Lamar and Delta Counties, Texas
The most common soil here is Houston Black, on about 9% of the land: a clay, sticky when wet and rock-hard when dry. Wilson and Annona come next.
About 21% of the land drains well, and 10% stays wet for long stretches; groundwater comes within two feet of the surface under 16% of it.
USDA rates 90% of the land very limited for a standard septic drain field, and 81% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 17% of the land floods occasionally or more, and bedrock lies within 40 inches under 2% 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 Lamar and Delta Counties, 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 Moderately well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Vertisols — clay-rich soils that shrink and swell dramatically with moisture changes. 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 Lamar and Delta Counties, 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 |
|---|---|---|---|---|---|
| Houston Black clay, 1 to 3 percent slopes | 76K | Moderately well drained | D | Very limited | Very limited |
| Annona loam, 1 to 4 percent slopes | 58K | Moderately well drained | D | Very limited | Very limited |
| Freestone-Hicota complex, 0 to 3 percent slopes | 58K | Moderately well drained | C | Somewhat limited | Very limited |
| Wilson silt loam, 0 to 2 percent slopes | 50K | Moderately well drained | D | Very limited | Very limited |
| Leson clay, 1 to 3 percent slopes | 45K | Moderately well drained | D | Very limited | Very limited |
| Crockett loam, 1 to 3 percent slopes | 36K | Moderately well drained | D | Very limited | Very limited |
| Woodtell loam, 5 to 12 percent slopes | 28K | Well drained | D | Very limited | Very limited |
| Normangee clay loam, 1 to 3 percent slopes | 25K | Moderately well drained | C | Very limited | Very limited |
| Water | 25K | D | Not rated | Not rated | |
| Normangee clay loam, 2 to 5 percent slopes, eroded | 24K | Moderately well drained | C | Very limited | Very limited |
| Trinity clay, 0 to 1 percent slopes, occasionally flooded | 24K | Moderately well drained | D | Very limited | Very limited |
| Whakana-Porum complex, 8 to 20 percent slopes | 21K | Well drained | B | Somewhat limited | Somewhat limited |
| Heiden clay, 2 to 5 percent slopes | 19K | Well drained | D | Very limited | Very limited |
| Trinity clay, 0 to 1 percent slopes, frequently flooded | 18K | Moderately well drained | D | Very limited | Very limited |
| Derly, occasionally ponded-Raino complex, 0 to 1 percent slopes | 16K | Poorly drained | D | Very limited | Very limited |
| Deport clay, 1 to 3 percent slopes | 16K | Somewhat poorly drained | D | Very limited | Very limited |
| Kaufman clay, 0 to 1 percent slopes, frequently flooded | 15K | Moderately well drained | D | Very limited | Very limited |
| Whakana fine sandy loam, 1 to 5 percent slopes | 15K | Well drained | B | Somewhat limited | Somewhat limited |
| Heiden-Ferris complex, 3 to 5 percent slopes | 15K | Well drained | D | Very limited | Very limited |
| Ferris clay, 5 to 12 percent slopes, eroded | 15K | 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 81% of soils are rated "very limited" for dwellings with basements. Specific challenges include poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 90% 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.