FOR IMMEDIATE RELEASE99-93
December
17, 1999
Contact:
Geoff Ryan
(718/595-5371)
Wetland
Reports Released
The United States Fish & Wildlife Service (USFWS) has completed
two reports for the New York City Department of Environmental Protection
(DEP) that review wetland conditions over the last 30 years in the
watersheds of the City's East-of-Hudson reservoirs. "Wetland
Trends in the Croton Watershed, New York: 1960s to 1990s" traces
the changes in wetland types, as well as wetland gains and losses
in the 387-square-mile watershed during two periods 1968-1984
and 1984-1994. From 1968 to 1984, the annual net loss of vegetated
wetlands averaged 9.1 acres per year. During the 1984-1994 period,
the rate dropped to 4.3 acres per year. Over the 26-year period, approximately
190 acres of vegetated wetlands were converted to uplands or ponds.
Primarily as a result of residential development, almost 100 acres
of the lost wetlands, 90 of which were forested, were converted to
shallow, open- water ponds. The 190-acre loss represents 1.2 percent
of the wetlands that existed at the start of the study period in 1968.
Although ponds perform some important water quality functions, it
is not known how the increase in ponds at the expense of vegetated
wetlands has affected water quality in the Croton Watershed. It is
known, however, that vegetated wetlands provide significant benefits
filtering pollutants from the waters that flow into wetlands
from surrounding uplands; slowing the flow of waters, which reduces
soil erosion and other impacts of storms and floods; and nutrient
cycling, which reduces nitrogen and phosphorus loads in the reservoirs.
The second report, "Wetland Characterization and Preliminary
Assessment of Wetland Functions for the Boyd Corners and West Branch
Sub-basins of the Croton Watershed," is technical in nature and
presents a preliminary strategy for assessing wetland functions. As
such, it is a progress report that outlines a remote sensing approach
to wetland functional assessment that was recently developed by USFWS
and implemented as a pilot study in the West Branch and Boyd Corners
Reservoir sub-basins. USFWS interpreted maps and aerial photography
to classify wetlands according to their landscape setting, land form
and hydrologic flow paths. Wetland classifications were verified by
field checking and then used to provide a preliminary evaluation of
eight wetland functions: surface water retention, streamflow maintenance,
nutrient cycling, sediment and particulate retention, shoreline stabilization,
and habitat for fish, waterfowl, waterbirds and other wildlife. Maps
were then produced that differentiate wetlands based on their potential
to perform specified functions at significant levels.
This preliminary report will serve as the basis for further study
by DEP scientists who will verify and quantify the water quality functions
of wetlands in two pilot sub-basins. Assessment of wetland functions
will help DEP develop wetland protection and non-point source pollution
prevention programs, quantify the roles of wetlands for water quality
modeling, provide guidance for regulatory permit decisions, and help
to direct management of the City's own watershed wetlands.
In 1997, DEP published another USFWS study, "Wetlands in the
Watersheds of the New York City Water Supply System: Results of the
National Wetlands Inventory," which describes the variety and
status of wetlands in both the East-of-Hudson and West-of-Hudson watersheds
of the New York City Water Supply System. Copies of all three reports
are available by phoning 914/773- 4422.