St. Mary Parish, Louisiana
The dominant drainage class is Very poorly drained and the dominant hydrologic group is D (very slow infiltration, high runoff). 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 St. Mary Parish, Louisiana.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Water | 44K | Not rated | Not rated | ||
| Maurepas muck, 0 to 1 percent slopes, frequently flooded | 44K | Very poorly drained | A/D | Very limited | Very limited |
| Baldwin silty clay loam, 0 to 1 percent slopes | 42K | Poorly drained | D | Very limited | Very limited |
| Kenner muck, 0 to 1 percent slopes, very frequently flooded | 41K | Very poorly drained | D | Very limited | Very limited |
| Barbary muck, 0 to 1 percent slopes, frequently flooded | 38K | Very poorly drained | D | Very limited | Very limited |
| Larose muck, 0 to 0.5 percent slopes, tidal | 29K | Very poorly drained | C/D | Very limited | Very limited |
| Iberia clay, 0 to 1 percent slopes | 25K | Poorly drained | D | Very limited | Very limited |
| Allemands muck, 0 to 0.2 percent slopes, very frequently flooded | 25K | Very poorly drained | A/D | Very limited | Very limited |
| Aquents, dredged, 1 to 5 percent slopes, occasionally flooded | 20K | Very poorly drained | D | Not rated | Not rated |
| Schriever clay, 0 to 1 percent slopes, rarely flooded | 17K | Poorly drained | D | Very limited | Very limited |
| Balize silt loam, very frequently flooded | 15K | Very poorly drained | C/D | Very limited | Very limited |
| Hydraquents, Carville, and Glenwild soils, undulating, flooded | 14K | Very poorly drained | C | Very limited | Very limited |
| Schriever clay, 0 to 1 percent slopes, frequently flooded | 13K | Poorly drained | D | Very limited | Very limited |
| Carville and Hydraquents soils, undulating, flooded | 12K | Somewhat poorly drained | C | Very limited | Very limited |
| Galvez silt loam, 0 to 1 percent slopes | 11K | Somewhat poorly drained | C | Very limited | Very limited |
| Harahan and Allemands soils, drained | 8K | Poorly drained | D | Very limited | Very limited |
| Harahan clay, 0 to 1 percent slopes | 8K | Poorly drained | D | Very limited | Very limited |
| Uderts and Glenwild soils, 0 to 3 percent slopes, smoothed | 6K | Somewhat poorly drained | D | Very limited | Very limited |
| Fausse soils, 0 to 1 percent slopes, frequently flooded | 5K | Very poorly drained | C/D | Very limited | Very limited |
| Clovelly muck, 0 to 0.2 percent slopes, very frequently flooded | 4K | Very poorly drained | C/D | Very limited | Very limited |
What This Means
Building & Foundations
About 84% 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 84% of soils are rated "very limited" for septic absorption fields. Poorly drained soils can't absorb septic effluent effectively. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Many soils hold water for extended periods. Raised beds are highly recommended to improve drainage for vegetables. Well-adapted native plants and water-loving species will do best in natural conditions.