Public water system · CA4010001
ActiveCity of Arroyo Grande Utilities Division
At a glance
City of Arroyo Grande Utilities Division (PWSID CA4010001) is an active community water system in San Luis Obispo County, California. It reports serving 17,963 people through 6,694 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; 1 is health-based, and the most recent began in May 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
17,963
Service connections
6,694
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does City of Arroyo Grande Utilities Division compare with other water systems in San Luis Obispo County?
By EPA's size categories, City of Arroyo Grande Utilities Division is a large system (10,001 to 100,000 people). San Luis Obispo County has 171 active public water systems, and City of Arroyo Grande Utilities Division is the 5th-largest of them by population served. Its population served is about 8.8 times the county average of 2,038 people per system, and accounts for 5.2% of the 348,510 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 City of Arroyo Grande Utilities Division is about 168% above 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 City of Arroyo Grande Utilities Division?
EPA lists City of Arroyo Grande Utilities Division 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. 33 of the 171 active systems in San Luis Obispo County (19%) are also owned by a local government.
Does City of Arroyo Grande Utilities Division have drinking water violations?
EPA's records list 3 violations for this system; 1 is health-based, and the most recent began in May 2025. The violations listed here began between August 1996 and May 2025. By type: 1 monitoring, 1 monitoring and reporting and 1 contaminant level above the legal limit. The contaminants or rules involved are Revised Total Coliform Rule, Nitrate and Total trihalomethanes (TTHM). EPA lists 2 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 |
|---|---|---|---|---|
| 2025-05-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2012-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 1996-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
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.
City of Arroyo Grande Utilities Division: frequently asked questions
Who runs City of Arroyo Grande Utilities Division?
City of Arroyo Grande Utilities Division (PWSID CA4010001) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does City of Arroyo Grande Utilities Division serve?
City of Arroyo Grande Utilities Division reports serving 17,963 people through 6,694 service connections in San Luis Obispo County, California.
Where does City of Arroyo Grande Utilities Division 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 City of Arroyo Grande Utilities Division have any drinking water violations?
EPA's records list 3 violations for this system; 1 is health-based, and the most recent began in May 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 City of Arroyo Grande Utilities Division'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; 1 is health-based, and the most recent began in May 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find City of Arroyo Grande Utilities Division's water quality report?
As a community water system, City of Arroyo Grande Utilities Division 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 San Luis Obispo County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Santa Margarita Recreation Area | San Luis Obispo | 50,001 | Transient non-community | Groundwater |
| San Luis Obispo Water Department | San Luis Obispo | 47,788 | Community | Surface water |
| City of Paso Robles Water Division | San Luis Obispo | 31,176 | Community | Surface water |
| Atascadero Mutual Water Co | San Luis Obispo | 30,618 | Community | Groundwater |
| California Mens Colony | San Luis Obispo | 15,000 | Community | Surface water |
| Nipomo Comm Services Dist | San Luis Obispo | 13,771 | Community | Purchased 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, “City of Arroyo Grande Utilities Division, PWSID CA4010001, California”, https://aquacensus.com/water-systems/california/city-of-arroyo-grande-utilities-division-ca4010001 (data as of October 1, 2026).