Plymouth County, Iowa
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). 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 Plymouth County, Iowa.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Galva silty clay loam, 5 to 9 percent slopes, eroded | 129K | Well drained | C | Somewhat limited | Very limited |
| Galva silty clay loam, 2 to 5 percent slopes | 110K | Well drained | C | Somewhat limited | Very limited |
| Radford silty clay loam, 2 to 5 percent slopes | 44K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Ida silt loam, 9 to 14 percent slopes, severely eroded | 43K | Well drained | B | Somewhat limited | Somewhat limited |
| Ida silt loam, 14 to 20 percent slopes, severely eroded | 23K | Well drained | B | Very limited | Very limited |
| Galva silty clay loam, terrace, 2 to 5 percent slopes | 22K | Well drained | C | Somewhat limited | Very limited |
| McPaul-Kennebec silt loams, 2 to 5 percent slopes | 18K | Moderately well drained | B | Very limited | Very limited |
| Ida silt loam, 5 to 9 percent slopes, severely eroded | 16K | Well drained | B | Not limited | Somewhat limited |
| Kennebec silt loam, 0 to 2 percent slopes, occasionally flooded | 14K | Moderately well drained | B | Very limited | Very limited |
| Colo silty clay loam, deep loess, 0 to 2 percent slopes, occasionally flooded | 11K | Poorly drained | C/D | Very limited | Very limited |
| Kennebec-McPaul silt loams, 2 to 5 percent slopes | 11K | Moderately well drained | B | Very limited | Very limited |
| Ida silt loam, 20 to 30 percent slopes, severely eroded | 11K | Well drained | B | Very limited | Very limited |
| Galva silty clay loam, 9 to 14 percent slopes, eroded | 10K | Well drained | C | Somewhat limited | Very limited |
| Monona silt loam, 5 to 9 percent slopes, eroded | 9K | Well drained | B | Not limited | Somewhat limited |
| Primghar silty clay loam, 2 to 5 percent slopes | 9K | Somewhat poorly drained | C/D | Very limited | Very limited |
| McPaul silt loam, 0 to 2 percent slopes | 8K | Moderately well drained | B | Very limited | Very limited |
| Radford silty clay loam, 0 to 2 percent slopes | 8K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Napier silt loam, 5 to 9 percent slopes | 6K | Well drained | B | Not limited | Somewhat limited |
| Monona silt loam, 9 to 14 percent slopes, eroded | 6K | Well drained | B | Somewhat limited | Somewhat limited |
| Napier-Castana silt loams, 9 to 14 percent slopes | 5K | Well drained | B | Somewhat limited | Somewhat limited |
What This Means
Building & Foundations
About 30% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 83% 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.