Public water system · OR4190178
ActiveUsace Mcnary Dam
At a glance
Usace Mcnary Dam (PWSID OR4190178) is an active non-transient non-community water system in Umatilla County, Oregon. It reports serving 120 people through 6 service connections. Its primary water source is groundwater, and EPA lists it as owned by the federal 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
120
Service connections
6
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Usace Mcnary Dam compare with other water systems in Umatilla County?
By EPA's size categories, Usace Mcnary Dam is a very small system (500 people or fewer). Umatilla County has 66 active public water systems. Its population served is well below the county average of 1,041 people per system, and accounts for 0.2% of the 68,687 people reported by systems filed under the county. Across Oregon, the 2,536 active systems average 1,587 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Usace Mcnary Dam is well below that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. Oregon has 346 active non-transient non-community water systems, 14% 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 Usace Mcnary Dam?
EPA lists Usace Mcnary Dam as owned by the federal 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. 2 of the 66 active systems in Umatilla County (3%) are also owned by the federal government.
Does Usace Mcnary Dam 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 2005 and January 2025. By type: 11 monitoring and reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Coliphage (4 of them). EPA lists 11 as resolved and 1 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 |
|---|---|---|---|---|
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Archived |
| 2023-09-01 | Monitoring and reportingFailure to Conduct Assessment Monitoring · code 19 | Coliphagecode 3028 | No | Resolved |
| 2023-09-01 | Monitoring and reportingFailure to Conduct Assessment Monitoring · code 19 | Coliphagecode 3028 | No | Resolved |
| 2023-07-01 | Monitoring and reportingFailure to Conduct Assessment Monitoring · code 19 | Coliphagecode 3028 | No | Resolved |
| 2023-07-01 | Monitoring and reportingFailure to Conduct Assessment Monitoring · code 19 | Coliphagecode 3028 | No | Resolved |
| 2015-11-03 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2015-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2014-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Benzo(a)pyrenecode 2306 | No | Resolved |
| 2006-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2006-01-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2005-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Glyphosatecode 2034 | No | Resolved |
| 2005-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Toxaphenecode 2020 | 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.
Usace Mcnary Dam: frequently asked questions
Who runs Usace Mcnary Dam?
Usace Mcnary Dam (PWSID OR4190178) is a non-transient non-community water system owned by the federal government. It is regulated by the OR state drinking water program.
How many people does Usace Mcnary Dam serve?
Usace Mcnary Dam reports serving 120 people through 6 service connections in Umatilla County, Oregon.
Where does Usace Mcnary Dam 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 Usace Mcnary Dam 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 Usace Mcnary Dam'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 January 2025. For current results, consult EPA ECHO, or the OR state drinking water program.
Where can I find Usace Mcnary Dam's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Usace Mcnary Dam is a non-transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in Umatilla County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Hermiston, City of | Umatilla | 20,000 | Community | Surface water |
| Pendleton, City of | Umatilla | 16,996 | Community | Surface water |
| Umatilla, City of | Umatilla | 8,256 | Community | Groundwater |
| Milton-Freewater, City of | Umatilla | 7,145 | Community | Groundwater |
| Stanfield, City of | Umatilla | 2,115 | Community | Groundwater |
| Pilot Rock, City of | Umatilla | 1,326 | 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, “Usace Mcnary Dam, PWSID OR4190178, Oregon”, https://aquacensus.com/water-systems/oregon/usace-mcnary-dam-or4190178 (data as of October 1, 2026).