Expansive Soil in Colorado: County Ratings
5 of the 63 rated counties in Colorado have a dominant shrink-swell rating of High or Very High. Each rating below is the NRCS shrink-swell class covering the largest share of the county's mapped soil acres, computed from USDA SSURGO data. Open a county for the full class breakdown and what it means for a slab foundation.
| County | Dominant class | High + Very High share | Survey coverage |
|---|---|---|---|
| Adams County | Low | 35% | 98% |
| Alamosa County | Low | 14% | 98% |
| Arapahoe County | High | 51% | 98% |
| Archuleta County | High | 43% | 98% |
| Baca County | Low | 32% | 100% |
| Bent County | Low | 17% | 99% |
| Boulder County | Low | 14% | 93% |
| Broomfield County | High | 86% | 99% |
| Chaffee County | Low | 1% | 74% * |
| Cheyenne County | Moderate | 9% | 100% |
| Clear Creek County | Low | 0% | 96% |
| Conejos County | Low | 2% | 99% |
| Costilla County | Low | 1% | 99% |
| Crowley County | High | 48% | 98% |
| Custer County | Low | 2% | 97% |
| Delta County | Moderate | 15% | 88% |
| Denver County | Moderate | 19% | 98% |
| Dolores County | Low | 14% | 99% |
| Douglas County | Low | 7% | 100% |
| Eagle County | Low | 6% | 99% |
| El Paso County | Low | 1% | 100% |
| Elbert County | Low | 29% | 98% |
| Fremont County | Low | 5% | 99% |
| Garfield County | Low | 3% | 98% |
| Gilpin County | Low | 0% | 98% |
| Grand County | Low | 7% | 96% |
| Gunnison County | Low | 8% | 91% |
| Hinsdale County | Low | 0% | 92% |
| Huerfano County | Low | 17% | 99% |
| Jackson County | Low | 20% | 97% |
| Jefferson County | Low | 23% | 97% |
| Kiowa County | Moderate | 16% | 99% |
| Kit Carson County | Moderate | 13% | 100% |
| La Plata County | Low | 13% | 95% |
| Lake County | Low | 0% | 87% |
| Larimer County | Low | 8% | 95% |
| Las Animas County | Low | 25% | 100% |
| Lincoln County | Low | 26% | 98% |
| Logan County | Low | 24% | 99% |
| Mesa County | Low | 16% | 96% |
| Moffat County | Low | 13% | 99% |
| Montezuma County | Low | 16% | 99% |
| Montrose County | Moderate | 27% | 95% |
| Morgan County | Low | 17% | 99% |
| Otero County | Low | 12% | 99% |
| Ouray County | Low | 21% | 96% |
| Park County | Low | 4% | 98% |
| Phillips County | Moderate | 21% | 100% |
| Pitkin County | Low | 23% | 99% |
| Prowers County | Low | 15% | 100% |
| Pueblo County | Low | 19% | 99% |
| Rio Blanco County | Low | 5% | 97% |
| Rio Grande County | Low | 1% | 98% |
| Routt County | Moderate | 37% | 98% |
| Saguache County | Low | 6% | 98% |
| San Juan County | Low | 0% | 83% |
| San Miguel County | Low | 1% | 92% |
| Sedgwick County | Low | 0% | 99% |
| Summit County | Low | 5% | 94% |
| Teller County | Low | 2% | 99% |
| Washington County | High | 40% | 100% |
| Weld County | Low | 21% | 99% |
| Yuma County | Low | 10% | 100% |
* Less than 80% of this county's map acres have completed soil survey data; treat its rating as provisional.
How these ratings are computed
Ratings come from USDA NRCS SSURGO soil survey data: for each soil component we take the maximum linear extensibility percent (lep_r) in the top 100 cm, apply the NRCS Handbook Part 618 class limits (Low under 3 percent, Moderate 3 to 6, High 6 to 9, Very High 9 and above), assign map units by plurality of component percent, and roll acres up to the county. Full details on the methodology section of the lookup page. A county rating is not a parcel-level geotechnical assessment.