Public water system · CA2210937
ActiveMariposa County Public Works Department
At a glance
Mariposa County Public Works Department (PWSID CA2210937) is an active non-transient non-community water system in Mariposa County, California. It reports serving 55 people through 6 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in January 2017.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
55
Service connections
6
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Mariposa County Public Works Department compare with other water systems in Mariposa County?
By EPA's size categories, Mariposa County Public Works Department is a very small system (500 people or fewer). Mariposa County has 67 active public water systems. Its population served is well below the county average of 381 people per system, and accounts for 0.2% of the 25,508 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Mariposa County Public Works Department is well below that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. California has 1,466 active non-transient non-community water systems, 20% 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 Mariposa County Public Works Department?
EPA lists Mariposa County Public Works Department 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. 21 of the 67 active systems in Mariposa County (31%) are also owned by a local government.
Does Mariposa County Public Works Department have drinking water violations?
Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in January 2017. The violations listed here began between April 2014 and January 2017. By type: 10 contaminant level above the legal limit and 2 monitoring and reporting. The contaminant or rule involved most often is Arsenic (10 of them). EPA lists 12 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 |
|---|---|---|---|---|
| 2017-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2016-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2016-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2016-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2015-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2015-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2015-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2015-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2015-01-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2014-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2014-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
| 2014-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | Resolved |
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.
Mariposa County Public Works Department: frequently asked questions
Who runs Mariposa County Public Works Department?
Mariposa County Public Works Department (PWSID CA2210937) is a non-transient non-community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Mariposa County Public Works Department serve?
Mariposa County Public Works Department reports serving 55 people through 6 service connections in Mariposa County, California.
Where does Mariposa County Public Works Department 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 Mariposa County Public Works Department have any drinking water violations?
Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in January 2017. 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 Mariposa County Public Works Department'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, 10 are health-based, and the most recent began in January 2017. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Mariposa County Public Works Department's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Mariposa County Public Works Department is a non-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.
Other water systems in Mariposa County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Yosemite Nps-Glacier Point | Mariposa | 4,000 | Transient non-community | Surface water |
| Blm-Briceburg Water System | Mariposa | 3,196 | Transient non-community | Groundwater |
| Mariposa Public Utility Dist | Mariposa | 2,000 | Community | Surface water |
| Yosemite Nps-Bridalveil Fall | Mariposa | 1,163 | Transient non-community | Groundwater |
| Mid - Mc Swain Rec Area | Mariposa | 1,119 | Transient non-community | Surface water |
| Yosemite Nps-Yosemite Valley | Mariposa | 1,000 | 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, “Mariposa County Public Works Department, PWSID CA2210937, California”, https://aquacensus.com/water-systems/california/mariposa-county-public-works-department-ca2210937 (data as of October 1, 2026).