Wetland characterization and preliminary assessment of wetland functions for the Delaware and Catskill watersheds of the New York City water supply system

              Wetland Characterization and Preliminary Assessment of
Wetland Functions for the Delaware and Catskill Watersheds of the
New York City Water Supply System
Produced by the U.S. Fish and Wildlife Service
National Wetlands Inventory Program
Ecological Services, Northeast Region
Hadley, MA
Prepared for New York City Department of Environmental Protection, Valhalla, NY
October 2004 Wetland Characterization and Preliminary Assessment of Wetland Functions
for the Delaware and Catskill Watersheds of
the New York City Water Supply System
By Ralph W. Tiner and Jonathan Stewart
National Wetlands Inventory Program
Ecological Services
U.S. Fish and Wildlife Service
Northeast Region
300 Westgate Center Drive
Hadley, MA 01035
Prepared for New York City Department of Environmental Protection, Valhalla, NY
October 2004 This report should be cited as:
Tiner, R.W. and J. Stewart. 2004. Wetland Characterization and Preliminary Assessment of Wetland Functions for the Delaware and Catsill Watersheds of the New York City Water Supply System. U.S. Fish and Wildlife Service, National Wetlands Inventory, Ecological Services, Region 5, Hadley, MA. Prepared for the New York City Department of Environmental Protection, Valhalla, NY. 50 pp. plus appendices. (Note: Maps in pdf-format are provided on CD version of this report.) Table of Contents
Page
Introduction 1
Study Area 1
Methods 2
Classification and Characterization 2
General Scope and Limitations of Preliminary Functional Assessment 6
Rationale for Preliminary Functional Assessment 7
GIS Analysis and Compilation 11
Maps 11
Results 12
Delaware Watershed 12
Cannonsville Reservoir Basin Profile 12
Wetland Characterization 12
Preliminary Assessment of Wetland Functions 17
Pepacton Reservoir Basin Profile 19
Wetland Characterization 19
Preliminary Assessment of Wetland Functions 23
Neversink Reservoir Basin Profile 25
Wetland Characterization 25
Preliminary Assessment of Wetland Functions 28
Rondout Reservoir Basin Profile 30
Wetland Characterization 30
Preliminary Assessment of Wetland Functions 33
Catskill Watershed 35
Schoharie Reservoir Basin Profile 35
Wetland Characterization 35
Preliminary Assessment of Wetland Functions 39
Ashokan Reservoir Basin Profile 41
Wetland Characterization 41
Preliminary Assessment of Wetland Functions 45
Appropriate Use of this Report 47
Recommendations for Future Studies 47
References 49
Appendices
A. Dichotomous Keys and Mapping Codes for Wetland Landscape Position, Landform, Water Flow Path, and Waterbody Type Descriptors (Tiner 2003a)
B: Correlating Enhanced National Wetlands Inventory Data with Wetland Functions for Watershed Assessments: A Rationale for Northeastern U.S. Wetlands (Tiner 2003b)
Maps (on compact disk-version of report) Introduction
The New York City Water Supply System provides unfiltered drinking water to millions of residents of the City. The significance of wetlands as water sources and natural water filters makes wetland conservation a main area of concern for the New York City Department of Environmental Protection (NYCDEP).
In partnership with the NYCDEP, the U.S. Fish and Wildlife Service (Service) has been inventorying and characterizing wetlands in the NYC Water Supply System since the mid-1990s (Tiner 1997a, Tiner et al. 1999, 2002, 2004). The wetlands inventory characterized wetlands mainly by their vegetation and expected hydrology (water regime), with other modifiers used to indicate human or beaver activities (e.g., diked/impounded, excavated, partly drained, and beaver-influenced). In order to use the inventory data to predict functions (e.g., surface water detention, nutrient transformation, streamflow maintenance, and provision of fish/wildlife habitat), additional information on the hydrogeomorphic characteristics of wetlands is required. The Service has developed a set of attributes to better describe wetlands by landscape position, landform, water flow path, and waterbody type (LLWW descriptors; Tiner 2003a). When added to the National Wetlands Inventory (NWI) data, the enhanced NWI data have a predictive capability regarding wetland functions (Tiner 2003b). The NYCDEP provided funding to the Service to add LLWW descriptors to existing NWI digital data and to produce a preliminary assessment of functions for wetlands in the NYC watersheds. This report documents the findings for the Delaware and Catskill watersheds. The Croton watershed results are presented separately (Tiner et al. 2004).
Study Area
The Delaware and Catskill watersheds are located west of the Hudson River. The Delaware watershed falls largely within Delaware County, with small sections occurring in Greene, Ulster, and Sullivan Counties. This watershed covers over 1,000 square miles. Major rivers and streams draining this watershed are the East and West Branches of the Delaware River and the Neversink River. Four reservoir basins are found in this watershed: Cannonsville, Pepacton, Neversink, and Rondout. The Catskill watershed is mostly in Greene and Ulster Counties with smaller portions in Schoharie and Delaware Counties. It occupies an area about 585 square miles in size containing five major creeks (Schohaire Creek, Esopus Creek, Stony Creek, Batavia Kill, and Rondout Creek) and two reservoir basins: Schoharie and Ashokan.
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Methods
Classification and Characterization
The purpose of this project was to enhance the existing NWI dataset by adding LLWW attributes to each mapped wetland and deepwater habitat, as appropriate. Existing NWI maps and digital data for the study area were the primary base data for this characterization. (Note: This project was initiated prior to updating NWI data for this area; such data are now available, but were not ready in time to use for this assessment.) NYCDEP digital data for streams and NWI linear data were used to determine linkages among wetlands and between wetlands and deepwater habitats. Intermittent stream data were derived from U.S. Geological Survey topographic maps and their digital representations. No attempt was made to improve the geospatial or classification accuracy of the original data. Matching geospatial data from a variety of sources posed some challenges regarding alignment of a wetland to a stream. Where topographic information and stream location were not in proper alignment, a wetland in the correct topographic position (i.e., drainageway) was considered to be connected to the stream.
The existing NWI database contains geospatial information on both wetlands and deepwater habitats. Since this study's focus is on wetland assessment, wetlands had to be separated from deepwater habitats. Ponds were then separated from other wetlands, so that additional descriptors could be added.
Three main descriptors (landscape position, landform, and water flow path) were applied to each wetland by interpreting available map information, and in some cases, aerial photography was consulted. "Keys to Waterbody Type and Hydrogeomorphic-type Wetland Descriptors for U.S. Waters and Wetlands (Operational Draft)" (Tiner 2000) was initally used to classify these features. These data were updated using a slight revision of the keys "Dichotomous Keys and Mapping Codes for Wetland Landscape Position, Landform, Water Flow Path, and Waterbody Type Descriptors" (Tiner 2003a: Appendix A). Other modifiers were added to depict features such as headwater, drainage-divide, and human-impacted wetlands.
Landscape position defines the relationship between a wetland and an adjacent waterbody if present. For the study watersheds, three landscape positions were possible: 1) lotic (along rivers and streams and on their active floodplains), 2) lentic (along lakes and reservoirs), and 3) terrene (typically surrounded by upland, but including wetlands serving as sources of streams). Lotic wetlands were divided in lotic river and lotic stream wetlands by their width on a 1:24,000-scale map. Watercourses mapped as linear (single-line) features on NWI maps and on a U.S. Geological Survey topographic map (1:24,000) were designated as streams, whereas two-lined channels (polygonal features on the maps) were classified as rivers. Lotic wetlands were also subdivided into gradients for perennial waters: high (e.g., shallow mountain streams on steep slopes), middle (e.g., streams on moderate slopes), and low (e.g., mainstem rivers with considerable floodplain development or streams in flat sections in higher terrain), and intermittent gradient for waters not flowing year-round. All lotic wetlands are in contact with streams or rivers. Wetlands on floodplains surrounded by upland (nonhydric soil) were classified as terrene wetlands. Lentic wetlands were divided into two categories: natural and dammed, with the latter type separating wetlands associated with reservoirs from those along
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other controlled lakes, when possible.
Landform is the physical form or shape of a wetland. Six landform types were recognized in the study area: 1) basin, 2) flat, 3) slope, 4) floodplain, 5) island, and 6) fringe (Table 1). The floodplain landform was restricted to wetlands bordering perennial rivers and streams. Wetlands surrounded by nonhydric soils on floodplains were classified as floodplain wetlands (Terrene), except where the floodplain was cut off from river flow by roads, railroads, or levees. The basin (former floodplain) or flat (former floodplain) landform was assigned to the latter wetlands based on expected hydrology. Wetlands along intermittent streams were classified as either fringe, basin or flat depending on their predicted hydrology (i.e., semipermanently flooded to permanently flooded = fringe, seasonally flooded = basin; and temporarily flooded = flat).
Water flow path descriptors characterize the flow of water associated with wetlands. Seven patterns of flow were recognized for inland wetlands in the Delaware and Catskill watersheds: 1) throughflow, 2) throughflow-intermittent, 3) outflow, 4) outflow-intermittent, 5) inflow, 6) bidirectional flow, and 7) isolated. Throughflow wetlands have either a perennial watercourse (e.g. stream) or another type of wetland above and below it, so water passes through them (usually by way of a river or stream, but sometimes by ditches). The water flow path of lotic wetlands associated with perennial streams is throughflow. Throughflow-intermittent was applied to identify wetlands along intermittent streams. Where a streamside wetland has intermittent inflow and perennial outflow, the water flow path was classified as throughflow and the landscape position was labeled as lotic stream intermittent gradient. Lentic wetlands crossed by streams were designated as throughflow, while those located in embayments or coves with no stream inflow were classified as bidirectional flow since fluctuating lake or reservoir water levels appear to be the primary surface water source affecting their hydrology. Outflow wetlands have water leaving them all year-long, moving downstream via a watercourse (e.g., stream) or a slope wetland. If outflow is not constant (only occurs at certain times during the year), the flow pattern is classified as outflow-intermittent. Inflow wetlands are sinks where no outlet exists, yet water enters via an intermittent stream or seepage from an upslope wetland. Isolated wetlands are essentially closed depressions (geographically isolated) where water comes from surface water runoff and/or groundwater discharge. For this project, surface water connections are emphasized, since it is not possible to determine ground water linkages (especially outflow) without hydrologic investigations. Consequently, wetlands designated as isolated may have groundwater connections.
