Dallas County, Iowa
The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Dallas County, Iowa.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Clarion loam, Bemis moraine, 2 to 6 percent slopes | 76K | Well drained | B | Somewhat limited | Somewhat limited |
| Canisteo clay loam, Bemis moraine, 0 to 2 percent slopes | 49K | Poorly drained | C/D | Very limited | Very limited |
| Nicollet loam, 1 to 3 percent slopes | 40K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Webster clay loam, Bemis moraine, 0 to 2 percent slopes | 28K | Poorly drained | C/D | Very limited | Very limited |
| Clarion loam, Bemis moraine, 6 to 10 percent slopes, moderately eroded | 23K | Well drained | B | Somewhat limited | Somewhat limited |
| Clarion loam, 2 to 5 percent long slopes | 14K | Well drained | B | Somewhat limited | Somewhat limited |
| Sharpsburg silty clay loam, 5 to 9 percent slopes, eroded | 9K | Moderately well drained | C | Somewhat limited | Very limited |
| Sharpsburg silty clay loam, 2 to 5 percent slopes | 8K | Moderately well drained | C | Somewhat limited | Very limited |
| Coland clay loam, 0 to 2 percent slopes, occasionally flooded | 8K | Poorly drained | C/D | Very limited | Very limited |
| Hayden-Storden loams, 25 to 50 percent slopes | 6K | Well drained | B | Very limited | Very limited |
| Dockery-Quiver silt loams, 0 to 2 percent slopes, occasionally flooded | 5K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Coland-Terril complex, 2 to 5 percent slopes | 5K | Poorly drained | C/D | Very limited | Very limited |
| Hanlon-Spillville complex, channeled, 0 to 2 percent slopes | 5K | Moderately well drained | A | Very limited | Very limited |
| Ladoga silty clay loam, dissected till plain, 5 to 9 percent slopes, eroded | 5K | Moderately well drained | C | Very limited | Very limited |
| Water | 4K | Not rated | Not rated | ||
| Lindley silt loam, 18 to 40 percent slopes | 4K | Well drained | C | Very limited | Very limited |
| Gara-Armstrong complex, 14 to 18 percent slopes | 4K | Somewhat poorly drained | D | Very limited | Very limited |
| Clarion loam, 9 to 14 percent slopes, moderately eroded | 3K | Well drained | B | Somewhat limited | Somewhat limited |
| Lester loam, Bemis moraine, 2 to 6 percent slopes | 3K | Well drained | C | Somewhat limited | Very limited |
| Colo, occasionally flooded-Ely silty clay loams, dissected till plain, 2 to 5 percent slopes | 3K | Poorly drained | C/D | Very limited | Very limited |
What This Means
Building & Foundations
About 53% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 60% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.