60 counties mapped. On average, 36% of South Dakota county soil area is high shrink-swell clay (USDA SSURGO).
Higher percentages mean more of a county's mapped soil is shrink-swell clay that expands and contracts with moisture. This is county-scale exposure, not a diagnosis of any single home — but it tells you whether soil movement belongs on your radar.
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Before you call a foundation company →| County | Tier | High-risk % | Moderate % |
|---|---|---|---|
| Jones | Severe | 94% | 2% |
| Lyman | Severe | 89% | 2% |
| Stanley | Severe | 88% | 2% |
| Haakon | Severe | 88% | 7% |
| Butte | Severe | 74% | 13% |
| Dewey | Severe | 73% | 9% |
| Mellette | Severe | 69% | 16% |
| Gregory | Severe | 65% | 11% |
| Ziebach | Severe | 62% | 14% |
| Fall River | Severe | 58% | 18% |
| Tripp | Severe | 58% | 7% |
| Meade | Severe | 50% | 29% |
| Spink | Severe | 49% | 39% |
| Hyde | Severe | 49% | 46% |
| Jackson | Severe | 49% | 23% |
| Aurora | Severe | 43% | 39% |
| Miner | Severe | 42% | 22% |
| Hughes | Severe | 39% | 45% |
| Beadle | Severe | 38% | 41% |
| Corson | Severe | 36% | 25% |
| Jerauld | Severe | 36% | 28% |
| Hand | Severe | 34% | 57% |
| Brown | Severe | 34% | 46% |
| Douglas | Severe | 33% | 44% |
| Clay | Severe | 31% | 56% |
| Kingsbury | Severe | 30% | 45% |
| Potter | High | 30% | 60% |
| Charles Mix | High | 29% | 53% |
| Edmunds | High | 29% | 66% |
| Sully | High | 29% | 61% |
| Sanborn | High | 28% | 24% |
| Lincoln | High | 28% | 69% |
| Walworth | High | 28% | 56% |
| Roberts | High | 28% | 45% |
| Union | High | 27% | 57% |
| Bon Homme | High | 27% | 30% |
| Grant | High | 27% | 54% |
| Lake | High | 26% | 66% |
| McCook | High | 26% | 18% |
| Faulk | High | 24% | 71% |
| Oglala Lakota | High | 24% | 26% |
| Lawrence | High | 24% | 26% |
| Marshall | High | 23% | 56% |
| Yankton | High | 22% | 33% |
| McPherson | High | 22% | 61% |
| Davison | High | 21% | 35% |
| Perkins | High | 21% | 32% |
| Turner | High | 20% | 47% |
| Clark | High | 19% | 67% |
| Day | High | 19% | 64% |
| Campbell | High | 17% | 52% |
| Minnehaha | Moderate | 15% | 75% |
| Harding | Moderate | 13% | 48% |
| Todd | Moderate | 13% | 16% |
| Hamlin | Moderate | 13% | 71% |
| Deuel | Moderate | 13% | 73% |
| Codington | Moderate | 11% | 71% |
| Brookings | Moderate | 10% | 72% |
| Moody | Moderate | 10% | 84% |
| Bennett | Moderate | 9% | 27% |
Risk metrics are computed from USDA SSURGO soil survey data (linear extensibility of soil components, area-weighted by county). Soil varies lot to lot — this is county-scale context, not a substitute for a site-specific geotechnical or structural assessment.