41 counties mapped. On average, 22% of California county soil area is high shrink-swell clay (USDA SSURGO).
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Get repair quotes →| County | Tier | High-risk % | Moderate % |
|---|---|---|---|
| Colusa | Severe | 53% | 18% |
| Solano | Severe | 51% | 16% |
| Modoc | Severe | 49% | 17% |
| Yolo | Severe | 48% | 22% |
| Contra Costa | Severe | 46% | 21% |
| Imperial | Severe | 44% | 16% |
| Sutter | Severe | 43% | 20% |
| Alameda | Severe | 37% | 3% |
| Sacramento | Severe | 36% | 20% |
| Kings | Severe | 35% | 23% |
| Merced | Severe | 34% | 28% |
| Glenn | Severe | 34% | 18% |
| San Joaquin | Severe | 32% | 24% |
| Fresno | Severe | 30% | 38% |
| Stanislaus | High | 26% | 28% |
| Sonoma | High | 24% | 46% |
| Marin | High | 22% | 10% |
| Yuba | High | 22% | 34% |
| Santa Barbara | High | 21% | 17% |
| San Benito | High | 19% | 30% |
| Tehama | High | 17% | 24% |
| San Luis Obispo | High | 17% | 28% |
| Tulare | High | 16% | 30% |
| Placer | Moderate | 15% | 21% |
| Siskiyou | Moderate | 14% | 22% |
| San Diego | Moderate | 14% | 15% |
| Monterey | Moderate | 14% | 20% |
| Napa | Moderate | 13% | 35% |
| Shasta | Moderate | 11% | 30% |
| Humboldt | Moderate | 10% | 33% |
| Santa Cruz | Moderate | 10% | 40% |
| Kern | Moderate | 9% | 28% |
| Lake | Moderate | 9% | 27% |
| Los Angeles | Moderate | 8% | 14% |
| Mariposa | Moderate | 6% | 28% |
| Nevada | Low | 5% | 48% |
| Trinity | Low | 3% | 8% |
| Mendocino | Low | 2% | 45% |
| Riverside | Low | 2% | 2% |
| San Bernardino | Low | 1% | 18% |
| Inyo | Low | 0% | 2% |
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.