485,375 people (2024 Census estimate, −0.6% since 2020)
1,575 square miles of land · 308 people per square mile
“Highest” and “lowest” are just order, not grades: a high rank for poverty or hazard losses means more of it. Each figure's source is in its section below.
129 active community water systems list Sonoma County in the area they serve, reporting 430,937 people served in all (a system that crosses county lines counts its whole population).
| SANTA ROSA, CITY OF groundwater · local government · CA4910009 | 178,452 served |
| PETALUMA, CITY OF groundwater · local government · CA4910006 | 61,427 served |
| ROHNERT PARK, CITY OF groundwater · local government · CA4910014 | 43,821 served |
| WINDSOR, TOWN OF groundwater · local government · CA4910017 | 25,561 served |
| VALLEY OF THE MOON WATER DISTRICT groundwater · local government · CA4910013 | 23,140 served |
| HEALDSBURG, CITY OF groundwater (surface-influenced) · local government · CA4910005 | 10,972 served |
| SONOMA, CITY OF groundwater · local government · CA4910012 | 10,619 served |
| CLOVERDALE, CITY OF groundwater (surface-influenced) · private · CA4910002 | 8,710 served |
Source: U.S. EPA Safe Drinking Water Information System (SDWIS), active community systems, . Look up any system's violations and test results with EPA's search using its ID.
About 678 people were held in Sonoma County's jail, in Vera's latest figure (2025). In 2020 it was about 743.
Source: Vera Institute of Justice, Incarceration Trends (built from federal Bureau of Justice Statistics jail surveys). Counties without their own jail, or that share one, may show no figure.
39 school districts have their office in Sonoma County. School taxes are usually the largest part of a property tax bill.
Spent $289.5 million — $264.6 million to run schools, about $17,723 per student, plus $9.9 million on buildings and equipment. Money in: $160.8 million local (mostly property tax), $122.2 million state, $27.3 million federal. Long-term debt: $244.3 million.
Spent $133.9 million — $116.1 million to run schools, about $16,390 per student, plus $11.7 million on buildings and equipment. Money in: $71 million local (mostly property tax), $61.5 million state, $8.3 million federal. Long-term debt: $53.3 million.
Spent $103.5 million — $95.3 million to run schools, about $15,849 per student, plus $1.8 million on buildings and equipment. Money in: $59.6 million local (mostly property tax), $51.8 million state, $6.7 million federal. Long-term debt: $164 million.
Spent $96.8 million — $72.2 million to run schools, about $15,579 per student, plus $19 million on buildings and equipment. Money in: $44.2 million local (mostly property tax), $41.5 million state, $3.8 million federal. Long-term debt: $99 million.
Spent $112.2 million — $75.9 million to run schools, about $23,762 per student, plus $31 million on buildings and equipment. Money in: $68.8 million local (mostly property tax), $19.2 million state, $6.4 million federal. Long-term debt: $128.6 million.
Spent $62.9 million — $57.8 million to run schools, about $18,814 per student, plus $1.4 million on buildings and equipment. Money in: $38.9 million local (mostly property tax), $28.4 million state, $3.7 million federal. Long-term debt: $50.1 million.
Spent $39 million — $30.6 million to run schools, about $16,647 per student, plus $6.5 million on buildings and equipment. Money in: $19 million local (mostly property tax), $17.9 million state, $1.9 million federal. Long-term debt: $50 million.
Spent $37.9 million — $32.4 million to run schools, about $20,411 per student, plus $3.1 million on buildings and equipment. Money in: $27 million local (mostly property tax), $12.4 million state, $2.3 million federal. Long-term debt: $63.3 million.
And 31 more.
Source: U.S. Census Bureau, 2023 Annual Survey of School System Finances. Districts are listed by the county of their main office; some serve neighboring counties too.
Source: County Health Rankings & Roadmaps 2025 (University of Wisconsin Population Health Institute), which gathers federal data (CDC, Census, and others); measures cover different recent years. Blank lines aren't reported for small counties.
Overall risk: Relatively High compared with other U.S. counties. FEMA estimates natural hazards cost Sonoma County about $604.7 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
611 bridges in Sonoma County: 138 in good condition, 441 fair, and 32 poor (5.2%). “Poor” means a main part — the deck, the beams, or the supports — is rated 4 or lower on the federal 0–9 scale. It doesn't mean unsafe to drive; unsafe bridges are closed.
| US HIGHWAY 101 over DRY CREEK ROAD · built 1960 | 45,500 vehicles a day |
| U.S. HIGHWAY 101 over WESTSIDE RD · built 1960 | 45,500 vehicles a day |
| US HIGHWAY 101 SB over CHIQUITA ROAD · built 1960 | 22,500 vehicles a day |
| WASHINGTON ST over PETALUMA RIVER · built 1970 | 21,900 vehicles a day |
| OLD REDWOOD HWY over WILLOW BROOK CREEK · built 1999 | 19,980 vehicles a day |
| ARNOLD DRIVE over SONOMA CREEK · built 1930 | 13,900 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $177.8 million of work in Sonoma County in fiscal 2025, about $364 per resident — to the county, cities, schools, hospitals, nonprofits and others.
Source: USAspending.gov, grants by place of performance, fiscal 2025 (Oct. 2024 to Sept. 2025). Search it by county to see each award.
From Grants.gov: posted grants listing county governments as eligible, soonest deadline first; research-only and overseas programs left out; list updated 2026-10-13, refreshed weekly. 62 are open in all. Cities, towns, school districts and nonprofits have their own lists there.
General election: Tuesday, November 3, 2026. Ballots mailed; drop boxes open: 2026-10-05. Last day to register to vote: 2026-10-19. Early in-person voting: 2026-10-24 to 2026-11-03. Election Day: 2026-11-03. Last day for mailed ballots to arrive: 2026-11-10.
Source: California Secretary of State — Nov. 3, 2026 key dates · California Official Voter Information Guide — dates to remember · California Secretary of State — make a plan to vote
The budget, property tax rates, audits, local officials and offices for Sonoma County come from the county's own records, which we haven't gathered — not gathered, never hidden. See what a full county site looks like, or ask to have Sonoma County built: brayden.ozark@gmail.com.
More of California: the state government and every county in California.
Nearby counties: Napa County (32 mi) · Marin County (34 mi) · Lake County (41 mi) · San Francisco County (55 mi) · Solano County (56 mi) · Yolo County (56 mi).