Boone County, Iowa
A shallow water table limits basements on 64% of Boone County's mapped land, a higher share than 77% of US counties. Shrink-swell clay limits houses without basements on 9%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 6 flood losses here since 2016. 69% of homes were built before 1980, against 50% nationally; the median home dates from 1960.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Boone County
| Expansive clay (limits slab homes) | 8.5% |
| High water table (limits basements) | 63.7% |
| Septic fields very limited | 75.9% |
| Clay swell (LEP, by area) | 3.5% |
| High-swell land (LEP 6%+) | 5.9% |
| Mapped soil | 367,200 acres |
How we count · survey areas IA015 (2025-09-08)
What the numbers mean here
On 64% of Boone County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 40.63 in, 4.66 in above the 1991-2020 average year of 35.97 in.
USDA rates 76% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. No part of the county was in drought in the last 52 weeks.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
6 flood losses since 2016, $56,255 paid. The worst year was 2018, with 3.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 3 |
| 2019 | 2 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 35.97 in |
| 12 months to August 2026 | 40.63 in (+4.66) |
| 2025 | 41.47 in (+5.50) |
| Wettest year since 1895 | 1993: 51.02 in |
| Driest year since 1895 | 1910: 19.06 in |
| Days with 1 inch or more, normal at BOONE (2 mi away) | 8.6 |
Homes
| Housing units | 12,041 |
| Median year built | 1960 |
| Built before 1980 | 69% |
| Built 2000 or later | 15% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $212,400 |
| Single-family detached | 80% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Greene County, IA | 23 mi | 11% | 71% |
| Story County, IA | 24 mi | 9% | 64% |
| Dallas County, IA | 25 mi | 17% | 60% |
| Hamilton County, IA | 27 mi | 32% | 91% |
| Webster County, IA | 30 mi | 27% | 88% |
| Polk County, IA | 31 mi | 13% | 52% |
| Guthrie County, IA | 38 mi | 62% | 66% |
| Hardin County, IA | 43 mi | 17% | 57% |
Sources: USDA SSURGO (September 8, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status