11,006 people (2024 Census estimate, −0.1% since 2020)
563 square miles of land · 20 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 Lake County in the area they serve, reporting 15,667 people served in all (a system that crosses county lines counts its whole population).
| MADISON groundwater · local government · SD4600199 | 6,191 served |
| BIG SIOUX COMMUNITY WATER SYSTEM groundwater · private · SD4600429 | 5,800 served |
| KINGBROOK III RURAL WATER SYSTEM groundwater · private · SD4600874 | 2,973 served |
| CHESTER SANITARY DISTRICT buys groundwater · local government · SD4600088 | 363 served |
| WENTWORTH buys groundwater · local government · SD4600419 | 181 served |
| RAMONA buys groundwater · local government · SD4600252 | 159 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 11 people were held in Lake County's jail, in Vera's latest figure (2023), or 172 per 100,000 residents ages 15–64. In 2018 it was about 4.
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.
4 school districts have their office in Lake County. School taxes are usually the largest part of a property tax bill.
Spent $13.1 million — $12.7 million to run schools, about $11,106 per student, plus $229,000 on buildings and equipment. Money in: $9.8 million local (mostly property tax), $3.8 million state, $1.8 million federal. Long-term debt: $8.3 million.
Spent $6.6 million — $5.9 million to run schools, about $10,325 per student, plus $677,000 on buildings and equipment. Money in: $4 million local (mostly property tax), $2.2 million state, $542,000 federal. Long-term debt: $35,000.
Spent $2.7 million — $2.5 million to run schools, about $13,349 per student, plus $142,000 on buildings and equipment. Money in: $1.7 million local (mostly property tax), $1.2 million state, $208,000 federal. Long-term debt: $466,000.
Spent $3 million — $2.8 million to run schools, about $17,541 per student, plus $218,000 on buildings and equipment. Money in: $2 million local (mostly property tax), $712,000 state, $223,000 federal. Long-term debt: $2,000.
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 Lake County about $11.7 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.
79 bridges in Lake County: 35 in good condition, 40 fair, and 4 poor (5.1%). “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.
| 461 AVE over CK · built 1950 | 580 vehicles a day |
| 449 AVE over CK · built 1930 | 290 vehicles a day |
| 231 ST over EAST FORK VERMILLION RV · built 1930 | 55 vehicles a day |
| 464 AVE over BATTLE CK · built 1930 | 15 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $11.9 million of work in Lake County in fiscal 2025, about $1,076 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 South Dakota 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 Lake 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 Lake County built: brayden.ozark@gmail.com.
More of South Dakota: the state government and every county in South Dakota.
Nearby counties: Moody County (22 mi) · Miner County (24 mi) · McCook County (27 mi) · Brookings County (29 mi) · Kingsbury County (30 mi) · Minnehaha County (30 mi).