Costilla County, Colorado
USDA's soil survey flags shrink-swell clay on under 1% of Costilla County's mapped land and a shallow water table under basements on 4%, both below the national shares of 15% and 29%. 100% of the county is in drought on the October 13, 2026 Drought Monitor map.
FEMA's flood data list 1 flood losses here since 2016. 44% of homes were built before 1980, against 50% nationally; the median home dates from 1985.
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 Costilla County
| Expansive clay (limits slab homes) | 0.4% |
| High water table (limits basements) | 3.7% |
| Septic fields very limited | 56.2% |
| Clay swell (LEP, by area) | 2.1% |
| High-swell land (LEP 6%+) | 0.9% |
| Mapped soil | 790,000 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| McGinty | 10% | n/a |
| Cososa | 9% | n/a |
| Tolvar | 7% | n/a |
| Trinchera | 6% | n/a |
| Fallriver | 5% | n/a |
| Uracca | 5% | n/a |
How we count · survey areas CO023 (2025-08-29), CO636 (2025-08-29)
What the numbers mean here
Rain over the 12 months to August 2026: 10.69 in, 6.79 in below the 1991-2020 average year of 17.48 in.
USDA rates 56% of the land very limited for septic absorption fields.
With shrink-swell clay on under 1% and a shallow water table on 4% of the land, the soil survey points to neither problem across most of Costilla County; conditions still vary lot by lot.
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 30 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 | 1.7% |
| D4 exceptional | 0% |
Flood losses since 2016
1 flood losses since 2016, $0 paid. The worst year was 2021, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 17.48 in |
| 12 months to August 2026 | 10.69 in (-6.79) |
| 2025 | 15.79 in (-1.69) |
| Wettest year since 1895 | 1941: 25.44 in |
| Driest year since 1895 | 1950: 8.22 in |
| Days with 1 inch or more, normal at ALAMOSA SAN LUIS AP (26 mi away) | 0.3 |
Homes
| Housing units | 2,433 |
| Median year built | 1985 |
| Built before 1980 | 44% |
| Built 2000 or later | 31% |
| Owner-occupied | 79% |
| Median value, owner-occupied | $184,700 |
| Single-family detached | 81% |
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 |
|---|---|---|---|
| Alamosa County, CO | 28 mi | 2% | 36% |
| Huerfano County, CO | 38 mi | 13% | 2% |
| Conejos County, CO | 41 mi | under 1% | 28% |
| Taos County, NM | 50 mi | 12% | 2% |
| Custer County, CO | 57 mi | 2% | 7% |
| Rio Grande County, CO | 58 mi | under 1% | 42% |
| Colfax County, NM | 63 mi | 52% | 2% |
| Saguache County, CO | 68 mi | 4% | 15% |
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