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Tidal Wetlands Categories

Tidal wetlands are the areas where the land meets the sea. These areas are periodically flooded by seawater during high or spring tides or, are affected by the cyclic changes in water levels caused by the tidal cycle. Salt marshes and mud flats are some typical types of tidal wetlands found along New York's marine shoreline. Tidal wetlands are classified by the amount of water covering the area at high and low tides and the type of vegetation. New York State uses specific categories and codes to describe and represent different types of coastal, tidal and fresh water wetlands. These codes and abbreviations (noted below) are used to identify wetlands on Tidal Wetlands Inventory Maps and help in administering program for their protection.

IM. Intertidal Marsh: The vegetated tidal wetland zone lying generally between average high and low tidal elevation in saline waters. The predominant vegetation in this zone is low marsh cordgrass, Spartina alterniflora. (photo: Down's Creek, Cutchogue, NY)

HM. High Marsh: The normal upper most tidal wetland zone usually dominated by salt meadow grass, Spartina patens; and spike grass, Distichlis spicata. This zone is periodically flooded by spring and storm tides and is often vegetated by low vigor Spartina alterniflora and Seaside lavender, Limonium carolinianum. Upper limits of this zone often include black grass, Juncus Gerardi; chairmaker's rush, Scirpus sp; marsh elder, Iva frutescens; and groundsel bush, Baccharis halimifolia.(Photo: Conscience Bay, Setauket, NY).

FM. Fresh Marsh: The tidal wetland zone found primarily in the upper tidal limits of the riverine systems where significant fresh water inflow dominates the tidal zone. Species normally associated with this zone include narrow leaved cattail, Typha angustifolia; the tall brackish water cordgrass, Spartina pectinata and/or S. cynosuroides; and the more typically emergent fresh water species such as arrow arum, Peltandra; pickerel weed, Pondederia; and cutgrass., Leersia. (Photo: Forge River, Shirley, NY)

FC. Formerly Connected: Lowland areas whose connections to tidal waters are restricted by roadways, dikes, or other man-made facilities. The nature of these tidal wetland areas is widely variable and is a function of the extent of the tidal restriction and the time which has passed since the restriction occurred. Often, Phragmites australis is the dominant vegetation. (Photo: Pickman Remmer Tidal Wetland, Oakdale, NY)

SM. Coastal Shoals, Bars and Mudflats: The tidal wetland zone that at high tide is covered by saline or fresh tidal waters, at low tide is exposed or is covered by water to a maximum depth of approximately one foot, and is not vegetated. (Photo: Huntington Bay, NY)

LZ. Littoral Zone: The tidal wetland zone that includes all lands under tidal waters which are not included in any other category, extending seaward from shore to a depth of six feet at mean low water. (Photo: Great Peconic Bay, NY)

AA. Adjacent Area: Land areas that are adjacent to any of the above tidal wetland zones. These areas are generally not inundated by tidal waters and extend 300 feet landward of the most landward tidal wetlands boundary or to an elevation of ten feet (refer to Part 661 Tidal Wetlands Land Use Regulation).

DS. Dredged Spoil: All areas of fill material identified at the time of the Tidal Wetland Inventory Map creation in 1976. These areas ere generally barren of vegetative cover, diked or contained in some manner, and may not have specifically resulted from a dredging operation; e.g., the fill material may have been removed as part of a subsurface excavation at a nearby building site. In the intervening decades, many of these areas have become revegetated with high marsh and/or upland plant species, depending on current conditions. (Photo: Residential property adjacent to Deep Hole Creek, Mattituck, NY. The mouth of this creek was widened in the 1960s and the resulting dredged sand was used to fill the adjacent marshland. Over time, some trees and grass have become established but the sandy substrate is still readily apparent.)