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PLYMOUTH COUNTY, MASSACHUSETTS SOIL SURVEY UPDATE 1 - Water This map unit consists of water bodies including ponds, lakes, and reservoirs. It also consists of areas of moving water such as streams and rivers that were wide enough to be delineated as a map unit. Most of this unit is perennially covered with water more than 3 feet deep but some areas may become dry during droughts and when used for human activity such as reservoirs and cranberry bed management activities. The shoreline boundary of the map unit is subject to fluctuations caused by seasonal variations and surrounding land uses. This map unit ranges from less than 2 acres to more than 3,000 acres of Assawompset Pond. Included in this map unit are areas of emergent vegetation, Freetown and Swansea soils, and small islands consisting of upland soil, bedrock or glacial deposits. This map unit is used for areas of open water bodies created by human activity. They typically consists of ponds and lagoons used for industrial purposes such as sewage treatment plants, sediment settling ponds, and storm water detention basins. The water level is typically regulated by human and natural causes and may become dry for periods of time. Included with this unit are areas of Udorthents, which consists of fill material used as dikes and Urban land. This map unit consists of streams, rivers, ponds, and lakes influenced by salt water and/or subject to tidal inundation. These water bodies may be adjacent to soil map units influenced by the same noted factors and include Hooksan, Ipswich, Pawcatuck, and Matunuck soils and areas of beaches and tidal flats. Streams and rivers large enough to be delineated as polygons have been classified as either fresh water (map unit 1) or saline-influenced (map unit 607). Where streams and rivers transition from salt and/or brackish to fresh water, surrounding soil map units and/or wetlands were used as indicators to separate fresh from salt water. Coastal ponds may have salt water if adjacent to tidal marshes, beaches, or the ocean and/or if subject to tidal inundation by an open channel of flowing water from a salt water source. Resources used to determine water salinity were provided by the Massachusetts Geographic Information System (MassGIS) 1:5000 wetlands data layer, providing delineation of fresh water and salt water wetlands, and the NRCS soil survey. The saline-influenced water units (map unit 607) correspond with the MassGIS "salt water marsh" or "tidal flat" wetlands, and/or the Ipswich, Pawcatuck, and Matunuck soil map unit(s) in this soil survey. This map unit consists of salt water areas of bays, harbors, inlets, and open ocean. The map unit is used to define the boundary separating terrestrial land soil map units and areas of beaches, tidal-influenced water bodies that are delineated as water, saline (map unit 607) and tidal flats. Included in this unit are small bedrock islands, shoals, and bars that form temporarily as a result of a depositional event. |
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