Sonoma County public water systems

Status classification

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

Failing16%

At-Risk12%

Potentially At-Risk11%

Not At-Risk58%

Failing

At-Risk

Potentially At-Risk

Not At-Risk

Not Assessed

Systems

25

19

17

90

4

Population

4,697

18,355

4,013

244,682

175,488

Funding since 2017

$2M

$260K

$0

$275K

Key figures

155

public water systems

447,235

reported population

81%

serve 500 people or fewer

$3M

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

Sonoma County has 155 public water systems in the SAFER dataset. Of these, 44 (28%) are classified as Failing or At-Risk.

Those systems report serving 23,052 people. The county profile is also shaped by small systems: 126 systems serve 500 people or fewer.

4 systems are listed as Not Assessed, serving 175,488 people, so Not Assessed should not be read as a low-risk classification.

Reported funding since 2017 totals $3M across 5 systems. Technical assistance funding totals $6M.

System counts and reported population

Not Assessed systems make up 3% of listed systems and 39% of reported population. That population sits in a few large systems outside the SAFER assessment’s scope, which generally have more capacity, so this reflects scope rather than hidden risk.

Risk profile

Risk in Sonoma County is distributed across four dimensions. Accessibility contributes the largest share of the combined weighted risk score at 39%. Across all individual indicators, No intertie appears most often, affecting 123 of 151 assessed systems.

Water Quality

of combined weighted risk

State 32% · ▼ 4 pts

Most common flagWater quality trends toward MCL

Accessibility

of combined weighted risk

State 36% · ▲ 3 pts

Most common flagNo intertie

Affordability

of combined weighted risk

State 17% · ▲ 1 pts

Most common flagHousehold socioeconomic burden

TMF Capacity

of combined weighted risk

State 15% · – 0 pts

Most common flagTotal net annual income

Water Quality

Water Quality accounts for 28% of the county’s combined weighted risk score. Water quality trends toward MCL appears in 58 of 151 assessed systems. Past presence on Failing list is next, appearing in 31 of 151 assessed systems.

Each indicator was assessed for 151 systems.

Accessibility

Accessibility accounts for 39% of the county’s combined weighted risk score. No intertie appears in 123 of 151 assessed systems. Limited water sources is next, appearing in 64 of 151 assessed systems.

Indicator denominators range from 138 to 151 assessed systems.

Affordability

Affordability accounts for 19% of the county’s combined weighted risk score. Household socioeconomic burden appears in 58 of 151 assessed systems. Share of household income is next, appearing in 23 of 131 assessed systems.

Indicator denominators range from 131 to 151 assessed systems.

TMF Capacity

TMF Capacity accounts for 14% of the county’s combined weighted risk score. Total net annual income appears in 62 of 148 assessed systems. Days cash on hand is next, appearing in 39 of 142 assessed systems.

Indicator denominators range from 142 to 151 assessed systems.

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 155 systems in Sonoma County.

Status by system size

SAFER status within each population group

Among systems serving 500 people or fewer, 37 of 126 are Failing or At-Risk. The highest concentration occurs among systems serving 501 to 3,300, at 36%.

Economic context

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

DAC and SDAC service areas contain 60 of 155 listed systems. Within those two groups, 24 systems are Failing or At-Risk.

Conditions among Failing systems

A system can appear under more than one condition

Frequently listed primary analytes

Nitrate2
Total Haloacetic Acids (Haa5)2
Tthm2
Arsenic1

Among 25 Failing systems, 13 report secondary MCL violation. The most frequently listed primary analytes are Nitrate, Total Haloacetic Acids (Haa5), and Tthm.

Reported funding

Totals since 2017 and number of systems reporting funding

Funding since 2017 totals $3M across 5 systems. Failing systems account for 80% of that total. Reported technical assistance funding adds $6M.

Key takeaways

28%

of systems are Failing or At-Risk

That represents 44 systems reporting service to 23,052 people. That is below the statewide average of 33%.

39%

of weighted risk comes from Accessibility

The most widespread individual flag is no intertie, found in 123 of 151 assessed systems. Statewide, Accessibility accounts for 36% of weighted risk.

81%

of systems serve 500 people or fewer

Small systems account for 126 of the county’s 155 listed systems. That is above the statewide average of 61%.