7,656 people (2024 Census estimate, −1.0% since 2020)
532 square miles of land · 14 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.
6 active community water systems list Decatur County in the area they serve, reporting 59,209 people served in all (a system that crosses county lines counts its whole population).
| RATHBUN REGIONAL WATER ASSN (RATHBUN) surface water · private · IA0400900 | 33,000 served |
| SIRWA #2 (CRESTON) surface water · private · IA8080701 | 20,793 served |
| LAMONI MUNICIPAL UTILITIES surface water · local government · IA2740050 | 2,029 served |
| LEON WATER SUPPLY surface water · local government · IA2742076 | 1,830 served |
| SIRWA #3 (LEON) buys surface water · private · IA2718755 | 1,373 served |
| GARDEN GROVE WATER SUPPLY buys surface water · local government · IA2725073 | 184 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 8 people were held in Decatur County's jail, in Vera's latest figure (2019), or 173 per 100,000 residents ages 15–64. In 2014 it was about 5.
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.
2 school districts have their office in Decatur County. School taxes are usually the largest part of a property tax bill.
Spent $11 million — $9.5 million to run schools, about $13,664 per student, plus $956,000 on buildings and equipment. Money in: $3.3 million local (mostly property tax), $6.8 million state, $1.8 million federal. Long-term debt: $2.4 million.
Spent $5.5 million — $4.3 million to run schools, about $11,442 per student, plus $835,000 on buildings and equipment. Money in: $2.3 million local (mostly property tax), $3.3 million state, $999,000 federal. Long-term debt: $765,000.
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: Very Low compared with other U.S. counties. FEMA estimates natural hazards cost Decatur County about $7.8 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively Moderate; social vulnerability: Relatively Moderate.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
199 bridges in Decatur County: 37 in good condition, 84 fair, and 78 poor (39.2%). “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 69 over ZADIE CREEK · built 1925 | 610 vehicles a day |
| FM over WELDON RIVER · built 1957 | 421 vehicles a day |
| FM over WELDON RIVER · built 1958 | 379 vehicles a day |
| FM over GRAND RIVER · built 1959 | 329 vehicles a day |
| FM over NORTH ELK CREEK · built 1939 | 278 vehicles a day |
| FM over SMALL NATURAL STREAM · built 1939 | 278 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $5.5 million of work in Decatur County in fiscal 2025, about $725 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 Iowa 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 Decatur 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 Decatur County built: brayden.ozark@gmail.com.
More of Iowa: the state government and every county in Iowa.
Nearby counties: Clarke County (20 mi) · Wayne County (24 mi) · Ringgold County (24 mi) · Mercer County, MO (25 mi) · Harrison County, MO (29 mi) · Lucas County (31 mi).