DEEP: Types of Wetlands

Inland and Tidal Wetlands

Inland Wetlands and Watercourses   |   Tidal Wetlands

Though wetlands are commonly identified using the familiar terms marsh, swamp, river, brook, pond or lake, Connecticut has very specific legal definitions for inland wetlands and tidal wetlands.  Note: Other states and federal agencies may use different definitions for wetlands.

Inland Wetlands and Watercourses

Inland wetlands are defined by soil type.  The soil types of wetlands are poorly drained, very poorly drained, alluvial and floodplain.  Wetlands may not always appear wet.  For example, all floodplain soils are considered wetlands regardless of drainage class.  Areas disturbed by human activities and no longer in their natural state, may also be classified as wetlands due to their soil characteristics.  Identifying wetlands by soils allows us to identify wetlands during times of drought when characteristic wetland indicator plants may not be obvious.

Poorly drained soils occur where the water table is at or just below the ground surface, usually from late fall to early spring. The land where poorly drained soils occur is nearly level or gently sloping.  Many of our red maple swamps are on these soils.

Very poorly drained soils generally occur on level land or in depressions. In these areas, the water table lies at or above the surface during most of the growing season.  Most of our marshes and bogs are on these soils.

Alluvial and floodplain soils occur along watercourses occupying nearly all level area subject to periodic flooding. These soils are formed when material is deposited by flowing water.  Such material can be composed of clay, silt, sand or gravel.  Alluvial and floodplain soils range from excessively drained to very poorly drained.

Watercourses are defined broadly to mean rivers, streams, brooks, waterways, lakes, ponds, marshes, swamps, bogs and all other bodies of water, natural or artificial, vernal or intermittent, public or private.

Tidal Wetlands

Tidal wetlands are flat, vegetated areas that are subject to regular flooding by the tides. Typically found along the shore and estuaries of Long Island Sound, tidal wetlands also occur further upstream along tidally influenced rivers and their tributaries. Although tidal, they are not necessarily associated with salt water, and can support freshwater or brackish vegetation. 

The most familiar form of tidal wetland, and a defining feature of Connecticut’s shoreline landscape, is the coastal salt marsh characterized by such plants as salt marsh cordgrass (Spartina alterniflora), salt meadow cordgrass (Spartina patens) and spikegrass (Distichlis spicata).