The headwater descriptor ("hw") was applied to wetlands along intermittent streams and first- and second-order perennial streams and to terrene wetlands that are the sources of these streams.
In the upper portions of watersheds, most streamside wetlands had organic soils (Carlisle or Palms muck). While these soils may occur in on floodplains, they are not alluvial soils formed in a depositional environment. Rather they are soils that have developed in place by the slow decomposition of plant matter. Wetlands in the intermittent stream reach were classified by map interpretation as lotic intermittent basin or flat wetlands (mostly the former), whereas the "floodplain" descriptor was applied to wetlands along perennial streams and rivers as they probably receive more water-carried sediments than the former, even where soils are organic.
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Care was taken to ensure that the lentic descriptor was not applied beyond the lake basin (upstream or downstream). Where a stream enters a lake through a lakeside wetland, the wetland was designated as lentic throughflow if it occurred within the lake basin. The upper limits of this wetland were determined by examining topography and the width of the stream valley. In most cases, where the stream valley narrowed, the wetland was classified as lotic, given that it is beyond significant lake influence. It should be recognized that the hydrology of some wetlands within the lake basin may be more influenced by groundwater discharge than by lake levels, but this could not be determined through map interpretation.
The pond modifer ("pd") was applied to any wetland in contact with a pond per request from NYCDEP. The pond may exert influence on the wetland vegetation or may simply have little or no influence on the wetland (e.g., where a pond represents only a small portion of the wetland such as bog eyelet pond or where an artificial pond was excavated from an existing wetland). Wetlands bordering ponds that were mapped by NWI as impounded ("h") should be significantly influenced by pond hydrology.
The floodplain modifier (“q”) was applied to any pond in a floodplain. These ponds should be located on alluvial soils. Since beaver ponds are created by stream blockage, there was no need to apply the "q" modifier to these ponds. These ponds typically convert the stream channel to a standing body of water. Wetlands associated with these types of ponds were typically classified as lotic stream wetlands with a "pd" modifier.
All NWI mapped wetlands in the both major watersheds were reviewed, reclassified by landscape position, landform, water flow path, and waterbody type (LLWW descriptors), and assigned an LLWW code. NYCDEP staff reviewed the preliminary classifications as well as performed field checks on numerous wetlands throughout these watersheds. Based on this review, many wetlands initially determined to be "isolated" wetlands were found to be connected to other wetlands via an intermittent stream or small perennial stream. Edits to the database were made based on NYCDEP comments. In general, if there was a wetland on both sides of a road, the wetlands were assumed to be connected; one was usually considered outflow (e.g., through a culvert), while the receiving wetland was typically classified as throughflow.
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Table 1. Definitions and examples of landform types (Tiner 2003a).
Landform Type General Definition Examples
Basin* a depressional (concave) landform lakefill bogs; wetlands in the including artificially created ones by saddle between two hills; impoundments, causeways, and roads wetlands in closed or open depressions, including narrow stream valleys; tidally
restricted estuarine wetlands
Slope a landform extending uphill (on a slope; seepage wetlands on typically crossing two or more contours hillside; wetlands along on a 1:24,000 map) drainageways or mountain streamsonslopes
Flat* a relatively level landform, often on wetlands on flat areas
broad level landscapes with high seasonal ground- water levels; wetlands on terraces along rivers/streams; wetlands on hillside benches; wetlands at toes of slopes
Floodplain a broad, generally flat landform wetlands on alluvium; occurring on a landscape shaped by bottomland swamps
fluvial or riverine processes
Fringe a landform occurring within the banks of buttonbush swamps; aquatic a nontidal waterbody (not on a floodplain) beds; semipermanently and often but not always subject to near flooded marshes; river and permanent inundation and a landform stream gravel/sand bars;
along an estuary subject to unrestricted salt and brackish marshes and
tidal flow or a regularly flooded landform flats; regularly flooded tidal
along a tidal freshwater river or stream fresh marsh or flat
Island a landform completely surrounded by deltaic and insular wetlands; water (including deltas) floating bog islands
*May be applied as sub-landforms within the Floodplain landform.
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General Scope and Limitations of Preliminary Functional Assessment
At the outset, it is important to emphasize that the functional assessment presented in this report is a preliminary evaluation based on wetland characteristics interpreted through remote sensing and using the best professional judgment of the senior author with input from NYCDEP personnel and others. Wetlands believed to be providing potentially significant levels of performance for a particular function were highlighted. As the focus of this report is on wetlands, the assessment of waterbodies (e.g., lakes, rivers, and streams) at providing the listed functions was not done, despite their rather obvious significant performance of functions like fish habitat and surface water detention. No attempt was made to produce a more qualitative ranking for each function or for each wetland based on multiple functions since this was beyond the scope of the current study. For a technical review of wetland functions, see Mitsch and Gosselink (2000) and for a broad overview, see Tiner (1998).
Functional assessment of wetlands can involve many parameters. Typically such assessments have been done in the field on a case-by-case basis, considering observed features relative to those required to perform certain functions or by actual measurement of performance and compared to reference standards. The present study does not seek to replace the need for such assessments as they are the ultimate assessment of the functions for individual wetlands. Yet, for a watershed analysis, basinwide field-based assessments are not practical nor cost-effective nor even possible given access considerations. For watershed planning purposes, a more generalized assessment is worthwhile for targeting wetlands that may provide certain functions, especially for those functions dependent on landscape position and vegetation lifeform. Subsequently, these results can be field-verified when it comes to actually evaluating particular wetlands for acquisition or other purposes. Current aerial photography may also be examined to aid in further evaluations (e.g., condition of wetland/stream buffers or adjacent land use) that can supplement the preliminary assessment.
This study employs a watershed assessment approach called "Watershed-based Preliminary Assessment of Wetland Functions" (W-PAWF). W-PAWF applies general knowledge about wetlands and their functions to develop a watershed overview that highlights possible wetlands of significance based on their predicted level of performance of various functions. To accomplish this objective, the relationships between wetlands and various functions must be simplified into a set of practical criteria or observable characteristics. Such assessments could also be further expanded to consider the condition of the associated waterbody and the neighboring upland or to evaluate the opportunity a wetland has to perform a particular function.
W-PAWF does not account for the opportunity that a wetland has to provide a function resulting from a certain land-use practice upstream or the presence of certain structures or land-uses
downstream. For example, two wetlands of equal size and like vegetation may be in the right landscape position to retain sediments. One, however, may be downstream of a land-clearing operation that has generated considerable suspended sediments in the water column, while the other is downstream from an undisturbed forest. The first wetland is most likely actively trapping sediment, while the second wetland is not or is not accumulating as much sediment. The W-PAWF is designed to reflect the potential for a wetland to provide a function. W-PAWF also does not consider the condition of the adjacent upland (e.g., level of outside disturbance) or
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the actual water quality of the associated waterbody which may be regarded as important metrics for assessing the “health” of individual wetlands (not part of this study). Collection and analysis of these data were beyond the scope of the study.
This preliminary assessment does not obviate the need for more detailed assessments of the various functions. It should be viewed as a starting point for more rigorous assessments, as it attempts to cull out wetlands that may likely produce significant levels of performance for certain functions based on generally accepted principles and the source information used for this analysis. This type of assessment is most useful for regional or watershed planning purposes.
It is also important to recognize limitations derived from source data. These limitations include conservative interpretations of forested wetlands (especially evergreen types) and drier-end wetlands (e.g., wet meadows, especially those used as pastures; see Tiner 1997b for additional information), and the omission of small or narrow wetlands. Despite these limitations, the NWI dataset represents the most extensive and current database on the distribution, extent, and type of wetlands in the New York City Water Supply System. NWI data for this study were based on 1982-1987, 1:58,000 color infrared aerial photography. These data were being updated while this study was in progress and unfortunately were not available for this assessment. NYCDEP personnel found that a few of the mapped wetlands were no longer present in 2002-3 and these wetlands were removed from the database. They also noted a few classification errors that were also corrected. The U.S. Geological Survey's digital raster graphics (DRGs) were used to determine whether small isolated wetlands were within a forest matrix. This land cover data may not reflect current conditions, so more of these wetlands may have been designated as having high potential for other wildlife habitat than if current aerial photography was analyzed.
For the functional assessment, the wetlands in the drainage basin contributing to the reservoir were emphasized. Wetlands within the reservoir, such as marshes and exposed flats (i.e., unconsolidated shores) were not included in the assessment since they are not part of the contributing watershed, but are actually part of the reservoir itself.
Rationale for Preliminary Functional Assessment
Eight functions were evaluated: 1) surface water detention, 2) streamflow maintenance, 3) nutrient transformation, 4) sediment retention, 5) shoreline stabilization, 6) provision of fish habitat, 7) provision of waterfowl and waterbird habitat, and 8) provision of other wildlife habitat. The criteria used for identifying wetlands of significance for these functions were taken from Tiner (2003b) which is included as Appendix B. A list of the wetland types designated as significant for each function is presented in Table 2. This list includes only freshwater wetland types found in the Delaware and Catskill watersheds.
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Table 2. List of wetlands of potential significance for eight funtions for use in the Delaware and Catskill watersheds. (Source: Adapted from Tiner 2003b).
