Freshwater wetlands play a significant role in the ecology of Suffolk County, New York. These unique ecosystems support a variety of plants and animals including several at risk species, such as the State endangered eastern tiger salamander and State threatened banded sunfish. Wetlands are generally described as those areas where water and land meet to create highly productive habitats that support a wide range of species adapted to survive in the wet/dry cycles. Wetlands are further classified by the amount of salinity found within their waters. Freshwater wetlands are often defined by vegetation and soil types, indicative of moisture laden, non-saline environments.

Tidal freshwater wetlands are those wetlands that are found at the mouths of large tidal rivers. The boundaries between fresh and saltwater wetlands in these systems are often difficult to define and are constantly changing due to the influence of tidal cycles and influxes in freshwater inputs. In most cases, these wetlands are identified by vegetation and soil types due to the fact that they exhibit less variability than salinities and animal species present. Freshwater tidal communities are divided into two categories: low elevation, broad leaf emergent zones; and, higher, graminoid (grass-like plant) zones.

Riverine systems are defined as riverside wetlands and deeper water habitats contained within a channel and are generally classified by water flow rates, substrate composition, and faunal and vegetative species present. Classes of vegetation found in riverine systems include:

· Emergent and submergent bryophytes
· Hydrophytic vascular plants
· Submergent vegetation

Lacustrine communities are defined as those freshwater wetlands and deeper water habitats situated in topographical depressions or dammed river channels. Lakes and ponds are characteristic of this group and are identified by low directional flow and characteristic life such as algae, pickerel, tiger salamanders and muskrats

Palustrine wetlands include a variety of freshwater swamps, marshes and bogs. These communities are often dominated by a variety of trees, shrubs, persistent emergents, emergent mosses and lichens.