8,581 people (2024 Census estimate, +12.0% since 2020)
1,899 square miles of land · 5 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.
20 active community water systems list Boise County in the area they serve, reporting 4,107 people served in all (a system that crosses county lines counts its whole population).
| HORSESHOE BEND WATER SUPPLY surface water · private · ID4080024 | 750 served |
| IDAHO CITY WATER DEPT surface water · private · ID4080025 | 531 served |
| WILDERNESS RANCH OWNERS ASSOCIATION INC surface water · private · ID4080055 | 525 served |
| TERRACE LAKES WATER COMPANY groundwater · private · ID4080047 | 475 served |
| MOUNTAIN VIEW WATER AND ROAD ASSN groundwater · private · ID4080031 | 305 served |
| CASTLE MOUNTAIN CREEKS OWNERS ASSN surface water · private · ID4080007 | 250 served |
| DUQUETTE PINES HOMEOWNERS ASSOCIATION groundwater · private · ID4080016 | 163 served |
| SCRIVER WOODS HOMEOWNERS ASSN groundwater · private · ID4080034 | 160 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 14 people were held in Boise County's jail, in Vera's latest figure (2024), or 274 per 100,000 residents ages 15–64. In 2019 it was about 14.
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.
3 school districts have their office in Boise County. School taxes are usually the largest part of a property tax bill.
Spent $4.7 million — $4.4 million to run schools, about $13,080 per student, plus $164,000 on buildings and equipment. Money in: $847,000 local (mostly property tax), $3.2 million state, $762,000 federal.
Spent $4.5 million — $4.3 million to run schools, about $15,638 per student, plus $10,000 on buildings and equipment. Money in: $2.1 million local (mostly property tax), $2.9 million state, $961,000 federal. Long-term debt: $5.5 million.
Spent $4 million — $3.7 million to run schools, about $16,356 per student, plus $291,000 on buildings and equipment. Money in: $565,000 local (mostly property tax), $2.5 million state, $948,000 federal. Long-term debt: $530,000.
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 Low compared with other U.S. counties. FEMA estimates natural hazards cost Boise County about $16 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very Low; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
89 bridges in Boise County: 45 in good condition, 39 fair, and 5 poor (5.6%). “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.
| ANDERSON CREEK RD over ANDERSON CREEK · built 1983 | 100 vehicles a day |
| BOULDER CREEK ROAD over MORES CREEK · built 1982 | 50 vehicles a day |
| COTTONWD-BANNOCK over MORES CREEK · built 1962 | 30 vehicles a day |
| SHAFER CREEK ROAD over SHAFER CREEK · built 1914 | 20 vehicles a day |
| AVELENE CK. ROAD over GRIMES CREEK · built 1954 | 20 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $19.4 million of work in Boise County in fiscal 2025, about $2,554 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.
Registration deadlines, early voting and polling places for Idaho are on the federal site vote.gov, which links to the state's official election office.
The budget, property tax rates, audits, local officials and offices for Boise 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 Boise County built: brayden.ozark@gmail.com.
More of Idaho: the state government and every county in Idaho.
Nearby counties: Gem County (34 mi) · Elmore County (43 mi) · Ada County (45 mi) · Payette County (51 mi) · Canyon County (55 mi) · Camas County (58 mi).