant | 510 | Community | Groundwater |
| Oprd Clyde Holliday Wayside | Grant | 450 | Transient non-community | Groundwater |
| Long Creek, City of | Grant | 173 | 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, “Seneca, City of, PWSID OR4100807, Oregon”, https://aquacensus.com/water-systems/oregon/seneca-city-of-or4100807 (data as of October 1, 2026).