Story County, Iowa
A shallow water table limits basements on 64% of Story 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 12 flood losses here since 2016. 47% of homes were built before 1980, against 50% nationally; the median home dates from 1984.
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 Story County
| Expansive clay (limits slab homes) | 9.2% |
| High water table (limits basements) | 63.6% |
| Septic fields very limited | 69.5% |
| Clay swell (LEP, by area) | 3.6% |
| High-swell land (LEP 6%+) | 6.0% |
| Mapped soil | 367,200 acres |
How we count · survey areas IA169 (2025-09-09)
What the numbers mean here
On 64% of Story 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: 40.11 in, 3.81 in above the 1991-2020 average year of 36.30 in.
USDA rates 69% 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
12 flood losses since 2016, $137,536 paid. The worst year was 2016, with 4.
| Year | Flood losses |
|---|---|
| 2016 | 4 |
| 2017 | 1 |
| 2018 | 3 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 1 |
| 2026 to date | 3 |
Rain
| Average year, 1991-2020 | 36.30 in |
| 12 months to August 2026 | 40.11 in (+3.81) |
| 2025 | 41.65 in (+5.35) |
| Wettest year since 1895 | 1993: 55.47 in |
| Driest year since 1895 | 1988: 18.58 in |
| Days with 1 inch or more, normal at AMES 5 SE (8 mi away) | 9.3 |
Homes
| Housing units | 41,887 |
| Median year built | 1984 |
| Built before 1980 | 47% |
| Built 2000 or later | 32% |
| Owner-occupied | 56% |
| Median value, owner-occupied | $258,700 |
| Single-family detached | 52% |
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 |
|---|---|---|---|
| Boone County, IA | 24 mi | 9% | 64% |
| Marshall County, IA | 25 mi | 42% | 47% |
| Polk County, IA | 25 mi | 13% | 52% |
| Hardin County, IA | 27 mi | 17% | 57% |
| Hamilton County, IA | 27 mi | 32% | 91% |
| Jasper County, IA | 32 mi | 40% | 55% |
| Dallas County, IA | 38 mi | 17% | 60% |
| Grundy County, IA | 43 mi | 59% | 67% |
Sources: USDA SSURGO (September 9, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status