Pima County, Arizona
USDA's soil survey flags shrink-swell clay on 9% of Pima County's mapped land and a shallow water table under basements on 0%, both below the national shares of 15% and 29%. The soil survey maps 87% of the county's land area; these shares describe the mapped part.
39.7% of the county is in drought on the November 3, 2026 Drought Monitor map, down from 41.5% a week earlier. FEMA's flood data list 107 flood losses here since 2016, 2% of them in buildings with basements. 40% of homes were built before 1980, against 50% nationally; the median home dates from 1986.
Data as of November 3, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, November 3, 2026
of homes built before 1980
Soil under Pima County
| Expansive clay (limits slab homes) | 8.7% |
| High water table (limits basements) | 0.0% |
| Septic fields very limited | 50.0% |
| Clay swell (LEP, by area) | 2.9% |
| High-swell land (LEP 6%+) | 6.6% |
| Urban land, not rated | 1.0% |
| Mapped soil | 5,136,797 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Hayhook | 3% | n/a |
| Bucklebar | 3% | n/a |
| Mohall | 3% | n/a |
| Gunsight | 2% | n/a |
| Stagecoach | 2% | n/a |
| Tubac | 2% | n/a |
How we count · survey areas AZ646 (2025-08-26), AZ653 (2025-08-27), AZ668 (2025-08-27), AZ669 (2025-08-27), AZ703 (2025-08-27)
What the numbers mean here
Rain over the 12 months to August 2026: 11.46 in, 0.10 in above the 1991-2020 average year of 11.36 in.
USDA rates 50% of the land very limited for septic absorption fields.
With shrink-swell clay on 9% and a shallow water table on 0% of the land, the soil survey points to neither problem across most of Pima County; conditions still vary lot by lot.
Drought
39.7% of the county is in drought (D1 or worse) on the November 3, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 8 weeks, most recently on the December 30, 2025 map.
| Category, November 3, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 47.4% |
| D1 moderate drought or worse | 39.7% |
| D2 severe or worse | 21.6% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
107 flood losses since 2016, $1.6 million paid. The worst year was 2016, with 27. Foundations of the buildings, where recorded: 2% basements, 83% slabs, 2% crawl spaces, 13% elevated. Median water depth outside the building: 7 in.
| Year | Flood losses |
|---|---|
| 2016 | 27 |
| 2017 | 6 |
| 2018 | 12 |
| 2019 | 8 |
| 2020 | 3 |
| 2021 | 24 |
| 2022 | 8 |
| 2023 | 12 |
| 2024 | 2 |
| 2025 | 3 |
| 2026 to date | 2 |
Rain
| Average year, 1991-2020 | 11.36 in |
| 12 months to August 2026 | 11.46 in (+0.10) |
| 2025 | 8.62 in (-2.74) |
| Wettest year since 1895 | 1983: 24.17 in |
| Driest year since 1895 | 2020: 5.60 in |
| Days with 1 inch or more, normal at KITT PEAK (16 mi away) | 4.8 |
Homes
| Housing units | 479,939 |
| Median year built | 1986 |
| Built before 1980 | 40% |
| Built 2000 or later | 28% |
| Owner-occupied | 65% |
| Median value, owner-occupied | $319,700 |
| Single-family detached | 60% |
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 |
|---|---|---|---|
| Pinal County, AZ | 60 mi | 15% | under 1% |
| Santa Cruz County, AZ | 69 mi | 16% | 0% |
| Maricopa County, AZ | 94 mi | 3% | 1% |
| Cochise County, AZ | 119 mi | 28% | under 1% |
| Graham County, AZ | 124 mi | 32% | under 1% |
| Gila County, AZ | 128 mi | 30% | under 1% |
| Yuma County, AZ | 132 mi | 1% | under 1% |
| Greenlee County, AZ | 167 mi | 35% | 1% |
Sources: USDA SSURGO (August 27, 2025) · US Drought Monitor (November 3, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status