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Tidal Wetlands

The final Tidal Wetlands Guidance document for installing catwalks and docks is listed in the right column of this page.

picture of a tidal wetland

A typical tidal wetland is the salt marsh which is found in the near shore areas all around Long Island, the lower Hudson River, and along the entire Atlantic coast of the United States. These areas are dominated by grasses and other marsh plants which are adapted to the rise and fall of the tide and the salty water it brings. The blades of marsh grass provide a hiding place for many juvenile fish and habitat for many other animals as well. The grass blades become a vital part of the food chain when they break off and decay, providing food for detritivores (animals that eat decaying organic material) and nutrients to the marine environment. Tidal wetlands in New York State are found on the Hudson River from the Troy Dam south to the southern tip of Staten Island, and along the entire shoreline of Long Island, including the shorelines of Gardiners Island, Shelter Island and Fishers Island.

tidal wetland map

New York State recognized the importance of this unique habitat and sought to insure its protection from filling and dredging--human activities that had drastically reduced the amount of tidal wetlands in New York by passing the Tidal Wetland Act in 1973. In 1974 DEC collected a set of aerial infrared photographs of all the tidal wetlands on Long Island and along the lower Hudson River. Using these photographs, DEC established the New York State Official Tidal Wetlands Inventory, a set of maps delineating and classifying all the tidal wetlands in New York. These maps are used by DEC and other municipal agencies to control and manage the development, filling and dredging of areas in and around New York's valuable tidal wetlands. This Inventory is also available to the general public to examine. Many individuals wish to consult these maps before undertaking any building or landscaping along the shoreline. The statutory definition of a tidal wetland can be found in New York's Environmental Conservation Law, Article 25, entitled "Tidal Wetlands Act."

The New York State Official Tidal Wetlands Inventory is maintained by DEC Bureau of Marine Resources in the Tidal Wetlands Inventory and Geographic Information System (GIS) Unit. To properly evaluate the effectiveness of DEC's tidal wetlands program in protecting total acres of wetlands, a tidal wetlands trends analysis (TWTA) was conducted in certain tidal areas of New York State. In each area total acres of each tidal wetlands category, such as high marsh, intertidal marsh and fresh marsh were determined. Site visits to each tidal wetland area and detailed examinations of 1989 aerial photography were used to determine the acreage of the tidal wetland categories. These results were compared to the Official New York State Tidal Wetlands Inventory based on 1974 aerial infrared photography. Some of the areas examined during this analysis include Shinnecock and Moriches Bays in Suffolk County on Long Island.

Trends

The first area studied, Shinnecock Bay, showed a gain of 161 acres of tidal wetlands as a result of a landward movement of the tidal wetlands boundary from 1974 to 1995. Twenty-one acres of tidal wetlands were destroyed by natural causes. Of the 21 acres destroyed, 15 acres of tidal wetlands on islands were destroyed. Six of the original 13 tidal wetlands islands were destroyed. The loss of wetlands to permitted and unpermitted human activities was too small to be detected. The main cause of wetlands destruction has shifted from human caused factors such as filling to natural factors such as storms and flow restrictions. The DEC tidal wetlands program has been successful in protecting wetlands in this area.

Moriches Bay showed a gain of approximately 100 acres of tidal wetlands as a result of a landward movement of the tidal wetlands boundary from 1974 to 1998. Two and one half acres of tidal wetlands were destroyed by natural causes. The loss of wetlands to permitted and un-permitted human activities was too small to be detected. The main cause of wetlands destruction has shifted from human caused factors, such as filling, to natural factors, such as storms and flow restrictions. The DEC tidal wetlands program has been successful in protecting wetlands in this area, too.

Quantuck Bay and Moneybogue Pond were other areas that were studied as a part of these trend analyses.


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