Public water system · WA5397744
ActiveWinthrop Koa
At a glance
Winthrop Koa (PWSID WA5397744) is an active transient non-community water system in Okanogan County, Montana. It reports serving 77 people through 79 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in December 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
77
Service connections
79
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Winthrop Koa compare with other water systems in Okanogan County?
By EPA's size categories, Winthrop Koa is a very small system (500 people or fewer). Okanogan County has 1 active public water system, and Winthrop Koa is the largest of them by population served. Its population served is roughly in line with the county average of 77 people per system, and accounts for 100% of the 77 people reported by systems filed under the county. Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active transient non-community water system reports serving 144 people, so Winthrop Koa is about half of that figure.
What does “transient non-community water system” mean?
A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. Montana has 1,206 active transient non-community water systems, 51% of the state's 2,378 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,994 Montana systems (84%) list groundwater as their primary source.
Who owns and regulates Winthrop Koa?
EPA lists Winthrop Koa as privately owned. 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. 1 of the 1 active systems in Okanogan County (100%) are also privately owned.
Does Winthrop Koa have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in December 2025. The violations listed here began between August 1992 and December 2025. By type: 10 monitoring and reporting and 2 monitoring. The contaminant or rule involved most often is Total coliform bacteria (TCR) (9 of them). EPA lists 10 as archived and 2 as resolved. 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. 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 |
|---|---|---|---|---|
| 2025-12-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2025-06-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Archived |
| 2013-04-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2006-09-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 2004-09-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 2000-08-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 2000-04-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1999-06-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1999-04-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1997-07-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-08-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
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.
Winthrop Koa: frequently asked questions
Who runs Winthrop Koa?
Winthrop Koa (PWSID WA5397744) is a transient non-community water system privately owned. It is regulated by the WA state drinking water program.
How many people does Winthrop Koa serve?
Winthrop Koa reports serving 77 people through 79 service connections in Okanogan County, Montana.
Where does Winthrop Koa 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 Winthrop Koa 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 December 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 Winthrop Koa'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 December 2025. For current results, consult EPA ECHO, or the WA state drinking water program.
Where can I find Winthrop Koa's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Winthrop Koa is a 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.
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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, “Winthrop Koa, PWSID WA5397744, Montana”, https://aquacensus.com/water-systems/montana/winthrop-koa-wa5397744 (data as of October 1, 2026).