Carroll County, Iowa
The most common soil here is Marshall, on about 20% of the land: a silty clay loam, smooth and slightly sticky. Clarion and Colo come next.
About 58% of the land drains well, and 41% stays wet for long stretches; groundwater comes within two feet of the surface under 43% of it.
USDA rates 81% of the land very limited for a standard septic drain field, and 45% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 22% of the land floods occasionally or more.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Carroll County, Iowa, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. 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 Carroll County, Iowa. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Colo-Judson silty clay loams, 0 to 5 percent slopes, occasionally flooded | 40K | Poorly drained | C/D | Very limited | Very limited |
| Clarion loam, Bemis moraine, 2 to 6 percent slopes | 28K | Well drained | B | Somewhat limited | Somewhat limited |
| Nicollet loam, 1 to 3 percent slopes | 28K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Marshall silty clay loam, 5 to 9 percent slopes, eroded | 26K | Well drained | C | Somewhat limited | Very limited |
| Marshall silty clay loam, 2 to 5 percent slopes, eroded | 20K | Well drained | C | Somewhat limited | Very limited |
| Marshall silty clay loam, 9 to 14 percent slopes, eroded | 20K | Well drained | C | Somewhat limited | Very limited |
| Clarion loam, Bemis moraine, 6 to 10 percent slopes, moderately eroded | 18K | Well drained | B | Somewhat limited | Somewhat limited |
| Exira silty clay loam, 5 to 9 percent slopes, eroded | 18K | Well drained | C | Somewhat limited | Very limited |
| Exira silty clay loam, 9 to 14 percent slopes, eroded | 18K | Well drained | C | Somewhat limited | Very limited |
| Webster clay loam, Bemis moraine, 0 to 2 percent slopes | 17K | Poorly drained | C/D | Very limited | Very limited |
| Canisteo clay loam, Bemis moraine, 0 to 2 percent slopes | 14K | Poorly drained | C/D | Very limited | Very limited |
| Marshall silty clay loam, 2 to 5 percent slopes | 10K | Well drained | C | Somewhat limited | Very limited |
| Colo silt loam, deep loess, 0 to 2 percent slopes, overwash, occasionally flooded | 9K | Poorly drained | C/D | Very limited | Very limited |
| Clarion loam, Bemis moraine, 2 to 6 percent slopes, moderately eroded | 9K | Well drained | B | Somewhat limited | Somewhat limited |
| Ackmore silt loam, 0 to 2 percent slopes, occasionally flooded | 6K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Calco silty clay loam, 0 to 2 percent slopes, occasionaly flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Coland clay loam, 0 to 2 percent slopes, occasionally flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Colo silty clay loam, deep loess, 0 to 2 percent slopes, occasionally flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Okoboji silty clay loam, 0 to 1 percent slopes | 4K | Very poorly drained | C/D | Very limited | Very limited |
| Coland-Spillville complex, 2 to 5 percent slopes | 4K | Poorly drained | C/D | Very limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 45% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 81% 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
Drainage is generally favorable for gardening. Adding compost and mulch will improve fertility and water retention. Test your soil's pH before planting — most vegetables prefer 6.0-7.0.