Function/Potential
Significance Wetland Types
Surface Water Detention
High Lentic Basin, Lentic Fringe, Lentic Island (basin and fringe), Lentic Flat associated with reservoirs and flood control dams, Lotic Basin, Lotic Floodplain, Lotic Fringe, Lotic Island associated with Floodplain area, Lotic Island basin, Ponds Throughflow (in-stream) and associated Fringe and Basin wetlands, Ponds Bidirectional and associated wetlands
Moderate Lotic Flat, Lotic Island flat, Lentic Flat, Other Terrene Basins, Other Ponds and associated wetlands (excluding sewage treatment ponds and similar waters)
Streamflow Maintenance
High Nonditched Headwater Wetlands (Terrene, Lotic, and Lentic), Headwater Ponds
and Lakes (classified as PUB...on NWI) (Note: Lotic Stream Basin or Floodplain basin Wetlands along 2nd order streams should also be rated high; possibly expand to 3rd order streams in hilly or mountainous terrain.)
Moderate Ditched Headwater Wetlands (Terrene, Lotic, and Lentic), Lotic (Nontidal) Floodplain, Throughflow Ponds and Lakes (classified as PUB on NWI) and their associated wetlands, Terrene Outflow wetlands (associated with streams not major rivers), Outflow Ponds and Lakes (classified as PUB... on NWI)
Special Note: All these wetlands should also be considered important for fish and shellfish as they are vital to sustaining streamflow necessary for the survival of these aquatic organisms.
Nutrient Transformation
High Vegetated wetlands (and mixes with nonvegetated wetlands or unconsolidated bottom; even where nonvegetated predominates) with seasonally flooded (C), seasonally flooded/saturated (E), semipermanently flooded (F), and permanently flooded (H) water regimes, vegetated wetlands with permanently saturated water regime (B)
Moderate Vegetated wetlands with temporarily flooded (A) water regime
Retention of Sediments
and Other Particulates
High Lentic Basin, Lentic Fringe (vegetated only), Lentic Island (vegetated) Lotic Basin, Lotic Floodplain, Lotic Fringe (vegetated), Lotic Island (vegetated), Throughflow Ponds and Lakes (in-stream; designated as PUB... on NWI) and associated vegetated wetlands, Bidirectional Ponds and associated vegetated wetlands
Moderate Lotic Island (nonvegetated), Lotic Flat (excluding bogs), Lentic Flat, Other Terrene Basins excluding bogs), Terrene wetlands associated with ponds (excluding excavated ponds; also excluding bogs and slope wetlands), Other Ponds and Lakes (classified as PUB... on NWI) and associated wetlands (excluding bogs and slope wetlands)
Note: Ponds with minimal watersheds - possibly gravel pit ponds, impoundments completely surrounded by dikes, and dug-out ponds with little surface water inflow should be excluded.
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Table 3 (continued).
Function/Potential
Significance Wetland Types
Shoreline Stabilization
High Lotic wetlands (vegetated except island and isolated types), Lentic wetlands (vegetated except island types)
Moderate Terrene vegetated wetlands associated with ponds (e.g., Fringe-pond, Flat-pond, and Basin-pond)
Provision of Fish Habitat
High Lacustrine Semipermanently Flooded (excluding wetlands along intermittent streams), Lacustrine Littoral Aquatic Bed, Lacustrine Littoral Unconsolidated Bottom/Vegetated Wetland, Lacustrine Littoral Vegetated Wetland with a Permanently Flooded water regime, Palustrine Semipermanently Flooded (excluding wetlands along intermittent streams; must be contiguous with a permanent waterbody such as PUBH, L1UBH, or R2/R3UBH), Palustrine Aquatic Bed, Palustrine Unconsolidated Bottom/Vegetated Wetland, Palustrine Vegetated Wetland with a Permanently Flooded water regime, Ponds (PUBH.. on NWI; not PUBF) associated with Semipermanently Flooded Vegetated Wetland
Moderate Lentic wetlands that are PEM1E, Lotic River or Stream wetlands that are PEM1E (including mixtures with Scrub-Shrub or Forested wetlands), Semipermanently flooded Phragmites wetlands (PEM5F) where contiguous with a permanent waterbody, Other Ponds and associated Fringe wetlands (i.e., Terrene Fringe-pond) (excluding industrial, stormwater treatment/detention, similar ponds in highly disturbed landscapes, and ponds with K and F water regimes)
Important for
Stream Shading Lotic Stream wetlands that are Palustrine Forested or Scrub-shrub wetlands (includes mixes where one of these types predominates; excluding those along intermittent streams; also excluding shrub bogs) (Note that although forested wetlands are designated as important for stream shading, forested upland provide similar functions)
Note: Many of these habitats are also important for wetland-dependent amphibians, reptiles, and aquatic invertebrates.
Provision of Waterfowl
and Waterbird Habitat
High Lacustrine Semipermanently Flooded, Lacustrine Littoral Aquatic Bed, Lacustrine
Littoral Vegetated wetlands with an H water regime, Lacustrine Unconsolidated Shores (F, E, or C water regimes; mudflats), Palustrine Semipermanently Flooded (excluding Phragmites stands, but including mixtures containing this species - EM5), Palustrine Aquatic Bed, Palustrine Vegetated wetlands with a H water regime, Palustrine Unconsolidated Shores (F, E, or C water regimes; mudflats), Seasonally Flooded/Saturated Palustrine wetlands impounded or beaver-influenced (all vegetation types [except PEM5Eh and PEM5Eb] and associated PUB waters), Lotic River or Stream wetlands that are PEM1E (including mixtures with Scrub-Shrub or Forested wetlands), Ponds associated with Semipermanently Flooded Vegetated wetlands, Ponds associated with all of the wetland types listed as high for this function
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Table 3 (continued).
Function/Potential
Significance Wetland Types
Provison of Waterfowl
and Waterbird Habitat
Moderate Phragmites wetlands that are Seasonally Flooded/Saturated and wetter (PEM5E; PEM5F; PEM5H) and contiguous with a waterbody, Other Lacustrine Littoral Unconsolidated Bottom, Other Palustrine Unconsolidated Bottom (excluding industrial, commercial, stormwater detention, wastewater treatment, and similar ponds), Palustrine Emergent wetlands (including mixtures with Scrub-shrub) that are Seasonally Flooded and associated with permanently flooded waterbodies
Significant for
Wood Duck Lotic wetlands (excluding those along intermittent streams) that are Forested or Scrub-shrub or mixtures of these types with C, E, F, or H water regime; Lotic wetlands that are mixed Forested/Emergent or Unconsolidated Bottom/Forested with a E, F, or H water regime
Provision of Other
Wildlife Habitat
High Large vegetated wetlands (>20 acres, excluding open water and nonvegetated areas), small diverse wetlands (10-20 acres with 2 or more covertypes; excluding EM5 or open water as one of the covertypes), small, seasonally flooded or wetter, isolated wetlands in a cluster of two or more (within 1000-feet of one another; including small ponds that may be vernal pools) occurring within an upland forest matrix
Moderate Other vegetated wetlands
Note: Although in general, ponds are not listed here as important as significant for other wildlife, it should be recognized that species of frogs, turtles, and some other wildlife depend on these habitats; by and large, these wetlands have already been designated as important for fish and waterbirds, so they are not listed here.
Note: Nonvegetated lacustrine wetlands and semipermanently flooded vegetated wetlands (typically emergent types) located within each NYC reservoir were considered part of the reservoir proper. Since the assessment focused on wetlands in the watershed area draining into each NYC reservoir, the assessment of within-reservoir wetlands is not reported. However, the database created for this project contains information on the predicted functions of these wetlands for use by NYCDEP.
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GIS Analysis and Data Compilation
The geographic information system (GIS) used for this project was ArcInfo. Several GIS analyses were performed to produce wetland statistics (acreage summaries), a preliminary assessment of wetland functions, and maps for each reservoir basin. Tables summarizing the results of the inventory were prepared to show extent of different wetland types by NWI classifications and by LLWW descriptors. NWI and LLWW wetland acreage totals differ because palustrine open water wetlands (NWI) were treated as ponds and, in some cases, as lakes according to LLWW. For individual reservoir basins, wetlands in the reservoir were culled from the wetlands in the surrounding drainage area. This was done because NYCDEP manages the reservoirs and was more concerned about the condition and function of wetlands in the surrounding watershed than of wetlands that are part of the reservoir waterbody. Wetlands designated as within the reservoir were mostly unconsolidated shores (i.e., exposed bottoms during reservoir drawdown). Some vegetated wetlands were also included within the reservoir if they were in standing water for all of the year (i.e., semipermanently flooded or permanently flooded types). Within-reservoir wetlands are reported in the acreage summaries but were not included in the functional assessment totals since the evaluation was intended to focus on wetlands in the contributing drainage area for the reservoir; their predicted functions are recorded in the database. Eight functions were evaluated using the database: 1) surface water detention, 2) streamflow maintenance, 3) nutrient transformation, 4) sediment retention, 5) shoreline stabilization, 6) provision of fish habitat, 7) provision of waterfowl and waterbird habitat, and 8) provision of other wildlife habitat.
Maps
A series of 13 maps was produced for each reservoir basin within the Delaware and Catskill watersheds. Six reservoir basins were evaluated: Cannonsville, Pepacton, Neversink, Rondout, Schoharie, and Ashokan. Cannonsville maps were divided into two sections: Southwest (A-series) and Northeast (B-series) due to the size of this reservoir basin. All maps were produced at a scale of 1:40,000 for this report.
