There are an estimated 25 to 50 extant occurrences statewide. The several documented occurrences have good viability and most are protected on public land or private conservation land. The community is restricted to sheltered areas of the seacoast in the Coastal Lowlands and Manhattan Hills ecozones, and includes a few moderate sized, good quality examples. The current trend of the community is declining. Substantial primary threats, common to all salt marsh complexes, include ditching and draining, dredging and filling, common reed (Phragmites australis) invasion, poor water quality, diking and impoundment, inlet stabilization, shoreline hardening, wrack accumulation, altered sediment budget, subsidence, changes in water circulation patterns, restricted tidal connection, and altered tidal hydrodynamics.

In recent decades, particularly since 1922, the number, aerial extent, and quality of high salt marshes in New York has declined significantly. It is speculated that these losses are linked to the public works projects of the 1930s, including dredging and filling for major airport construction and urban development. Because high salt marshes are drier, closer to uplands, and easier to fill than low salt marshes, they are thought to have been disproportionately affected (Nixon 1982, O'Connor and Terry 1972). Declines have also been due to ditching for mosquito control; production of salt hay as a forage crop for livestock; and to pollution, including airborne particulates, pesticides, and sewage and stormwater discharge. It is suspected that losses will continue, resulting from ongoing shoreline development, declining water quality, and hydrologic alterations.

The number, aerial extent, and integrity of high salt marshes in New York are suspected to have declined substantially from their historical state. These declines are likely correlated with coastal development, ditching, filling, and changes in hydrology, water quality, and natural processes. Since the mid-1600's, high salt marshes in New England (presumably in New York) have been flooded, drained, impounded, diked, ditched, filled, used to produce forage crops (salt hay) for livestock, and/or extirpated by development (Nixon 1982).