Public water system · OR4100356
ActiveGrass Valley Water System
At a glance
Grass Valley Water System (PWSID OR4100356) is an active community water system in Sherman County, Oregon. It reports serving 184 people through 92 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, 2 are health-based, and the most recent began in February 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
184
Service connections
92
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Grass Valley Water System compare with other water systems in Sherman County?
By EPA's size categories, Grass Valley Water System is a very small system (500 people or fewer). Sherman County has 12 active public water systems. Its population served is about 40% below the county average of 309 people per system, and accounts for 5% of the 3,709 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 Grass Valley Water System 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 Grass Valley Water System?
EPA lists Grass Valley Water System 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. 6 of the 12 active systems in Sherman County (50%) are also owned by a local government.
Does Grass Valley Water System have drinking water violations?
Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in February 2026. The violations listed here began between July 2004 and February 2026. By type: 8 monitoring and reporting, 2 contaminant level above the legal limit, 1 monitoring and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (5 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 |
|---|---|---|---|---|
| 2026-02-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2011-09-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2009-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2007-07-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2007-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2005-05-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2005-01-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2005-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2004-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2004-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | 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.
Grass Valley Water System: frequently asked questions
Who runs Grass Valley Water System?
Grass Valley Water System (PWSID OR4100356) is a community water system owned by a local government. It is regulated by the OR state drinking water program.
How many people does Grass Valley Water System serve?
Grass Valley Water System reports serving 184 people through 92 service connections in Sherman County, Oregon.
Where does Grass Valley Water System 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 Grass Valley Water System have any drinking water violations?
Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in February 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 Grass Valley Water System'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, 2 are health-based, and the most recent began in February 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 Grass Valley Water System's water quality report?
As a community water system, Grass Valley Water System 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 Sherman County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Biggs Service District | Sherman | 1,600 | Non-transient non-community | Groundwater |
| Wasco, City of | Sherman | 460 | Community | Groundwater |
| Moro, City of | Sherman | 350 | Community | Groundwater |
| Rufus Public Works | Sherman | 270 | Community | Groundwater |
| Sherman County School | Sherman | 240 | Non-transient non-community | Groundwater |
| Oprd Deschutes River Rec Area | Sherman | 200 | 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, “Grass Valley Water System, PWSID OR4100356, Oregon”, https://aquacensus.com/water-systems/oregon/grass-valley-water-system-or4100356 (data as of October 1, 2026).