Adams County, Colorado
USDA's soil survey flags shrink-swell clay on 11% of Adams County's mapped land and a shallow water table under basements on 2%, both below the national shares of 15% and 29%. 62.2% of the county is in drought on the October 13, 2026 Drought Monitor map.
FEMA's flood data list 20 flood losses here since 2016. 37% of homes were built before 1980, against 50% nationally; the median home dates from 1991.
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 Adams County
| Expansive clay (limits slab homes) | 11.5% |
| High water table (limits basements) | 1.6% |
| Septic fields very limited | 34.5% |
| Clay swell (LEP, by area) | 3.8% |
| High-swell land (LEP 6%+) | 30.9% |
| Mapped soil | 764,964 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Weld | 13% | n/a |
| Ascalon | 11% | n/a |
| Adena | 10% | n/a |
| Colby | 7% | n/a |
| Vona | 6% | n/a |
| Platner | 6% | n/a |
How we count · survey areas CO001 (2025-08-29), CO031 (2025-08-29)
What the numbers mean here
Rain over the 12 months to August 2026: 11.67 in, 3.89 in below the 1991-2020 average year of 15.56 in.
With shrink-swell clay on 11% and a shallow water table on 2% of the land, the soil survey points to neither problem across most of Adams County; conditions still vary lot by lot.
Drought
62.2% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 46 of the last 52 weeks; the most was 100% of its area, in 13 weeks, most recently on the June 23, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 86.3% |
| D1 moderate drought or worse | 62.2% |
| D2 severe or worse | 37.1% |
| D3 extreme or worse | 15.8% |
| D4 exceptional | 2.1% |
Flood losses since 2016
20 flood losses since 2016, $109,028 paid. The worst year was 2022, with 7.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 1 |
| 2018 | 2 |
| 2019 | 0 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 7 |
| 2023 | 6 |
| 2024 | 3 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 15.56 in |
| 12 months to August 2026 | 11.67 in (-3.89) |
| 2025 | 14.64 in (-0.92) |
| Wettest year since 1895 | 2023: 23.10 in |
| Driest year since 1895 | 1939: 7.34 in |
| Days with 1 inch or more, normal at BYERS 5 ENE (14 mi away) | 2.5 |
Homes
| Housing units | 195,793 |
| Median year built | 1991 |
| Built before 1980 | 37% |
| Built 2000 or later | 37% |
| Owner-occupied | 69% |
| Median value, owner-occupied | $484,200 |
| Single-family detached | 62% |
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 |
|---|---|---|---|
| Arapahoe County, CO | 16 mi | 22% | 1% |
| Denver County, CO | 30 mi | 15% | 3% |
| Broomfield County, CO | 39 mi | 46% | 1% |
| Morgan County, CO | 39 mi | 10% | 3% |
| Elbert County, CO | 40 mi | 11% | 2% |
| Weld County, CO | 47 mi | 7% | 2% |
| Douglas County, CO | 49 mi | 3% | 2% |
| Jefferson County, CO | 53 mi | 17% | 2% |
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