Public water system · CA0600005

Active

Colusa Co. Service Area #2-Stonyford

At a glance

Colusa Co. Service Area #2-Stonyford (PWSID CA0600005) is an active community water system in Colusa County, California. It reports serving 250 people through 57 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 8 violations for this system; 1 is health-based, and the most recent began in December 2021.

Dataset updated October 2026 . Source: EPA SDWIS/ECHO public records.

Population served

250

Service connections

Primary source

Groundwater

System type

CWS

Community water system

System record

PWSIDCA0600005

System typeCommunity water system

Activity statusActive

Population served250

Service connections57

Primary water sourceGroundwater

Owner typeLocal government

Primacy agencyCA state drinking water program

City served—

StateCalifornia

ZIP—

CountyColusa County

How does Colusa Co. Service Area #2-Stonyford compare with other water systems in Colusa County?

By EPA's size categories, Colusa Co. Service Area #2-Stonyford is a very small system (500 people or fewer). Colusa County has 29 active public water systems. Its population served is well below the county average of 1,211 people per system, and accounts for 0.7% of the 35,121 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 Colusa Co. Service Area #2-Stonyford 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. California has 2,997 active community water systems, 40% of the state's 7,479 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 6,179 California systems (83%) list groundwater as their primary source.

Who owns and regulates Colusa Co. Service Area #2-Stonyford?

EPA lists Colusa Co. Service Area #2-Stonyford 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. 7 of the 29 active systems in Colusa County (24%) are also owned by a local government.

Does Colusa Co. Service Area #2-Stonyford have drinking water violations?

EPA's records list 8 violations for this system; 1 is health-based, and the most recent began in December 2021. The violations listed here began between October 1980 and December 2021. By type: 5 monitoring and reporting, 1 monitoring, 1 public notice, recordkeeping or other and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Gross alpha (excluding radon and uranium) (2 of them). EPA lists 6 as resolved and 2 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
2021-12-01	Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36	Surface Water Treatment Rulecode 0200	No	Resolved
2021-07-01	MonitoringMonitoring, Additional Routine (RTCR) · code 3B	Revised Total Coliform Rulecode 8000	No	Resolved
2019-07-01	Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71	Consumer Confidence Rulecode 7000	No	Resolved
2015-01-01	Monitoring and reportingMonitoring and Reporting (DBP) · code 27	Haloacetic acids (HAA5)code 2456	No	Resolved
1995-12-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22	Total coliform bacteria (TCR)code 3100	Yes	Resolved
1993-07-01	Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51	Lead and Copper Rulecode 5000	No	Resolved
1981-10-01	Monitoring and reportingMonitoring, Regular · code 03	Gross alpha (excluding radon and uranium)code 4000	No	Archived
1980-10-30	Monitoring and reportingMonitoring, Regular · code 03	Gross alpha (excluding radon and uranium)code 4000	No	Archived

All 8 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.

Colusa Co. Service Area #2-Stonyford: frequently asked questions

Who runs Colusa Co. Service Area #2-Stonyford?

Colusa Co. Service Area #2-Stonyford (PWSID CA0600005) is a community water system owned by a local government. It is regulated by the CA state drinking water program.

How many people does Colusa Co. Service Area #2-Stonyford serve?

Colusa Co. Service Area #2-Stonyford reports serving 250 people through 57 service connections in Colusa County, California.

Where does Colusa Co. Service Area #2-Stonyford 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 Colusa Co. Service Area #2-Stonyford have any drinking water violations?

EPA's records list 8 violations for this system; 1 is health-based, and the most recent began in December 2021. 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 Colusa Co. Service Area #2-Stonyford'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 8 violations for this system; 1 is health-based, and the most recent began in December 2021. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.

Where can I find Colusa Co. Service Area #2-Stonyford's water quality report?

As a community water system, Colusa Co. Service Area #2-Stonyford 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 Colusa County

Water system	County	Population served	Type	Source
Caltrans-Maxwell Reststops	Colusa	15,000	Transient non-community	Groundwater
City of Colusa	Colusa	6,447	Community	Groundwater
City of Williams	Colusa	5,538	Community	Groundwater
Arbuckle Public Utility District	Colusa	2,778	Community	Groundwater
Maxwell Public Utility District	Colusa	1,175	Community	Groundwater
Colusa Industrial Properties	Colusa	533	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, “Colusa Co. Service Area #2-Stonyford, PWSID CA0600005, California”, https://aquacensus.com/water-systems/california/colusa-co-service-area-2-stonyford-ca0600005 (data as of October 1, 2026).