For each reservoir basin, the first five maps depict the results of the wetlands inventory: wetlands by NWI types and by landscape position, landform, combined landscape-landform, and water flow path. Each of the remaining maps (Maps 6 through 13) highlights wetlands in the reservoir's catchment area that may perform each of the eight selected functions at a significant level. A list of the 13 maps follows: Map 1 - Wetlands and Deepwater Habitats Classified by NWI Types, Map 2 - Wetlands Classified by Landscape Position, Map 3 - Wetlands Classified by Landform, Map 4 - Wetlands Classified by Landscape Position and Landform, Map 5 - Wetlands Classified by Water Flow Path, Map 6 – Potential Wetlands of Significance for Surface Water Detention, Map 7 - Potential Wetlands of Significance for Streamflow Maintenance, Map 8 - Potential Wetlands of Significance for Nutrient Transformation, Map 9 - Potential Wetlands of Significance for Sediment Retention, Map 10 - Potential Wetlands of Significance for Shoreline Stabilization, Map 11 - Potential Wetlands of Significance for Provision of Fish Habitat, Map 12 - Potential Wetlands of Significance for Provision of Waterfowl/Waterbird Habitat, and Map 13 - Potential Wetlands of Significance for Provision of Other Wildlife Habitat.
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Results
The results are presented for the seven reservoir basins representing the study area. Data are organized by major watershed, first for the Delaware and then for the Catskill. A reservoir basin profile summarizes pertinent data for each reservoir basin. It consists of a summary of wetland types both in and out of the reservoir (wetland characterization) and a preliminary assessment of functions for wetlands in the watershed area above the reservoir (the catchment area). For the functional assessment, wetlands in the catchment area were emphasized. Wetlands within the reservoir, such as marshes and exposed flats (i.e., unconsolidated shores) were not included in the assessment totals since they are not part of the contributing watershed, but are actually part of the reservoir itself. Maps are presented in a separate folder contained on the compact disk (CD) version of the report and are hyperlinked to the report; they are not included in the hardcopy version of this report. One set of hardcopy maps were printed and given to NYCDEP.
DELAWARE WATERSHED
Four reservoir basins are contained within the Delaware watershed: Cannonsville, Pepacton, Neversink, and Rondout.
Cannonsville Reservoir Basin Profile
Wetland Characterization
Wetlands by NWI Types
According to the NWI, the Cannonsville Reservoir Basin had over 2,800 acres of wetlands (including ponds), while the reservoir itself had over 3,000 acres of exposed bottoms (unconsolidated shore) at the time of the survey (Table 3; Maps 1A & 1B). Emergent wetlands (including emergent/scrub-shrub mixed communities) were the predominant palustrine type with over 1,000 acres inventoried, accounting for 40% of the wetlands in the contributing watershed area. Nonvegetated wetlands (ponds) were next in abundance with nearly 800 acres, representing 28% of the wetlands. Scrub-shrub and forested wetlands comprised 17% and 14% of the wetlands, respectively. Deepwater habitats (e.g., lakes and reservoirs) totaled nearly 2,300 acres (1,853.6 acres of lacustrine including 1,701.7 acres in the reservoir at the time of the inventory, and 435.1 acres of riverine habitat).
Wetlands by LLWW Types
A total of 816 wetlands were identified, excluding ponds (Table 4). The wetland acreage based on LLWW classification was 2,007.9 acres. Most (79%) of the wetland acreage was lotic wetland (Maps 2A & 2B; 68% lotic stream and 11% lotic river). The remainder was mostly terrene wetland (18%). Only 3% of the wetland acreage was lentic.
From the landform perspective, floodplain and basin wetlands were most extensive, accounting for 61% and 23% of the wetland acreage, respectively (Maps 3A & 3B). Flat wetlands accounted for 9% and fringe wetlands 5%. Nearly 2% of the wetland acreage was represented
12
by slope wetlands and less than 1% was the island type. Maps 4A & 4B show the distribution of wetlands by a combination of landscape position and landform. Considering water flow path, 81% of the wetland acreage was throughflow-(68% perennial and 13% intermittent) (Maps 5A & 5B). Outflow types accounted for 11% of the acreage (7% intermittent and 4% perennial). Isolated acreage amounted to 7% of the total. About 1% of the wetland acreage was subjected to bidirectional flow.
For the 1,081 ponds identified (677.9 acres), 45% of the acreage was throughflow (34% perennial and 11% intermittent), 34% isolated, 21% outflow (13% intermittent and 8% perennial), and about 1% inflow.
13
Table 3. Wetlands classified by NWI types for the Cannonsville Reservoir Basin.
NWI Wetland Type Acreage Acreage
(within reservoir) (outside reservoir)
Lacustrine Wetlands 3,039.5 0.0
Palustrine Wetlands
Emergent - 1,019.3
Emergent/Scrub-Shrub - 90.9
(subtotal Emergent) (0.0) (1,110.2)
Forested, Broad-leaved Deciduous - 272.4
Forested, Mixed - 19.4
Forested, Needle-leaved Evergreen - 70.1
Forested, Dead - 20.1
Forested/Scrub-Shrub - 15.6
(subtotal Forested) (0.0) (397.6)
Scrub-Shrub, Deciduous - 390.2
Scrub-Shrub, Evergreen 0.8
Scrub-Shrub, Mixed - 2.3
Scrub-Shrub/Emergent - 53.3
Scrub-Shrub/Forested - 24.1
(subtotal Scrub-Shrub) (0.0) (470.7)
Unconsolidated Bottom - 793.6
--------------------------------------------- -------------- ------------
Palustrine Subtotal 0.0 2,772.1
Riverine Wetlands 0.0 35.8
GRAND TOTAL (ALL WETLANDS) 3,039.5 2,807.9
14
Table 4. Wetlands in the Cannonsville Reservoir Basin classified by LLWW types.
Landscape Number
Position Landform Water Flow of Wetlands Acreage
Lentic (LE)
Basin (BA) Bidirectional (BI) 8 17.1
Throughflow (TH) 7 16.6
Throughflow-
Intermittent (TI) 1 2.5
(subtotal) (16) (36.8)
Flat (FL) Bidirectional (BI) 1 1.4
Throughflow (TH) 2 7.0
(subtotal) (3) (8.4)
Fringe (FR) Bidirectional (BI) 1 1.4
Throughflow (TH) 2 3.6
(subtotal) (3) (5.1)
Island (IL) Bidirectional (BI) 1 1.0
(Subtotal Lentic) (23) (51.3)
Lotic River
(LR)
Floodplain (FP) Throughflow (TH) 71 190.6
Fringe (FR) Throughflow (TH) 13 16.4
Island (IL) Throughflow (TH) 5 10.2
(Subtotal Lotic River) (89) (217.2)
Lotic Stream
(LS)
Basin (BA) Throughflow (TH) 12 42.1
Throughflow-
Intermittent (TI) 53 129.2
(subtotal) (65) (171.3)
Flat (FL) Throughflow (TH) 10 22.9
Throughflow-
Intermittent (TI) 34 94.4
(subtotal) (44) (117.3)
Floodplain (FP) Throughflow (TH) 304 1,020.0
Throughflow-
Intermittent (TI) 2 3.3
(subtotal) (306) (1,023.2)
Fringe (FR) Throughflow (TH) 31 47.1
Throughflow-
Intermittent (TI) 3 9.0
(subtotal) (34) (56.1)
Slope (SL) Throughflow (TH) 1 0.5
(Subtotal Lotic Stream) (450) (1,368.5)
15
Terrene (TE)
Basin (BA) Inflow (IN) 1 0.6
Isolated (IS) 97 92.3
Outflow (OU) 20 62.5
Outflow Intermitttent (OI) 42 83.5
Throughflow
Intermittent (TI) 2 16.3
(subtotal) (162) (255.2)
Flat (FL) Isolated (IS) 31 24.0
Outflow Intermittent (OI) 14 20.7
Outflow (OU) 5 11.8
(subtotal) (50) (56.5)
Floodplain (FP) Isolated (IS) 3 2.1
Outflow Intermittent (OI) 5 8.8
(subtotal) (8) (10.8)
Fringe (FR) Isolated (IS) 4 7.3
Outflow Intermittent (OI) 1 1.3
Outflow (OU) 4 7.9
(subtotal) (9) (16.5)
Slope (SL) Isolated (IS) 10 13.4
Outflow Intermittent (OI) 11 15.0
Outflow (OU) 4 3.5
(subtotal) (25) (31.9)
(Subtotal Terrene) (254) (370.9)
TOTAL LLWWTypes* 816 2,007.9
*Does not include 1,081 ponds that totaled 677.9 acres.
Note: Subtotals may be slightly different than the sum of acreages shown due to computer round-off procedures.
16
Preliminary Assessment of Wetland Functions
The results for each wetland function for the Cannonsville Reservoir Basin are given in Table 5. Refer to the maps for locations of these wetlands; maps are hotlinked to the table.
Ninety-three percent of the wetland acreage was predicted to be significant for surface water detention. Two functions were projected to be performed at significant levels by more than 80% of the wetland acreage: sediment retention (87%) and streamflow maintenance (84%). Other functions performed at significant levels by more than 60% of the wetland acreage were nutrient transformation (70%), provision of other wildlife habitat (68%), and shoreline stabilization (60%). Cannonsville wetlands contributed less to waterfowl and waterbird habitat and fish habitat, but over 35% of the wetland acreage was predicted to perform these functions at significant levels. For the latter, if focused solely on fish nursery and spawning grounds, only 36% of the wetlands might serve this function, with another 13% of the acreage being important for maintaining stream temperatures (i.e., stream shading by trees and shrubs). Wetlands important for streamflow maintenance (84% of the wetland acreage) are also vital to providing aquatic habitat for fish.
17
Table 5. Predicted wetland functions for the Cannonsville Reservoir Basin (excluding wetlands within the reservoir). Click on maps to view potential wetlands of significance for each function.
