12,378 people (2024 Census estimate, +3.8% since 2020)
588 square miles of land · 21 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.
12 active community water systems list Lyon County in the area they serve, reporting 12,196 people served in all (a system that crosses county lines counts its whole population).
| ROCK RAPIDS MUNICIPAL WATER WORKS groundwater · local government · IA6065092 | 2,611 served |
| LYON-SIOUX RWS-DOON groundwater · private · IA6000733 | 1,765 served |
| LYON-SIOUX RWS-BIG SIOUX groundwater · private · IA6000755 | 1,530 served |
| LYON-SIOUX RWS-ROCK RAPIDS buys groundwater · private · IA6000800 | 1,187 served |
| GEORGE WATER SUPPLY groundwater · local government · IA6028081 | 1,082 served |
| INWOOD WATER SUPPLY buys groundwater · local government · IA6040076 | 928 served |
| LARCHWOOD WATER SUPPLY buys groundwater · local government · IA6050059 | 926 served |
| DOON WATER SUPPLY buys groundwater · local government · IA6015047 | 619 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 4 people were held in Lyon County's jail, in Vera's latest figure (2021), or 53 per 100,000 residents ages 15–64. In 2016 it was about 12.
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 Lyon County. School taxes are usually the largest part of a property tax bill.
Spent $13.7 million — $11.2 million to run schools, about $11,291 per student, plus $1.8 million on buildings and equipment. Money in: $6.7 million local (mostly property tax), $7.3 million state, $1 million federal. Long-term debt: $3.4 million.
Spent $11.8 million — $9.9 million to run schools, about $12,492 per student, plus $1.2 million on buildings and equipment. Money in: $5.5 million local (mostly property tax), $6.4 million state, $890,000 federal. Long-term debt: $1.8 million.
Spent $6.4 million — $5.2 million to run schools, about $12,192 per student, plus $605,000 on buildings and equipment. Money in: $4.2 million local (mostly property tax), $3.8 million state, $561,000 federal. Long-term debt: $845,000.
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 Lyon County about $10.9 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Very Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
273 bridges in Lyon County: 104 in good condition, 99 fair, and 70 poor (25.6%). “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.
| A26 (180TH ST) over BIG SIOUX RIVER · built 1977 | 1,017 vehicles a day |
| FM over KLONDIKE CREEK · built 1962 | 1,017 vehicles a day |
| FM over ROCK RIVER · built 1966 | 977 vehicles a day |
| FM over NELSON CREEK · built 1966 | 789 vehicles a day |
| FM over OVERFLOW · built 1969 | 718 vehicles a day |
| FM over LITTLE ROCK RIVER · built 1954 | 709 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $2.1 million of work in Lyon County in fiscal 2025, about $176 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 Lyon 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 Lyon County built: brayden.ozark@gmail.com.
More of Iowa: the state government and every county in Iowa.
Nearby counties: Rock County, MN (20 mi) · Sioux County (21 mi) · Lincoln County, SD (27 mi) · Osceola County (29 mi) · Nobles County, MN (30 mi) · Minnehaha County, SD (35 mi).