Public water system · CA5510012
ActiveTud - Upper Basin Water System
At a glance
Tud - Upper Basin Water System (PWSID CA5510012) is an active community water system in Tuolumne County, California. It reports serving 13,280 people through 4,991 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 2 violations for this system; 1 is health-based, and the most recent began in April 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
13,280
Service connections
4,991
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Tud - Upper Basin Water System compare with other water systems in Tuolumne County?
By EPA's size categories, Tud - Upper Basin Water System is a large system (10,001 to 100,000 people). Tuolumne County has 117 active public water systems, and Tud - Upper Basin Water System is the largest of them by population served. Its population served is about 19 times the county average of 706 people per system, and accounts for 16% of the 82,611 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 Tud - Upper Basin Water System is about twice 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. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 609 California systems (8.1%) list surface water as their primary source.
Who owns and regulates Tud - Upper Basin Water System?
EPA lists Tud - Upper Basin Water System 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. 17 of the 117 active systems in Tuolumne County (15%) are also owned by a local government.
Does Tud - Upper Basin Water System have drinking water violations?
EPA's records list 2 violations for this system; 1 is health-based, and the most recent began in April 2025. The violations listed here began between December 1996 and April 2025. By type: 1 monitoring and 1 required treatment not met. The contaminants or rules involved are Revised Total Coliform Rule and Surface Water Treatment Rule. EPA lists 2 as resolved. 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 |
|---|---|---|---|---|
| 2025-04-01 | MonitoringMonitoring, Lab Certification/Method Error (RTCR) · code 3D | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 1996-12-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
All 2 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.
Tud - Upper Basin Water System: frequently asked questions
Who runs Tud - Upper Basin Water System?
Tud - Upper Basin Water System (PWSID CA5510012) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Tud - Upper Basin Water System serve?
Tud - Upper Basin Water System reports serving 13,280 people through 4,991 service connections in Tuolumne County, California.
Where does Tud - Upper Basin Water System get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does Tud - Upper Basin Water System have any drinking water violations?
EPA's records list 2 violations for this system; 1 is health-based, and the most recent began in April 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 Tud - Upper Basin Water System'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 2 violations for this system; 1 is health-based, and the most recent began in April 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 Tud - Upper Basin Water System's water quality report?
As a community water system, Tud - Upper Basin Water System 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 Tuolumne County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Tud - Sonora/Jamestown Water System | Tuolumne | 11,054 | Community | Surface water |
| Tud - Columbia Water System | Tuolumne | 5,463 | Community | Surface water |
| Peppery Bar and Grill, the | Tuolumne | 4,500 | Transient non-community | Groundwater |
| Cdcr - Sierra Conservation Center | Tuolumne | 3,571 | Community | Surface water |
| Groveland Community Serv Dist | Tuolumne | 3,400 | Community | Surface water |
| Lake Don Pedro Csd | Tuolumne | 3,240 | 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, “Tud - Upper Basin Water System, PWSID CA5510012, California”, https://aquacensus.com/water-systems/california/tud-upper-basin-water-system-ca5510012 (data as of October 1, 2026).