Predicted
Function Level Acreage Percent of Wetlands
Surface Water Detention High 1,513.2 54
(Maps 6A & 6B) Moderate 1,081.1 39
Streamflow Maintenance High 1,923.5 69
(Maps 7A & 7B) Moderate 435.1 15
Nutrient Transformation High 1,236.1 44
(Maps 8A & 8B) Moderate 741.5 26
Sediment Retention High 1,492.7 53
(Maps 9A & 9B) Moderate 951.7 34
Shoreline Stabilization High 1,591.4 57
(Maps 10A & 10B) Moderate 83.7 3
Fish Habitat High 34.3 1
(Maps 11A & 11B) Moderate 988.8 35
Shading 361.2 13
Waterfowl and Waterbird
Habitat High 439.1 16
(Maps 12A & 12B) Moderate 638.9 23
Wood Duck 3.6 <1
Other Wildlife Habitat High 502.7 18
(Maps 13A & 13B) Moderate 1,407.1 50
18
Pepacton Reservoir Basin Profile
Wetland Characterization
Wetlands by NWI Types
According to the NWI, the Pepacton Reservoir Basin had over 1,550 acres of wetlands, with only 5.8 acres in the reservoir itself (Table 6; Map 1). Emergent wetlands and ponds were the predominant palustrine types, totaling more than 1,000 acres and accounting for 69% of the wetlands. The former type was slightly more abundant, representing 36% of the wetlands, whereas ponds accounted for 33%. Scrub-shrub wetlands and forested wetlands comprised 20% and 9% of the wetlands, respectively. Deepwater habitats (e.g., lakes and reservoirs) totaled over 5,700 acres (5,657.7 acres of lacustrine including 5,596.4 acres in the reservoir, and 52.3 acres of riverine habitat).
Wetlands by LLWW Types
A total of 445 wetlands were identified, excluding ponds (Table 7). The wetland acreage based on LLWW classification was 1,034.9 acres. Most (80%) of the wetland acreage was lotic wetland (Map 2; 75% lotic stream and 5% lotic river). The remainder was mostly terrene wetland (14%). Only 6% of the wetland acreage was lentic.
From the landform perspective, floodplain wetlands were most extensive, accounting for 67% of the wetland acreage (Map 3). Basin wetlands were next ranked in acreage, representing 19% of the total acreage. Fringe wetlands and flat wetlands accounted for 7% and 5%, respectively. Slope wetlands comprised nearly 3% of the acreage. Map 4 shows the distribution of wetlands by a combination of landscape position and landform. Considering water flow path, 84% of the wetland acreage was throughflow (81% perennial and 3% intermittent).(Map 5). Outflow wetlands totaled 7% of the acreage (4% intermittent and 3% perennial). Isolated types made up about 7% and bidirectional flow almost 2% of the acreage, respectively. Inflow wetlands represented less than 1% of the acreage.
For the 798 ponds identified (424.2 acres), 54% of the acreage was throughflow (47% perennial and 7% intermittent), 33% isolated, 13% outflow (9% perennial and 4% intermittent), and the remaining <1% mostly inflow.
19
Table 6. Wetlands classified by NWI types for the Pepacton Reservoir Basin.
NWI Wetland Type Acreage Acreage
(within reservoir) (outside reservoir)
Lacustrine Wetlands 2.4 0.0
Palustrine Wetlands
Aquatic Bed - 0.1
Emergent 3.5 448.5
Emergent/Forested - 11.6
Emergent/Scrub-Shrub - 97.7
Emergent/Unconsolidated Bottom - 4.5
(subtotal Emergent) (3.5) (562.3)
Forested, Broad-leaved Deciduous - 82.5
Forested, Needle-leaved Evergreen - 49.8
Forested, Dead - 6.1
Forested/Scrub-Shrub - 5.9
(subtotal Forested) (0.0) (144.3)
Scrub-Shrub, Deciduous - 235.6
Scrub-Shrub, Evergreen - 0.6
Scrub-Shrub/Emergent - 62.2
Scrub-Shrub/Forested - 5.3
(subtotal Scrub-Shrub) (0.0) (303.7)
Unconsolidated Bottom - 513.1
Unconsolidated Shore - 0.1
(subtotal nonvegetated) (0.0) (513.2)
--------------------------------------------- -------------- ------------
Palustrine Subtotal 0.0 1,523.6
Riverine Wetlands - 31.1
GRAND TOTAL (ALL WETLANDS) 5.9 1,554.7
20
Table 7. Wetlands in the Pepacton Reservoir Basin classified by LLWW types.
Landscape Number
Position Landform Water Flow of Wetlands Acreage
Lentic (LE)
Basin (BA) Bidirectional (BI) 12 13.1
Throughflow (TH) 8 27.1
(subtotal) (20) (40.3)
Flat (FL) Bidirectional (BI) 3 2.4
Throughflow (TH) 4 16.7
(subtotal) (7) (19.1)
Island (IL) Bidirectional (BI) 1 0.8
(Subtotal Lentic) (28) (60.2)
Lotic River
(LR)
Floodplain (FP) Throughflow (TH) 12 41.8
Fringe (FR) Throughflow (TH) 8 12.8
(Subtotal Lotic River) (20) (54.6)
Lotic Stream
(LS)
Basin (BA) Throughflow (TH) 11 39.4
Throughflow-
Intermittent (TI) 15 18.8
(subtotal) (26) (58.3)
Flat (FL) Throughflow (TH) 4 5.3
Throughflow-
Intermittent (TI) 11 11.4
(subtotal) (15) (16.6)
Floodplain (FP) Throughflow (TH) 213 645.6
Fringe (FR) Throughflow (TH) 42 46.7
Slope (SL) Throughflow (TH) 5 4.2
(Subtotal Lotic Stream) (301) (771.4)
Terrene (TE)
Basin (BA) Inflow (IN) 1 3.7
Isolated (IS) 36 52.9
Outflow (OU) 8 13.6
Outflow Intermittent (OI) 16 28.4
(subtotal) (61) (98.7)
Flat (FL) Inflow (IN) 1 0.4
Isolated (IS) 10 9.6
Outflow (OU) 2 3.6
Outflow Intermittent (OI) 3 3.2
(subtotal) (16) (16.7)
Floodplain (FP) Isolated (IS) 2 1.5
Fringe (FR) Isolated (IS) 1 3.9
21
Outflow (OU) 1 4.2
Outflow Intermittent (OI) 1 0.4
(subtotal) (3) (8.6)
Slope (SL) Isolated (IS) 2 1.2
Outflow (OU) 4 11.1
Outflow Intermittent (OI) 8 11.0
(subtotal) (14) (23.3)
(Subtotal Terrene) (96) (148.7)
TOTAL LLWWTypes* 445 1,034.9
*Does not include 798 ponds that totaled 424.2 acres.
Note: Subtotals may be slightly different than the sum of acreages shown due to computer round-off procedures.
22
Preliminary Assessment of Wetland Functions
The results for each wetland function for the Pepacton Reservoir Basin are given in Table 8. Refer to the maps for locations of these wetlands; maps are hotlinked to the table.
Two functions were predicted to be performed by more than 80% of the wetland acreage in this basin: surface water detention (89%) and sediment retention (86%). Functions performed by more than 50% of the wetland acreage were nutrient transformation (65%), provision of other wildlife habitat (64%), streamflow maintenance (58%), and shoreline stabilization (57%). Provision of habitat for waterfowl and waterbirds and for fish were predicted to be performed at significant levels by more than 40% of the wetland acreage. An additional 18% of the acreage was deemed potentially significant for shading streams, important to moderating stream temperatures for aquatic life.
23
Table 8. Predicted wetland functions for the Pepacton Reservoir Basin (excluding wetlands within the reservoir). Click on maps to view potential wetlands of significance for each function.
Predicted
Function Level Acreage Percent of Wetlands
Surface Water Detention High 844.6 54
(Map 6) Moderate 551.4 35
Streamflow Maintenance High 632.0 41
(Map 7) Moderate 260.3 17
Nutrient Transformation High 706.7 45
(Map 8) Moderate 303.5 20
Sediment Retention High 820.0 53
(Map 9) Moderate 516.8 33
Shoreline Stabilization High 858.8 55
(Map 10) Moderate 33.7 2
Fish Habitat High 27.5 2
(Map 11) Moderate 636.1 41
Shading 274.8 18
Waterfowl and Waterbird
Habitat (Map 12) High 329.3 21
Moderate 383.6 25
Other Wildlife Habitat High 221.8 14
(Map 13) Moderate 780.0 50
24
Neversink Reservoir Basin Profile
Wetland Characterization
Wetlands by NWI Types
According to the NWI, the Neversink Reservoir Basin had over 500 acres of wetlands including 25 acres in the reservoir (Table 9; Map 1). Forested wetlands were the predominant palustrine type with nearly 177 acres, accounting for 37% of the wetlands in the contributing watershed area. Nonvegetated wetlands (ponds and riverbanks) accounted for 35% of the wetlands. Scrub-shrub wetlands and emergent wetlands comprised 18% and 9% of the wetlands, respectively. Deepwater habitats (e.g., lakes and reservoirs) totaled about 1,500 acres (1,471.2 acres of lacustrine in the reservoir, and 29.5 acres of riverine habitat).
Wetlands by LLWW Types
A total of 157 wetlands were identified, excluding ponds (Table 10). The wetland acreage based on LLWW classification was 380.6 acres. Most (78%) of the wetland acreage was lotic wetland (Map 2; 52% lotic river and 26% lotic stream). The remainder was mostly terrene wetland (20%). Only 2% of the wetland acreage was lentic.
From the landform perspective, floodplain and basin wetlands were most extensive, accounting for 42% and 34% of the wetland acreage, respectively (Map 3). Fringe wetlands accounted for 20% and flat wetlands 3%. Map 4 shows the distribution of wetlands by a combination of landscape position and landform. Considering water flow path, 79% of the wetland acreage was throughflow-(63% perennial and 16% intermittent) (Map 5). Outflow wetlands made up 15% of the acreage (12% intermittent and 3% perennial). Isolated types accounted for 6% of the acreage. Bidirectional flow made up less than 1% of the wetland acreage.
