St. Mary Parish, Louisiana

Survey Area LA101• Louisiana

The dominant drainage class is Very poorly drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil. 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. 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
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

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.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

Vertisols

High-clay soils that shrink and swell dramatically. Fertile but challenging for foundations and septic systems.

Histosols

Organic peat and muck soils formed in wetlands. Very poor for building (compressible) and septic. Often in regulated wetlands.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

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.