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Mariposa County, California — public water systems

At a glance

67 active public water systems are filed under Mariposa County, California in EPA's SDWIS records, together reporting 25,508 people served. The largest is Yosemite Nps-Glacier Point, which reports serving 4,000 people. 11 are community water systems serving people where they live; the other 56 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.

Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.

Active systems

67

Population served

25.5K

Community systems

11

Groundwater share

86.6%

How does Mariposa County compare with other California counties?

Mariposa County has the 39th-most active public water systems among the 201 counties listed for active California systems in EPA records; among the 72 with 3 or more systems, the median has 73. Its systems report 25,508 people served in total, the 54th-largest county figure in the state and less than 0.1% of the statewide total. The average system here reports serving 381 people, well below the California average of 5,706. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.

Where does Mariposa County's drinking water come from?

By primary water source, Mariposa County's active systems draw on groundwater (58, 87%), surface water (8, 12%) and purchased surface water (1, 1.5%). Overall, 87% rely mainly on groundwater (including purchased groundwater) and 13% on surface water, compared with 85% and 15% across California. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Yosemite Nps-Glacier Point, draws primarily on surface water.

What kinds of water systems operate in Mariposa County?

Mariposa County's active systems break down as 11 community systems (16%), 9 non-transient non-community systems (13%) and 47 transient non-community systems (70%). 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. 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. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as private (49%), local government (31%) and federal government (19%).

The 50 largest water systems in Mariposa County

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Active public water systems in Mariposa County, California
#Water systemCountyPopulation servedTypeSource
1Yosemite Nps-Glacier PointMariposa4,000Transient non-communitySurface water
2Blm-Briceburg Water SystemMariposa3,196Transient non-communityGroundwater
3Mariposa Public Utility DistMariposa2,000CommunitySurface water
4Yosemite Nps-Bridalveil FallMariposa1,163Transient non-communityGroundwater
5Mid - Mc Swain Rec AreaMariposa1,119Transient non-communitySurface water
6Yosemite Nps-Badger PassMariposa1,000Transient non-communityGroundwater
7Yosemite Nps-Yosemite ValleyMariposa1,000CommunityGroundwater
8Delaware North Parks Services at TenayaMariposa800Non-transient non-communityGroundwater
9Ponderosa Basin Mutual Wtr CoMariposa798CommunityGroundwater
10Yosemite View LodgeMariposa750Non-transient non-communityGroundwater
11Cedar LodgeMariposa656CommunityGroundwater
12Yosemite Nps-El PortalMariposa635CommunityGroundwater
13Yosemite Nps-Crane FlatMariposa500Transient non-communityGroundwater
14Mid - Mc Clure Point Rec AreaMariposa470Transient non-communitySurface water
15Mcusd - Woodland Elementary SchoolMariposa466Non-transient non-communityGroundwater
16Yosemite Nps-Bridalveil Creek CgMariposa450Transient non-communityGroundwater
17Yosemite West Water SystemMariposa420CommunityGroundwater
18Mid - Barrett CoveMariposa407Transient non-communityGroundwater
19Yosemite Nps-May Lake CampMariposa300Transient non-communitySurface water
20Autocamp-YosemiteMariposa290Transient non-communityGroundwater
21Mcclure Boat Club, Inc..Mariposa286CommunitySurface water
22Mariposa Pines MutualMariposa284CommunityGroundwater
23The Cottages at Tenaya LodgeMariposa265Transient non-communityGroundwater
24Mcpr-Cathey S Valley ParkMariposa250Transient non-communityGroundwater
25Fishcamp Mutual Water CompanyMariposa239Transient non-communityGroundwater
26Camp WawonaMariposa222Transient non-communityGroundwater
27Yosemite Nps-Arch RockMariposa200Transient non-communityGroundwater
28Mariposa District FairgroundMariposa200Transient non-communityGroundwater
29New Life Calvary Chapel of MariposaMariposa200Transient non-communityGroundwater
30Mpwd-Coulterville Csa 1Mariposa193CommunityGroundwater
31Summerdale CampgroundMariposa175Transient non-communityGroundwater
32Mcusd - Sierra Foothill Charter SchoolMariposa157Non-transient non-communityPurchased surface water
33Yosemite Nps-Sunrise HiMariposa150Transient non-communitySurface water
34Yosemite Nps-WawonaMariposa150CommunitySurface water
35Mid -Horseshoe Bend Rec AreaMariposa142Transient non-communityGroundwater
36Mcusd - Mariposa Junior High SchoolMariposa134Non-transient non-communityGroundwater
37Yosemite Terrace EstatesMariposa130CommunityGroundwater
38Yosemite Bug HostelMariposa122Transient non-communityGroundwater
39Green Meadows Outdoor SchoolMariposa119Transient non-communityGroundwater
40Wildhaven Yosemite Water SystemMariposa100Transient non-communityGroundwater
41Redwoods Main Water SystemMariposa93Transient non-communityGroundwater
42Mid - Bagby Recreation AreaMariposa85Transient non-communityGroundwater
43North Wawona Estates (B System)Mariposa81Transient non-communityGroundwater
44White Chief Mountain LodgeMariposa73Transient non-communityGroundwater
45LDS Church MariposaMariposa65Transient non-communityGroundwater
46Yosemite'S Scenic WondersMariposa65Transient non-communityGroundwater
47Wampum Hill Trailer VillageMariposa62Transient non-communityGroundwater
48Shore Fun R.V. ParkMariposa60Transient non-communityGroundwater
49Mariposa Industrial Park Water CompanyMariposa60Transient non-communityGroundwater
50Yosemite Ridge ResortMariposa60Transient non-communityGroundwater

All other water systems in Mariposa County (17)

The remaining active systems filed under Mariposa County, largest first, with the population each reports serving.

Mariposa County water systems: frequently asked questions

How many public water systems are in Mariposa County, California?

EPA's SDWIS records file 67 active public water systems under Mariposa County, California: 11 community systems (16%), 9 non-transient non-community systems (13%) and 47 transient non-community systems (70%).

Who supplies drinking water in Mariposa County, CA?

The largest community water systems filed under Mariposa County are Mariposa Public Utility Dist (2,000 people served), Yosemite Nps-Yosemite Valley (1,000 people served) and Ponderosa Basin Mutual Wtr Co (798 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.

Does Mariposa County's drinking water come from groundwater or surface water?

Of the 67 active public water systems in Mariposa County, 87% draw mainly on groundwater and 13% on surface water, counting purchased supplies. The largest system, Yosemite Nps-Glacier Point, uses surface water.

Where can I find a water quality report for Mariposa County?

Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 11 community systems are filed under Mariposa County, so the report to look for is the one from the system that supplies your address.

How can I check violations for a water system in Mariposa County?

Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.

More California water systems

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, “Public water systems in Mariposa County, California”, https://aquacensus.com/water-systems/california/mariposa (data as of October 1, 2026).