For the 85 ponds identified (62.2 acres), 70% of the acreage was throughflow (17% perennial and 53% intermittent), 21% outflow (4% perennial and 17% intermittent), and 9% isolated.
25
Table 9. Wetlands classified by NWI types for the Neversink Reservoir Basin.
NWI Wetland Type Acreage Acreage
(within reservoir) (outside reservoir)
Palustrine Wetlands
Emergent 13.8 44.8
Forested, Broad-leaved Deciduous - 69.9
Forested, Mixed - 19.7
Forested, Needle-leaved Evergreen - 81.7
Forested, Dead - 5.4
(subtotal Forested) (0.0) (176.7)
Scrub-Shrub, Deciduous - 80.9
Scrub-Shrub, Evergreen - 1.2
Scrub-Shrub, Mixed - 1.5
Scrub-Shrub/Emergent - 4.4
(subtotal Scrub-Shrub) (0.0) (88.0)
Unconsolidated Bottom 11.6 96.9
--------------------------------------------- -------------- ------------
Palustrine Subtotal 25.4 406.4
Riverine Wetland 0.0 71.0
GRAND TOTAL (ALL WETLANDS) 25.4 477.4
26
Table 10. Wetlands in the Neversink Reservoir Basin classified by LLWW types.
Landscape Number
Position Landform Water Flow of Wetlands Acreage
Lentic (LE) Basin (BA) Bidirectional (BI) 4 2.5
Throughflow (TH) 2 2.3
(subtotal) (6) (4.8)
Island (IL) Bidirectional (BI) 1 0.4
(Subtotal Lentic) (7) (5.2)
Lotic River
(LR) Floodplain (FP) Throughflow (TH) 37 127.2
Fringe (FR) Throughflow (TH) 42 70.8
Island (IL) Throughflow (TH) 1 0.2
(Subtotal Lotic River) (80) (198.2)
Lotic Stream
(LS) Basin (BA) Throughflow (TH) 1 6.4
Throughflow-
Intermittent (TI) 21 50.3
(subtotal) (22) (56.7)
Flat (FL) Throughflow-
Intermittent (TI) 4 3.5
Floodplain (FP) Throughflow (TH) 12 34.0
Fringe (FR) Throughflow-
Intermittent (TI) 3 5.7
(Subtotal Lotic Stream) (41) (99.9)
Terrene (TE) Basin (BA) Isolated (IS) 7 18.8
Outflow (OU) 2 8.5
Outflow Intermittent (OI) 9 39.4
(subtotal) (18) (66.7)
Flat (FL) Isolated (IS) 1 1.1
Outflow (OU) 1 1.0
Outflow Intermittent (OI) 4 5.4
(subtotal) (6) (7.4)
Slope (SL) Isolated (IS) 2 1.1
Outflow (OU) 2 1.6
Outflow Intermittent (OI) 1 0.5
(subtotal) (5) (3.2)
(Subtotal Terrene) (29) (77.3)
TOTAL LLWWTypes* 157 380.6
*Does not include 85 ponds that totaled 62.2 acres.
Note: Subtotals may be slightly different than the sum of acreages shown due to computer round-off procedures.
27
Preliminary Assessment of Wetland Functions
The results for each wetland function for the Neversink Reservoir Basin are given in Table 11. Refer to the maps for locations of these wetlands; maps are hotlinked to the table.
Ninety percent of the wetland acreage in this basin was predicted to be significant for surface water detention. Functions projected to be performed at significant levels by more than 50% of the wetland acreage were sediment retention (74%), streamflow maintenance (73%), nutrient transformation (65%), provision of other wildlife habitat (65%) and shoreline stabilization (50%). The remaining functions -- provision of fish habitat and provision of waterfowl and waterbird habitat -- were expected to be performed at significant levels by 20-23% of the wetland acreage, respectively.
28
Table 11. Predicted wetland functions for the Neversink Reservoir Basin (excluding wetlands within the reservoir). Click on maps to view potential wetlands of significance for each function.
Predicted
Function Level Acreage Percent of Wetlands
Surface Water Detention High 296.1 62
(Map 6) Moderate 132.4 28
Streamflow Maintenance High 211.0 44
(Map 7) Moderate 136.2 29
Nutrient Transformation High 181.2 38
(Map 8) Moderate 128.4 27
Sediment Retention High 228.7 48
(Map 9) Moderate 125.5 26
Shoreline Stabilization High 231.9 49
(Map 10) Moderate 4.2 1
Fish Habitat High 0 -
(Map 11) Moderate 96.8 20
Shading 17.8 4
Waterfowl and Waterbird
Habitat (Map 12) High 49.7 10
Moderate 59.8 13
Wood Duck 1.2 <1
Other Wildlife Habitat High 105.8 22
(Map 13) Moderate 203.7 43
29
Rondout Reservoir Basin Profile
Wetland Characterization
Wetlands by NWI Types
According to the NWI, the Rondout Reservoir Basin had nearly 385 acres of wetlands including 3 acres within the reservoir (Table 12; Map 1). Forested wetlands, the predominant palustrine type with almost 212 acres, accounted for 55% of the wetlands. Nearly 78 acres of emergent wetlands were inventoried; they comprised 20% of the wetlands. Nonvegetated wetlands (ponds and exposed shores of rivers and lakes) accounted for 17% of the wetlands, while scrub-shrub wetlands made up 7%. Deepwater habitats (e.g., lakes and reservoirs) totaled about 2,080 acres (2,078.9 acres of lacustrine including 2,028.8 acres in the reservoir, and 1.3 acres of riverine habitat).
Wetlands by LLWW Types
A total of 81 wetlands were identified, excluding ponds (Table 13). The wetland acreage based on LLWW classification was 326.2 acres. Most (52%) of the wetland acreage was terrene wetland (Map 2). The remainder was mostly lotic wetland (40%). Only 8% of the wetland acreage was lentic.
From the landform perspective, basin wetlands predominated, accounting for 64% of the wetland acreage. Floodplain wetlands were next occupying 26% of the acreage, followed by flats at 6% (Map 3). Fringe wetlands made up nearly 4%, while slopes comprised 1%. Island wetlands accounted for less than 1%. Map 4 shows the distribution of wetlands by a combination of landscape position and landform. Considering water flow path, throughflow wetlands represented nearly half of the acreage (38% perennial and 8% intermittent) (Map 5). Outflow wetlands comprised 32% (22% perennial and 10% intermittent). Isolated types accounted for 20% and bidirectional flow types made up nearly 3% of the acreage, respectively.
For the 105 ponds identified (54.8 acres), 40% of the acreage was isolated, 38% throughflow (30% perennial and 8% intermittent), 22% outflow (14% intermittent and 8% perennial), and the remaining <1 % inflow.
30
Table 12. Wetlands classified by NWI types for the Rondout Reservoir Basin.
NWI Wetland Type Acreage Acreage
(within reservoir) (outside reservoir)
Lacustrine Wetlands 3.0 0.0
Palustrine Wetlands
Emergent - 64.5
Emergent/Forested - 2.1
Emergent/Scrub-Shrub 11.3
(subtotal Emergent) (0.0) (77.9)
Forested, Broad-leaved Deciduous - 30.0
Forested, Mixed - 91.0
Forested, Needle-leaved Evergreen - 90.9
(subtotal Forested) (0.0) (211.9)
Scrub-Shrub, Deciduous - 16.6
Scrub-Shrub, Evergreen - 0.8
Scrub-Shrub, Mixed - 10.9
(subtotal Scrub-Shrub) (0.0) (28.3)
Unconsolidated Bottom 0.0 54.8
--------------------------------------------- -------------- ------------
Palustrine Subtotal 0.0 372.9
Riverine Wetlands - 8.9
GRAND TOTAL (ALL WETLANDS) 3.0 381.8
31
Table 13. Wetlands in the Rondout Reservoir Basin classified by LLWW types.
Landscape Number
Position Landform Water Flow of Wetlands Acreage
Lentic (LE) Basin (BA) Bidirectional (BI) 2 6.8
Throughflow (TH) 1 14.8
(subtotal) (3) (21.7)
Flat (FL) Bidirectional (BI) 2 0.7
Throughflow (TH) 1 2.5
(subtotal) (3) (3.2)
Island (IL) Bidirectional (BI) 1 0.5
(Subtotal Lentic) (7) (25.3)
Lotic River
(LR) Fringe (FR) Throughflow (TH) 1 0.3
(Subtotal Lotic River) (1) (0.3)
Lotic Stream
(LS) Basin (BA) Throughflow (TH) 1 11.4
Throughflow-
Intermittent (TI) 5 20.5
(subtotal) (6) (31.9)
Flat (FL) Throughflow-
Intermittent (TI) 3 2.5
Floodplain (FP) Throughflow (TH) 21 82.9
Fringe (FR) Throughflow (TH) 8 11.1
Slope (SL) Throughflow (TH) 1 3.2
(Subtotal Lotic Stream) (39) (131.5)
Terrene (TE)
Basin (BA) Isolated (IS) 12 59.8
Outflow (OU) 8 71.2
Outflow Intermittent (OI) 4 23.1
(subtotal) (24) (154.1)
Flat (FL) Isolated (IS) 4 4.2
Outflow Intermittent (OI) 4 9.3
(subtotal) (8) (13.5)
Floodplain (FP) Isolated (IS) 1 0.5
Outflow (OU) 1 1.0
(subtotal) (2) (1.5)
(Subtotal Terrene) (34) (169.1)
TOTAL LLWWTypes* 81 326.2
*Does not include 105 ponds that totaled 54.8 acres.
Note: Subtotals may be slightly different than the sum of acreages shown due to computer round-off procedures.
