O'Brien County, Iowa
The most common soil here is Galva, on about 32% of the land: a silty clay loam, smooth and slightly sticky. Primghar and Marcus come next.
About 36% of the land drains well, and 49% stays wet for long stretches; groundwater comes within two feet of the surface under 49% of it.
USDA rates 99% of the land very limited for a standard septic drain field, and 52% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 9% 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 O'Brien 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/D (varies with drainage). 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 O'Brien 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 |
|---|---|---|---|---|---|
| Galva silty clay loam, 2 to 5 percent slopes | 101K | Well drained | C | Somewhat limited | Very limited |
| Primghar silty clay loam, 0 to 2 percent slopes | 62K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Marcus silty clay loam, 0 to 2 percent slopes | 45K | Poorly drained | C/D | Very limited | Very limited |
| Sac silty clay loam, loam substratum, 2 to 5 percent slopes | 41K | Moderately well drained | C | Somewhat limited | Very limited |
| Primghar silty clay loam, 2 to 5 percent slopes | 37K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Galva silty clay loam, 0 to 2 percent slopes | 12K | Well drained | C | Somewhat 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 |
| Calco silty clay loam, 0 to 2 percent slopes, occasionally flooded | 8K | Poorly drained | C/D | Very limited | Very limited |
| Galva silty clay loam, stratified substratum, 0 to 2 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
| Afton silty clay loam, 0 to 2 percent slopes, occasionally flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Afton silty clay loam, Sheldon creek formation, 0 to 2 percent slopes, occasionally flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Spillco loam, 0 to 2 percent slopes, occasionally flooded | 4K | Moderately well drained | B | Very limited | Very limited |
| Ransom silty clay loam, 1 to 3 percent slopes | 4K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Storden loam, 25 to 40 percent slopes | 4K | Well drained | B | Very limited | Very limited |
| Sac silty clay loam, loam substratum, 5 to 9 percent slopes, eroded | 4K | Moderately well drained | C | Somewhat limited | Very limited |
| Galva silty clay loam, stratified substratum, 2 to 5 percent slopes | 1K | Well drained | C | Somewhat limited | Very limited |
| Storden loam, 18 to 25 percent slopes | 1K | Well drained | B | Very limited | Very limited |
| Fairhaven silt loam, 32 to 40 inches to sand and gravel, 2 to 5 percent slopes | 1K | Well drained | B | Not limited | Very limited |
| Spillville loam, 0 to 2 percent slopes, occasionally flooded | 1K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Terril loam, 5 to 14 percent slopes | 911 | Moderately well drained | B | Somewhat limited | Somewhat 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 52% 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 99% 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.