Delaware County, Iowa
A shallow water table limits basements on 53% of Delaware County's mapped land, a higher share than 69% of US counties. Shrink-swell clay limits houses without basements on 4%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 19 flood losses here since 2016. 66% of homes were built before 1980, against 50% nationally; the median home dates from 1967.
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 Delaware County
| Expansive clay (limits slab homes) | 4.4% |
| High water table (limits basements) | 53.4% |
| Septic fields very limited | 95.5% |
| Clay swell (LEP, by area) | 3.6% |
| High-swell land (LEP 6%+) | 6.8% |
| Mapped soil | 370,800 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Kenyon | 13% | n/a |
| Clyde | 10% | n/a |
| Fayette | 10% | 0% |
| Floyd | 9% | n/a |
| Downs | 4% | n/a |
| Nordness | 3% | n/a |
How we count · survey areas IA055 (2025-09-08)
What the numbers mean here
On 53% of Delaware 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: 40.02 in, 1.46 in above the 1991-2020 average year of 38.56 in.
USDA rates 96% 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. Part of the county was in drought in 13 of the last 52 weeks; the most was 97.2% of its area, in 7 weeks, most recently on the December 30, 2025 map.
| 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
19 flood losses since 2016, $442,327 paid. The worst year was 2018, with 14.
| Year | Flood losses |
|---|---|
| 2016 | 4 |
| 2017 | 0 |
| 2018 | 14 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 1 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 38.56 in |
| 12 months to August 2026 | 40.02 in (+1.46) |
| 2025 | 36.94 in (-1.62) |
| Wettest year since 1895 | 2018: 52.20 in |
| Driest year since 1895 | 1910: 20.05 in |
| Days with 1 inch or more, normal at MANCHESTER #2 (4 mi away) | 9.2 |
Homes
| Housing units | 8,169 |
| Median year built | 1967 |
| Built before 1980 | 66% |
| Built 2000 or later | 17% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $177,900 |
| Single-family detached | 86% |
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 |
|---|---|---|---|
| Buchanan County, IA | 24 mi | 2% | 78% |
| Dubuque County, IA | 25 mi | 9% | 25% |
| Clayton County, IA | 26 mi | 1% | 14% |
| Jones County, IA | 27 mi | 12% | 38% |
| Linn County, IA | 30 mi | 9% | 57% |
| Fayette County, IA | 36 mi | 1% | 59% |
| Grant County, WI | 44 mi | 23% | 11% |
| Benton County, IA | 44 mi | 33% | 73% |
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