Public water system · CA2310005
ActiveWillow County Water District
At a glance
Willow County Water District (PWSID CA2310005) is an active community water system in Mendocino County, California. It reports serving 3,797 people through 1,079 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 3 violations for this system; none is health-based, and the most recent began in August 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
3,797
Service connections
1,079
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Willow County Water District compare with other water systems in Mendocino County?
By EPA's size categories, Willow County Water District is a medium system (3,301 to 10,000 people). Mendocino County has 144 active public water systems, and Willow County Water District is the 6th-largest of them by population served. Its population served is about 6.6 times the county average of 576 people per system, and accounts for 4.6% of the 82,868 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active community water system reports serving 6,703 people, so Willow County Water District is about 43% 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. California has 2,997 active community water systems, 40% of the state's 7,479 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 506 California systems (6.8%) list purchased surface water as their primary source.
Who owns and regulates Willow County Water District?
EPA lists Willow County Water District as owned by a local government. The CA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 26 of the 144 active systems in Mendocino County (18%) are also owned by a local government.
Does Willow County Water District have drinking water violations?
EPA's records list 3 violations for this system; none is health-based, and the most recent began in August 2024. The violations listed here began between October 1988 and August 2024. By type: 1 monitoring, 1 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminants or rules involved are Revised Total Coliform Rule and E. coli. EPA lists 2 as archived and 1 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 |
|---|---|---|---|---|
| 2024-08-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2021-01-01 | Monitoring and reportingFailure to Conduct Assessment Monitoring · code 19 | E. colicode 3014 | No | Resolved |
| 1988-10-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
All 3 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.
Willow County Water District: frequently asked questions
Who runs Willow County Water District?
Willow County Water District (PWSID CA2310005) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Willow County Water District serve?
Willow County Water District reports serving 3,797 people through 1,079 service connections in Mendocino County, California.
Where does Willow County Water District get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Willow County Water District have any drinking water violations?
EPA's records list 3 violations for this system; none is health-based, and the most recent began in August 2024. 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 Willow County Water District'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. EPA's records list 3 violations for this system; none is health-based, and the most recent began in August 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Willow County Water District's water quality report?
As a community water system, Willow County Water District 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 Mendocino County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Ukiah, City of | Mendocino | 16,607 | Community | Surface water |
| Fort Bragg, City of | Mendocino | 6,919 | Community | Surface water |
| Willits, City of | Mendocino | 6,175 | Community | Surface water |
| Millview County Water District | Mendocino | 5,500 | Community | Surface water |
| Redwood Valley County Water District | Mendocino | 5,200 | Community | Surface water |
| Brooktrails Township Csd | Mendocino | 3,632 | Community | Surface water |
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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, “Willow County Water District, PWSID CA2310005, California”, https://aquacensus.com/water-systems/california/willow-county-water-district-ca2310005 (data as of October 1, 2026).