Tidal and freshwater wetlands were selected from the north and south shores of Suffolk County for study as “Primary Study Areas” (PSAs). These 21 wetlands were chosen because of their exceptional environmental quality or for their value as archetypes for other sites in the County. Each PSA was also important to the County’s vector control program as a known mosquito breeding area, a site managed by the Division of Vector Control, or a control site for the purposes of this project.

An assessment by the Division of Vector Control can be found here. Further information is available in a report entitled Wetlands Classifications - Primary Study Areas. Maps of each of the primary study areas can be viewed or downloaded.

The management of freshwater and estuarine wetlands is a critical component of mosquito control. Historically, marsh ditching was the method of choice to minimize mosquito-breeding habitats. Ditching has been effective in draining some marshes to reduce standing water mosquito breeding areas. However, ditching may have altered marsh hydrology in other ways, along with marsh vegetation patterns, and wildlife habitats. Other methods of marsh management have been proposed for mosquito control that create marsh habitat for mosquito predators and access to these habitats from the tidal creeks. Open Marsh Water Management (OMWM) is one such method that seeks to create fish habitat, often using marsh pools and pannes, plugged ditches, or tidal creek channels and spurs connected to tidal flow. OMWM has been practiced successfully for mosquito control in other regions. One aspect of the study of existing marsh conditions is to make it possible to assess the impacts of OMWM or other marsh management techniques on marsh health.

General descriptions of each marsh were created from public records, aerial photography and maps, and any specific reports published concerning the areas. These descriptions were then augmented by rigorous field observations, made according to an approved plan of study.

A portion of each PSA was studied. At a minimum, the effort included two to four primary ditches, tidal creeks, and upland areas. Observations were recorded for topography, vegetation type, wildlife, waterbodies present (i.e. tidal creeks, ponds and pannes), upland development, and stormwater discharge structures. Temperature, salinity, and dissolved oxygen concentrations were measured in ditches, pannes, ponds, and tidal creeks. Ditch orientation, spacing intervals, occlusions, bank erosion, water movement, depth, and substrate type were recorded. New or full moon tidal inundation was measured. Dominant marsh vegetation was identified and recorded on the aerial maps. Marsh vegetation was identified according to the New York State Department of Environmental Conservation (NYSDEC) zonation designations for intertidal and high marsh, along with areas dominated by the invasive plant, Phragmites australis.