The following is a map unit description from the "Soil Survey of Norfolk and Suffolk Counties, Massachusetts (Peragallo, 1989)"
Sa-Saco silt loam. This is a very deep, nearly level, very poorly drained soil on the lowest lying parts of flood plains adjacent to streams and rivers. Areas of the soil are irregular in shape and range from 6 to 250 acres.
Typically, the surface layer is 26 inches thick. It is very dark grayish brown silt loam in the upper part and black silt loam in the lower part. The substratum extends to a depth of 60 inches or more. It is very dark gray and grayish brown silt loam in the upper part and grayish brown loamy fine sand in the lower part.
Included with this soil in mapping are small areas of Freetown soils, ponded, and Rippowam, Scarboro, and Swansea soils in similar positions on the landscape. Included areas make up about 15 percent of the map unit.
Permeability: Moderate in the surface layer and the subsoil and rapid in the substratum.
Available water capacity: High.
Soil reaction: Strongly acid or moderately acid throughout.
Depth to bedrock: More than 60 inches.
Depth to the seasonal high water table: 0 to 0.5 foot.
Hydrologic group: D.
Flooding: Frequent for long periods.
Most areas of this soil are used as habitat for wetland wildlife and support a growth of sedges, wetland shrubs, and grasses.
This soil is very poorly suited to crop production or pasture because of flooding and the seasonal high water table.
Potential productivity for eastern white pine on this soil is moderately high. Management concerns are flooding. the seasonal high water table, high seedling mortality, and the hazard of windthrow. Some areas are suitable for hand-planting of trees.
This soil is generally not suited to use as sites for buildings and septic tank absorption fields because of flooding and the seasonal high water table. Soils that are better suited to these uses are generally nearby. Constructing roads on raised, coarse textured fill material and providing adequate side ditches and culverts help to prevent damage to the pavement by flooding.
This soil is best suited to use as habitat for wetland wildlife. Extensive areas along the Charles and Neponset Rivers are publicly owned and controlled and are used for hunting and other outdoor recreation.
This soil. is in capability subclass VIw.