Mariposa County | Public water system SAFER profile
Data date: July 31, 2026
Page 1 of 3

Mariposa County public water systems

Status classification

Share of listed systems, followed by the count, reported population, and funding in each status.

At-Risk19%
Potentially At-Risk12%
Not At-Risk56%
Failing
At-Risk
Potentially At-Risk
Not At-Risk
Not Assessed
Systems
1
3
2
9
1
Population
130
3,157
1,055
3,022
119
Funding since 2017
$0
$1M
$0
$0
$0

Key figures

16
public water systems
7,483
reported population
69%
serve 500 people or fewer
$1M
reported funding since 2017

System locations

Points show reported system locations. They do not represent service-area boundaries.

Each point represents one system record. Nearby or overlapping points can conceal multiple systems.

Summary

Mariposa County has 16 public water systems in the SAFER dataset. Of these, 4 (25%) are classified as Failing or At-Risk.

Those systems report serving 3,287 people. The county profile is also shaped by small systems: 11 systems serve 500 people or fewer.

1 system is listed as Not Assessed, serving 119 people, so Not Assessed should not be read as a low-risk classification.

Reported funding since 2017 totals $1M across 1 system. Technical assistance funding totals $343K.

System counts and reported population

At-Risk systems make up 19% of listed systems and 42% of reported population. A few large systems drive that population, so it reaches more people than its system count suggests.

Mariposa County | Public water system SAFER profile
Data date: July 31, 2026
Page 2 of 3

Risk profile

Risk in Mariposa County is distributed across four dimensions. Accessibility contributes the largest share of the combined weighted risk score at 42%. Across all individual indicators, No intertie appears most often, affecting 15 of 15 assessed systems.

Water Quality
13%
of combined weighted risk
State 32% · ▼ 18 pts
Most common flagWater quality trends toward MCL
Accessibility
42%
of combined weighted risk
State 36% · ▲ 6 pts
Most common flagNo intertie
Affordability
23%
of combined weighted risk
State 17% · ▲ 6 pts
Most common flagHousehold socioeconomic burden
TMF Capacity
21%
of combined weighted risk
State 15% · ▲ 6 pts
Most common flagTotal net annual income

Water Quality

Water Quality accounts for 13% of the county’s combined weighted risk score. Water quality trends toward MCL appears in 2 of 15 assessed systems. Emerging contaminants is next, appearing in 2 of 15 assessed systems.

Each indicator was assessed for 15 systems.

Accessibility

Accessibility accounts for 42% of the county’s combined weighted risk score. No intertie appears in 15 of 15 assessed systems. Limited water sources is next, appearing in 7 of 15 assessed systems.

Each indicator was assessed for 15 systems.

Affordability

Affordability accounts for 23% of the county’s combined weighted risk score. Household socioeconomic burden appears in 5 of 15 assessed systems. Share of household income is next, appearing in 3 of 12 assessed systems.

Indicator denominators range from 12 to 15 assessed systems.

TMF Capacity

TMF Capacity accounts for 21% of the county’s combined weighted risk score. Total net annual income appears in 8 of 15 assessed systems. Operating ratio is next, appearing in 7 of 15 assessed systems.

Indicator denominators range from 13 to 15 assessed systems.

Mariposa County | Public water system SAFER profile
Data date: July 31, 2026
Page 3 of 3

Patterns and context

The countywide totals hide important differences among systems. The panels below show how SAFER status varies by system size and service-area economic status, what conditions appear among Failing systems, and how reported funding is distributed across the 16 systems in Mariposa County.

Status by system size

SAFER status within each population group

Among systems serving 500 people or fewer, 2 of 11 are Failing or At-Risk. The highest concentration occurs among systems serving 501 to 3,300, at 40%.

Economic context

Orange shows Failing or At-Risk systems within each service-area group

DAC and SDAC service areas contain 16 of 16 listed systems. Within those two groups, 4 systems are Failing or At-Risk.

Conditions among Failing systems

A system can appear under more than one condition

No primary analytes were listed for Failing systems.

Among 1 Failing systems, 1 report secondary MCL violation. No primary analytes are listed for these systems.

Reported funding

Totals since 2017 and number of systems reporting funding

Funding since 2017 totals $1M across 1 system. At-Risk systems account for 100% of that total. Reported technical assistance funding adds $343K.

Key takeaways

25%

of systems are Failing or At-Risk

That represents 4 systems reporting service to 3,287 people. That is below the statewide average of 33%.

42%

of weighted risk comes from Accessibility

The most widespread individual flag is no intertie, found in 15 of 15 assessed systems. Statewide, Accessibility accounts for 36% of weighted risk.

69%

of systems serve 500 people or fewer

Small systems account for 11 of the county’s 16 listed systems. That is above the statewide average of 61%.