Starr County, Texas
The most common soil here is McAllen, on about 30% of the land: a fine sandy loam, gritty and crumbly. Copita and Zapata come next.
About 88% of the land drains well.
USDA rates 51% of the land very limited for a standard septic drain field, and 40% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 8% of the land floods occasionally or more, and bedrock lies within 40 inches under 15% 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 Starr 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 B (moderate infiltration). The most common soil order is Entisols — young soils with little profile development, often on floodplains or steep slopes. 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 Starr 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 |
|---|---|---|---|---|---|
| McAllen fine sandy loam | 237K | Well drained | B | Not limited | Somewhat limited |
| Copita fine sandy loam, 0 to 3 percent slopes | 113K | Well drained | C | Somewhat limited | Very limited |
| Brennan fine sandy loam, 0 to 1 percent slopes | 65K | Well drained | B | Not limited | Somewhat limited |
| Zapata soils | 60K | Well drained | D | Very limited | Very limited |
| Catarina clay, association, 0 to 5 percent slopes | 53K | Moderately well drained | D | Very limited | Very limited |
| Ramadero loam | 43K | Well drained | B | Very limited | Very limited |
| Delmita fine sandy loam, 0 to 3 percent slopes | 37K | Well drained | C | Very limited | Very limited |
| Garceno clay loam | 28K | Well drained | B | Very limited | Somewhat limited |
| Sarita fine sand, 0 to 5 percent slopes | 26K | Well drained | A | Not limited | Somewhat limited |
| Jimenez-Quemado association | 23K | Well drained | D | Very limited | Very limited |
| Montell clay, 0 to 3 percent slopes | 20K | Moderately well drained | D | Very limited | Very limited |
| Delmita and Bruni soils, 0 to 3 percent slopes | 16K | Well drained | C | Very limited | Very limited |
| Reynosa silty clay loam | 8K | Well drained | B | Somewhat limited | Somewhat limited |
| Comitas loamy fine sand, 0 to 3 percent slopes | 7K | Well drained | A | Not limited | Not limited |
| Rio Grande silt loam, 0 to 1 percent slopes | 7K | Well drained | A | Very limited | Very limited |
| Lagloria silt loam | 7K | Well drained | B | Not limited | Somewhat limited |
| Matamoros silty clay | 5K | Moderately well drained | C | Very limited | Very limited |
| Camargo silty clay loam, 0 to 1 percent slopes, rarely flooded | 5K | Well drained | B | Very limited | Somewhat limited |
| Falfurrias fine sand, 0 to 5 percent slopes | 4K | Somewhat excessively drained | A | Not limited | Very limited |
| Water | 4K | D | Not rated | Not rated |
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 40% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 51% 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.