32
Preliminary Assessment of Wetland Functions
The results for each wetland function for the Rondout Reservoir Basin are given in Table 14. Refer to the maps for locations of these wetlands; maps are hotlinked to the table.
More than 80% of the wetland acreage was predicted to be significant for four functions: surface water detention (93%), sediment retention (92%), nutrient transformation (83%), and streamflow maintenance (81%). Sixty-four percent of the acreage was deemed potentially significant for other wildlife habitat, while 41% was predicted important for shoreline stabilization. About a quarter of the wetland acreage was predicted as significant for fish habitat and habitat for waterfowl and waterbirds. An additional 12% of the acreage provided cover for streams, thereby moderating water temperatures important for aquatic life.
33
Table 14. Predicted wetland functions for the Rondout Reservoir Basin (excluding wetlands within the reservoir). Click on maps to view potential wetlands of significance for each function.
Predicted
Function Level Acreage Percent of Wetlands
Surface Water Detention High 141.0 37
(Map 6) Moderate 214.1 56
Streamflow Maintenance High 289.9 76
(Map 7) Moderate 17.3 5
Nutrient Transformation High 287.8 75
(Map 8) Moderate 29.5 8
Sediment Retention High 145.9 38
(Map 9) Moderate 204.5 54
Shoreline Stabilization High 147.8 39
(Map 10) Moderate 8.6 2
Fish Habitat High 2.5 1
(Map 11) Moderate 90.3 24
Shading 47.0 12
Waterfowl and Waterbird
Habitat (Map 12) High 37.6 10
Moderate 55.2 14
Other Wildlife Habitat High 110.7 29
(Map 13) Moderate 133.7 35
34
CATSKILL WATERSHED
Two reservoir basins occur within the Catskill watershed: Schoharie and Ashokan.
Schoharie Reservoir Basin Profile
Wetland Characterization
Wetlands by NWI Types
According to the NWI, the Schoharie Reservoir Basin had over 2,500 acres of wetlands, with only 2.8 acres within the reservoir (Table 15; Map 1). Wetland types were fairly even distributed among the basic types: forested wetlands (28% of the wetlands), emergent wetlands (27%), nonvegetated wetlands (26%), and scrub-shrub wetlands (20%). Deepwater habitats (e.g., lakes and reservoirs) totaled nearly 1,500 acres (1,307.7 acres of lacustrine including 1,167.2 acres in the reservoir, and 178.2 acres of riverine habitat).
Wetlands by LLWW Types
A total of 674 wetlands were identified, excluding ponds (Table 16). The wetland acreage based on LLWW classification was 1999.8 acres. Most (64%) of the wetland acreage was lotic wetland (Map 2; 55% lotic stream and 9% lotic river). The remainder was mostly terrene wetland (27%). Only 9% of the wetland acreage was lentic.
Floodplain wetlands and basin wetlands made up more than 80% of the wetland acreage (43% floodplain and 39% basin) (Map 3). Flat and fringe types each represented about 8% of the acreage. Slope wetlands accounted for slightly more than 1% of the acreage. Map 4 shows the distribution of wetlands by a combination of landscape position and landform. Considering water flow path, nearly three-quarters of the wetland acreage was throughflow (63% perennial and 10% intermittent) (Map 5). Outflow types represented nearly 20% (13% perennial and almost 7% intermittent). Isolated wetlands comprised nearly 7% of the acreage, while bidirectional flow and inflow types accounted for the remainder (nearly 2% for the former and less than 1% for the latter).
For the 688 ponds identified (452.3 acres), 48% of the acreage was throughflow (nearly 37% perennial and almost 12% intermittent), 30% isolated, 20% outflow (13% perennial and 7% intermittent), and about 1% inflow.
35
Table 15. Wetlands classified by NWI types for the Schoharie Reservoir Basin.
NWI Wetland Type Acreage Acreage
(within reservoir) (outside reservoir)
Lacustrine Wetlands 2.8 0.0
Palustrine Wetlands
Emergent - 615.1
Emergent/Scrub-Shrub - 63.7
(subtotal Emergent) (0.0) (678.8)
Forested, Broad-leaved Deciduous - 355.2
Forested, Mixed - 91.7
Forested, Needle-leaved Evergreen - 196.4
Forested, Dead - 47.6
Forested/Emergent - 11.9
Forested/Scrub-Shrub - 1.8
(subtotal Forested) (0.0) (703.6)
Scrub-Shrub, Deciduous- - 417.8
Scrub-Shrub, Evergreen - 10.3
Scrub-Shrub/Emergent - 54.3
Scrub-Shrub, Mixed - 23.2
(subtotal Scrub-Shrub) (0.0) (505.6)
Unconsolidated Bottom 0.0 539.7
Unconsolidated Shore 0.0 5.6
--------------------------------------------- -------------- ------------
Palustrine Subtotal 0.0 2,432.3
Riverine Wetlands 0.0 110.7
GRAND TOTAL (ALL WETLANDS) 2.8 2,543.0
36
Table 16. Wetlands in the Schoharie Reservoir Basin classified by LLWW types.
Landscape Number
Position Landform Water Flow of Wetlands Acreage
Lentic (LE)
Basin (BA) Bidirectional (BI) 7 32.4
Throughflow (TH) 11 74.9
(subtotal) (18) (107.3)
Flat (FL) Throughflow (TH) 2 80.0
(Subtotal Lentic) (20) (187.4)
Lotic River
(LR)
Floodplain (FP) Throughflow (TH) 32 123.4
Fringe (FR) Throughflow (TH) 33 46.5
(Subtotal Lotic River) (65) (169.9)
Lotic Stream
(LS)
Basin (BA) Throughflow (TH) 20 80.0
Throughflow-
Intermittent (TI) 57 156.1
(subtotal) (77) (236.1)
Flat (FL) Throughflow (TH) 1 9.4
Throughflow-
Intermittent (TI) 8 24.4
(subtotal) (9) (33.8)
Floodplain (FP) Throughflow (TH) 206 742.5
Fringe (FR) Throughflow (TH) 68 88.5
Throughflow-
Intermittent (TI) 2 5.1
(subtotal) (70) (93.6)
(Subtotal Lotic Stream) (362) (1,106.0)
Terrene (TE)
Basin (BA) Inflow (IN) 2 1.7
Isolated (IS) 96 111.7
Outflow (OU) 46 204.2
Outflow Intermittent (OI) 41 115.3
Throughflow (TH) 2 7.9
(subtotal) (187) (440.7)
Flat (FL) Isolated (IS) 13 14.1
Outflow (OU) 6 17.6
Outflow Intermittent (OI) 8 11.0
Throughflow
Intermittent (TI) 1 8.6
(subtotal) (28) (51.2)
Floodplain (FP) Isolated (IS) 1 0.1
37
Fringe (FR) Outflow (OU) 1 20.1
Island (IL) Outflow Intermittent (OI) 1 20.1
Slope (SL) Isolated (IS) 2 6.7
Outflow (OU) 5 13.8
Outflow Intermittent (OI) 2 3.8
(subtotal) (9) (24.3)
(Subtotal Terrene) (227) (536.5)
TOTAL LLWWTypes* 674 1,999.8
*Does not include 688 ponds that totaled 452.3 acres.
Note: Subtotals may be slightly different than the sum of acreages shown due to computer round-off procedures.
38
Preliminary Assessment of Wetland Functions
The results for each wetland function for the Schoharie Reservoir Basin are given in Table 17. Refer to the maps for locations of these wetlands; maps are hotlinked to the table.
Two functions were predicted to be performed at significant levels by more than 80% of the wetland acreage: surface water detention (89%) and sediment retention (85%). More than 50% of the wetland acreage was deemed important for five other functions: nutrient transformation (75%), provision of other wildlife habitat (68%), streamflow maintenance (62%), and shoreline stabilization (57%). The remaining functions -- provision of fish habitat and provision of waterfowl and waterbird habitat -- were projected to be performed at significant levels by roughly one-third of the wetland acreage (33% and 35%, respectively). Sixteen percent of the wetland acreage provided shading for streams potentially important for regulating water temperatures.
39
Table 17. Predicted wetland functions for the Schoharie Reservoir Basin (excluding wetlands within the reservoir). Click on maps to view potential wetlands of significance for each function.
Predicted
Function Level Acreage Percent of Wetlands
Surface Water Detention High 1,322.6 52
(Map 6) Moderate 950.5 37
Streamflow Maintenance High 1,255.3 49
(Map 7) Moderate 321.6 13
Nutrient Transformation High 1,413.4 56
(Map 8) Moderate 475.6 19
Sediment Retention High 1,247.7 49
(Map 9) Moderate 904.3 36
Shoreline Stabilization High 1,352.4 53
(Map 10) Moderate 110.4 4
Fish Habitat High 14.3 1
(Map 11) Moderate 805.5 32
Shading 395.9 16
Waterfowl and Waterbird
Habitat (Map 12) High 416.8 16
Moderate 490.3 19
Wood Duck 10.0 <1
Other Wildlife Habitat High 619.3 24
(Map 13) Moderate 1,109.3 44
40
Ashokan Reservoir Basin Profile
Wetland Characterization
Wetlands by NWI Types
According to the NWI, the Ashokan Reservoir Basin had more than 1,300 acres of wetlands including 24 acres in the reservoir (Table 18; Map 1). Forested wetlands, the predominant palustrine type with almost 600 acres, accounted for 45% of the wetlands. Nonvegetated wetlands (ponds and exposed shores) accounted for 22% of the wetlands. Emergent wetlands and scrub-shrub wetlands comprised 19% and 14% of the wetlands, respectively. Deepwater habitats (e.g., lakes and reservoirs) totaled over 8,400 acres (8,199.6 acres of lacustrine including 8,054.0 acres in the reservoir, and 203.9 acres of riverine habitat).
