1,172,607 people (2024 Census estimate, +0.6% since 2020)
717 square miles of land · 1,636 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.
39 active community water systems list Contra Costa County in the area they serve, reporting 578,266 people served in all (a system that crosses county lines counts its whole population).
| CONTRA COSTA WATER DISTRICT surface water · local government · CA0710003 | 210,500 served |
| CITY OF ANTIOCH surface water · local government · CA0710001 | 116,781 served |
| BRENTWOOD buys surface water · local government · CA0710004 | 64,513 served |
| CITY OF PITTSBURG buys surface water · local government · CA0710008 | 62,500 served |
| DIABLO WATER DISTRICT buys surface water · local government · CA0710007 | 47,158 served |
| CITY OF MARTINEZ buys surface water · local government · CA0710006 | 31,015 served |
| GOLDEN STATE WATER COMPANY - BAY POINT buys surface water · private · CA0710002 | 23,765 served |
| TOWN OF DISCOVERY BAY groundwater · local government · CA0710009 | 16,790 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 944 people were held in Contra Costa County's jail, in Vera's latest figure (2025). In 2020 it was about 858.
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.
19 school districts have their office in Contra Costa County. School taxes are usually the largest part of a property tax bill.
Spent $477.4 million — $455.6 million to run schools, about $15,351 per student, plus $12.1 million on buildings and equipment. Money in: $315.9 million local (mostly property tax), $220 million state, $16 million federal. Long-term debt: $424.9 million.
Spent $520.7 million — $446 million to run schools, about $15,273 per student, plus $47.4 million on buildings and equipment. Money in: $263.4 million local (mostly property tax), $285.6 million state, $45.7 million federal. Long-term debt: $413.7 million.
Spent $588.4 million — $492.1 million to run schools, about $19,122 per student, plus $38.2 million on buildings and equipment. Money in: $293.2 million local (mostly property tax), $393.7 million state, $51.1 million federal. Long-term debt: $1.3 billion.
Spent $285.4 million — $269.7 million to run schools, about $17,751 per student, plus $9.8 million on buildings and equipment. Money in: $85.7 million local (mostly property tax), $198.1 million state, $37.6 million federal. Long-term debt: $113.2 million.
Spent $222.1 million — $192.1 million to run schools, about $18,011 per student, plus $12.1 million on buildings and equipment. Money in: $64.3 million local (mostly property tax), $186.8 million state, $21.5 million federal. Long-term debt: $330.8 million.
Spent $168.7 million — $138.8 million to run schools, about $14,714 per student, plus $25.1 million on buildings and equipment. Money in: $52.5 million local (mostly property tax), $93 million state, $10.4 million federal. Long-term debt: $58.8 million.
Spent $165.6 million — $132.8 million to run schools, about $16,126 per student, plus $24.8 million on buildings and equipment. Money in: $82.3 million local (mostly property tax), $73.7 million state, $7.2 million federal. Long-term debt: $141.8 million.
Spent $116.4 million — $103.1 million to run schools, about $19,018 per student, plus $3.1 million on buildings and equipment. Money in: $102.9 million local (mostly property tax), $20 million state, $3.2 million federal. Long-term debt: $218.2 million.
And 11 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: Very High compared with other U.S. counties. FEMA estimates natural hazards cost Contra Costa County about $970.5 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.
622 bridges in Contra Costa County: 260 in good condition, 306 fair, and 56 poor (9.0%). “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.
| INTERSTATE 680 over MONUMENT BOULEVARD · built 1998 | 235,000 vehicles a day |
| INTERSTATE 680 over LAUREL DRIVE · built 1964 | 192,200 vehicles a day |
| INTERSTATE 80 over EL PORTAL DRIVE · built 1956 | 179,000 vehicles a day |
| INTERSTATE 80 over STATE ROUTE 4 & RAMPS · built 1958 | 179,000 vehicles a day |
| INTERSTATE 680 over GRAYSON CREEK · built 1962 | 169,000 vehicles a day |
| INTERSTATE 680 over WILLOW PASS ROAD · built 1962 | 130,000 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $348.5 million of work in Contra Costa County in fiscal 2025, about $299 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 Contra Costa 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 Contra Costa County built: brayden.ozark@gmail.com.
More of California: the state government and every county in California.
Nearby counties: Alameda County (19 mi) · Solano County (24 mi) · San Joaquin County (37 mi) · San Mateo County (42 mi) · Marin County (44 mi) · Napa County (45 mi).