Oklahoma County, Oklahoma
Shrink-swell clay limits houses without basements on 21% of Oklahoma County's mapped land, a higher share than 71% of US counties. A shallow water table limits basements on 3%.
100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 97 flood losses here since 2016, 6% of them in buildings with basements. 54% of homes were built before 1980, against 50% nationally; the median home dates from 1978.
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 Oklahoma County
| Expansive clay (limits slab homes) | 20.8% |
| High water table (limits basements) | 2.9% |
| Septic fields very limited | 70.7% |
| Clay swell (LEP, by area) | 4.0% |
| High-swell land (LEP 6%+) | 19.8% |
| Urban land, not rated | 14.6% |
| Mapped soil | 459,802 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Stephenville | 14% | 0% |
| Harrah | 11% | n/a |
| Darnell | 7% | n/a |
| Renthin | 7% | n/a |
| Newalla | 4% | n/a |
| Grainola | 3% | n/a |
How we count · survey areas OK109 (2025-08-29)
What the numbers mean here
Clay swell averages a linear extensibility of 4.0% by land area here, and 20% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 21% of the mapped land.
Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 21% of Oklahoma County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 22.02 in, 14.48 in below the 1991-2020 average year of 36.50 in.
USDA rates 71% of the land very limited for septic absorption fields.
Drought
100% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 37 weeks, most recently on the October 13, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 100% |
| D2 severe or worse | 100% |
| D3 extreme or worse | 100% |
| D4 exceptional | 2.4% |
Flood losses since 2016
97 flood losses since 2016, $2.5 million paid. The worst year was 2018, with 23. Foundations of the buildings, where recorded: 6% basements, 89% slabs, 6% crawl spaces. Median water depth outside the building: 6 in.
| Year | Flood losses |
|---|---|
| 2016 | 2 |
| 2017 | 8 |
| 2018 | 23 |
| 2019 | 20 |
| 2020 | 14 |
| 2021 | 14 |
| 2022 | 3 |
| 2023 | 5 |
| 2024 | 1 |
| 2025 | 6 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 36.50 in |
| 12 months to August 2026 | 22.02 in (-14.48) |
| 2025 | 42.76 in (+6.26) |
| Wettest year since 1895 | 1908: 55.51 in |
| Driest year since 1895 | 1954: 18.02 in |
| Days with 1 inch or more, normal at OKLAHOMA CITY WILL ROGERS AP (16 mi away) | 11 |
Homes
| Housing units | 360,591 |
| Median year built | 1978 |
| Built before 1980 | 54% |
| Built 2000 or later | 25% |
| Owner-occupied | 58% |
| Median value, owner-occupied | $222,900 |
| Single-family detached | 69% |
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 |
|---|---|---|---|
| Cleveland County, OK | 25 mi | 21% | 5% |
| Logan County, OK | 25 mi | 21% | 2% |
| Lincoln County, OK | 32 mi | 27% | 10% |
| Canadian County, OK | 32 mi | 20% | 4% |
| Pottawatomie County, OK | 35 mi | 23% | 6% |
| McClain County, OK | 37 mi | 12% | 5% |
| Kingfisher County, OK | 40 mi | 25% | 4% |
| Payne County, OK | 44 mi | 25% | 7% |
Sources: USDA SSURGO (August 29, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status