Public water system · OR4100540
ActiveMonroe, City of
At a glance
City of Monroe (PWSID OR4100540) is an active community water system in Benton County, Oregon. It reports serving 723 people through 343 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in January 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
723
Service connections
343
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does City of Monroe compare with other water systems in Benton County?
By EPA's size categories, City of Monroe is a small system (501 to 3,300 people). Benton County has 51 active public water systems, and City of Monroe is the 4th-largest of them by population served. Its population served is about half of the county average of 1,430 people per system, and accounts for 1% of the 72,904 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 Monroe 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. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 211 Oregon systems (8.3%) list surface water as their primary source.
Who owns and regulates City of Monroe?
EPA lists City of Monroe 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. 17 of the 51 active systems in Benton County (33%) are also owned by a local government.
Does City of Monroe have drinking water violations?
Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in January 2026. The violations listed here began between December 2023 and January 2026. By type: 6 monitoring and reporting, 4 contaminant level above the legal limit and 2 public notice, recordkeeping or other. The contaminant or rule involved most often is Surface Water Treatment Rule (5 of them). EPA lists 7 as resolved, 4 as archived and 1 as unaddressed. 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. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2026-01-11 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2026-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-10-01 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Unaddressed |
| 2025-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2024-01-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2024-01-01 | Monitoring and reportingInitial, Follow-up, or Routine Source Water M/R · code 56 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2023-12-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2023-12-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | 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 Monroe: frequently asked questions
Who runs City of Monroe?
City of Monroe (PWSID OR4100540) 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 Monroe serve?
City of Monroe reports serving 723 people through 343 service connections in Benton County, Oregon.
Where does City of Monroe get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does City of Monroe have any drinking water violations?
Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in January 2026. 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 Monroe'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, 4 are health-based, and the most recent began in January 2026. 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 Monroe's water quality report?
As a community water system, City of Monroe 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 Benton County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Corvallis, City of | Benton | 61,468 | Community | Surface water |
| Philomath Public Works | Benton | 4,670 | Community | Surface water |
| Adair Village Water System | Benton | 875 | Community | Surface water |
| Knoll Terrace Park | Benton | 452 | Community | Groundwater |
| Vineyard Mountain Water | Benton | 325 | Community | Groundwater |
| Lineage Logistics | Benton | 290 | Non-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, “Monroe, City of, PWSID OR4100540, Oregon”, https://aquacensus.com/water-systems/oregon/monroe-city-of-or4100540 (data as of October 1, 2026).