Frio County, Texas
The most common soil here is Duval, on about 22% of the land: a very fine sandy loam, gritty and crumbly. Webb and Zavco come next.
About 93% of the land drains well.
USDA rates 65% of the land very limited for a standard septic drain field, and 25% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 13% of the land floods occasionally or more, and bedrock lies within 40 inches under 3% of it.
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 Frio County, Texas, 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 Frio County, Texas. 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 |
|---|---|---|---|---|---|
| Duval very fine sandy loam, 1 to 3 percent slopes | 106K | Well drained | B | Not limited | Somewhat limited |
| Hindes-Yologo complex, 1 to 8 percent slopes | 61K | Well drained | C | Not limited | Very limited |
| Duval loamy fine sand, 0 to 5 percent slopes | 53K | Well drained | B | Not limited | Somewhat limited |
| Webb very fine sandy loam, 1 to 3 percent slopes | 52K | Well drained | C | Somewhat limited | Very limited |
| Zavco sandy clay loam, 1 to 3 percent slopes | 26K | Well drained | C | Somewhat limited | Very limited |
| Poteet very fine sandy loam, occasionally flooded | 26K | Moderately well drained | C | Very limited | Very limited |
| Brystal very fine sandy loam, 1 to 3 percent slopes | 25K | Well drained | B | Not limited | Somewhat limited |
| Uvalde clay loam, 0 to 1 percent slopes | 24K | Well drained | C | Somewhat limited | Very limited |
| Duval very fine sandy loam, 0 to 1 percent slopes | 21K | Well drained | B | Not limited | Somewhat limited |
| Poth loamy fine sand, 0 to 3 percent slopes | 19K | Well drained | C | Somewhat limited | Very limited |
| Zavco sandy clay loam, 0 to 1 percent slopes | 18K | Well drained | C | Somewhat limited | Very limited |
| Winterhaven silty clay loam, occasionally flooded | 14K | Well drained | B | Very limited | Very limited |
| Dilley fine sandy loam, 1 to 5 percent slopes | 13K | Well drained | D | Very limited | Very limited |
| Webb very fine sandy loam, 0 to 1 percent slopes | 13K | Well drained | C | Somewhat limited | Very limited |
| Elmendorf-Denhawken complex, 1 to 3 percent slopes | 12K | Well drained | D | Very limited | Very limited |
| Miguel very fine sandy loam, 1 to 3 percent slopes | 11K | Well drained | C | Somewhat limited | Very limited |
| Caid sandy clay loam, 1 to 3 percent slopes | 11K | Well drained | B | Not limited | Somewhat limited |
| Caid sandy clay loam, 0 to 1 percent slopes | 11K | Well drained | B | Not limited | Somewhat limited |
| Lacoste very fine sandy loam, 1 to 5 percent slopes | 11K | Well drained | D | Very limited | Very limited |
| Olmos very cobbly loam, 1 to 8 percent slopes, rubbly | 11K | Well drained | 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 25% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 65% 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.