Wetlands by LLWW Types
A total of 390 wetlands were identified, excluding ponds (Table 19). The wetland acreage based on LLWW classification was 1,115.7 acres. Most (73%) of the wetland acreage was lotic wetland (Map 2; 51% lotic stream and 22% lotic river). The remainder was mostly terrene wetland (19%). Only 8% of the wetland acreage was lentic.
From the landform perspective, floodplain and basin wetlands were most extensive, accounting for about 56% and 30% of the wetland acreage, respectively (Map 3). Fringe wetlands accounted for 11% and flat wetlands 2%. Slope and island landforms collectively represented 1% of the wetland acreage. Map 4 shows the distribution of wetlands by a combination of landscape position and landform. Considering water flow path, 77% of the wetland acreage was throughflow (69% perennial and 7% intermittent (Map 5). Outflow accounted for 10% of the acreage (7% intermittent and 3% perennial). Isolated types comprised 9% of the acreage, whereas only 4% of the acreage had bidirectional flow.
For the 209 ponds identified (155.4 acres), 61% of the acreage was throughflow (56% perennial and 5% intermittent), 18% outflow (12% intermittent and 6% perennial), and 21% isolated.
41
Table 18. Wetlands classified by NWI types for the Ashokan Reservoir Basin.
NWI Wetland Type Acreage Acreage
(within reservoir) (outside reservoir)
Lacustrine Wetlands 3.2 0.0
Palustrine Wetlands
Emergent 0.6 223.9
Emergent/Scrub-Shrub - 32.1
(subtotal Emergent) (0.6) (256.0)
Forested, Broad-leaved Deciduous - 516.5
Forested, Mixed - 6.7
Forested, Needle-leaved Evergreen - 40.8
Forested, Dead - 18.4
Forested/Unconsolidated Bottom - 2.1
Forested/Scrub-Shrub - 15.0
(subtotal Forested) (0.0) (599.5)
Scrub-Shrub, Deciduous - 160.6
Scrub-Shrub, Evergreen - 0.8
Scrub-Shrub/Emergent - 21.6
Scrub-Shrub/Unconsolidated Shore - 1.9
(subtotal Scrub-Shrub) (0.0) (184.9)
Unconsolidated Bottom 18.6 189.2
Unconsolidated Shore 1.6 -
--------------------------------------------- -------------- ------------
Palustrine Subtotal 20.8 1,229.6
Riverine Wetlands 0.0 75.5
GRAND TOTAL (ALL WETLANDS) 24.0 1,305.1
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Table 19. Wetlands in the Ashokan Reservoir Basin classified by LLWW types.
Landscape Number
Position Landform Water Flow of Wetlands Acreage
Lentic (LE)
Basin (BA) Bidirectional (BI) 18 29.6
Throughflow Perennial (TH) 7 28.9
(subtotal) (25) (58.5)
Flat (FL) Bidirectional (BI) 2 2.9
Fringe (FR) Bidirectional (BI) 2 11.1
Throughflow (TH) 1 8.6
(subtotal) (3) (19.7)
Island (IL) Bidirectional (BI) 5 3.2
(Subtotal Lentic) (35) (84.3)
Lotic River
(LR)
Floodplain (FP) Throughflow (TH) 33 217.7
Fringe (FR) Throughflow (TH) 22 31.3
Island (IL) Throughflow (TH) 3 1.5
(Subtotal Lotic River) (58) (250.5)
Lotic Stream
(LS)
Basin (BA) Throughflow (TH) 5 32.8
Throughflow Intermittent (TI) 16 59.7
(subtotal) (21) (92.6)
Flat (FL) Throughflow (TH) 1 0.8
Throughflow Intermittent (TI) 4 3.8
(subtotal) (5) (4.6)
Floodplain (FP) Throughflow (TH) 88 394.7
Throughflow Intermittent (TI) 1 2.7
(subtotal) (89) (397.4)
Fringe (FR) Throughflow (TH) 49 54.7
Throughflow-
Intermittent (TI) 1 15.1
(subtotal) (50) (69.7)
Slope (SL) Throughflow (TH) 1 0.6
(Subtotal Lotic Stream) (166) (564.8)
Terrene (TE)
Basin (BA) Inflow (IN) 1 0.8
Isolated (IS) 88 93.0
Outflow Intemittent (OI) 16 53.7
Outflow Perennial (OU) 5 36.1
Throughflow Perennial (TH) 1 2.0
(subtotal) (111) (185.6)
43
Flat (FL) Inflow (IN) 1 1.4
Isolated (IS) 7 7.0
Outflow Intermittent (OI) 4 9.3
(subtotal) (12) (17.7)
Floodplain (FP) Isolated (IS) 4 3.4
Fringe (FR) Outflow (OU) 1 3.5
Slope (SL) Outflow Intermittent (OI) 3 5.8
(Subtotal Terrene) (131) (216.1)
TOTAL LLWWTypes* 390 1115.7
*Does not include 209 ponds that totaled 155.4 acres.
Note: Subtotals may be slightly different than the sum of acreages shown due to computer round-off procedures.
44
Preliminary Assessment of Wetland Functions
The results for each wetland function for the Ashokan Reservoir Basin are given in Table 20. Refer to the maps for locations of these wetlands; maps are hotlinked to the table.
Surface water detention was predicted to be performed at significant levels by 93% of the wetland acreage, while sediment retention was second-ranked with 89% of the acreage contributing to this function. Four other functions were performed at significant levels by more than 60% of the wetland acreage: nutrient transformation (79%), provision of other wildlife habitat (67%), streamflow maintenance (66%), and shoreline stabilization (64%). Less than 30% of the wetland acreage was deemed important for provision of fish habitat (23%) and provision of waterfowl and waterbird habitat (27%). Twenty-two percent of the acreage shaded streams and are potentially important for moderating water temperatures important for fish and other aquatic life.
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Table 20. Predicted wetland functions for the Ashokan Reservoir Basin (excluding wetlands within the reservoir). Click on maps to view potential wetlands of significance for each function.
Predicted
Function Level Acreage Percent of Wetlands
Surface Water Detention High 861.0 66
(Map 6) Moderate 347.1 27
Streamflow Maintenance High 534.3 41
(Map 7) Moderate 324.2 25
Nutrient Transformation High 684.0 52
(Map 8) Moderate 356.2 27
Sediment Retention High 818.9 63
(Map 9) Moderate 342.3 26
Shoreline Stabilization High 820.5 63
(Map 10) Moderate 16.0 1
Fish Habitat High 26.5 2
(Map 11) Moderate 276.2 21
Shading 291.3 22
Waterfowl and Waterbird
Habitat (Map 12) High 175.8 13
Moderate 170.6 13
Wood Duck 6.8 <1
Other Wildlife Habitat High 387.6 30
(Map 13) Moderate 479.9 37
46
Appropriate Use of this Report
The report provides a basic wetland characterization and a preliminary assessment of wetland functions for each NYC reservoir basin in the Delaware and Catskill watersheds. Keeping in mind the limitations mentioned previously, the results are an initial screening of the watershed's wetlands to designate wetlands that may have a significant potential to perform different functions. The targeted wetlands have been predicted to perform a given function at a significant level presumably important to the watershed's ability to provide that function. "Significance" is a relative term and is used in this analysis to identify wetlands that are likely to perform a given function at a level above that of wetlands not designated.
While the results are useful for gaining an overall perspective of a watershed's wetlands and their relative importance in performing certain functions, the report does not identify differences among wetlands of similar type and function. The latter information is often critical for making decisions about wetland acquisition and designating certain wetlands as more important for preservation versus others with the same classification.
The report is useful for general natural resource planning, as a screening tool for prioritization of wetlands (for acquisition or strengthened protection), as an educational tool (e.g., helping the public and nonwetland specialists better understand the functions of wetlands and the relationships between wetland characteristics and performance of individual functions), and for characterizing the differences among wetlands in terms of both form and function within a watershed.
Recommendations for Future Studies
1. Floodplains. While soil mapping may help identify these features, it may be worth limiting use of this landform to wetlands along higher order streams, with wetlands along lower order streams (orders 0,1, and 2) designated as lotic basins or flats depending on the duration of flooding. Alternatively, the landform could be limited to areas where broad valleys contain both wetland and upland plains or more simply to wetlands along "rivers" (polygonal streams). Streamside areas occupied solely by wetlands (no upland floodplain present) might be better classified as basins or flats rather than as floodplains. The present classification protocol described wetlands along rivers and low-gradient streams as floodplain types and those along intermittent streams as basins or flats. This should not, however, greatly effect the functional analysis as these types are accorded the same level of significance for most functions.
2. Headwater wetlands. It may be worth investigating whether this descriptor should be applied to wetlands along third-order streams in mountainous areas.
3. Correlation between NWI water regime and landform. Field work needs to be incorporated into future assessments to verify the following correlations: semipermanently flooded water regime (F) and fringe; seasonally flooded (C, E) and basin (including floodplain-basin); and temporarily flooded (A) and flat (including floodplain-flat). Some wetlands along reservoirs classified as basin wetlands (e.g., PEM1E) may be better described as fringe types if they are marshes. Relying on NWI water regimes for most landform classifications may lead to multiple
47
landform types within a single wetland. While this may be accurate in some cases (e.g., floodplains), it is worth looking at situations outside the floodplain to see if it is also the best way to classify these wetlands.
4. Intermittent vs. perennial streams. While the distinction is obvious given their definitions, it is often difficult to separate the two on the ground, especially in mountainous and hilly terrain without timely field inspection (e.g., multi-year field visits in late summer). We did notice possible errors in the digital data available for this study as we have on USGS topographic maps from other studies (e.g., intermittent streams designated as perennial streams). Some of the potential problems were based on perennial streams going to intermittent streams and small stretches of intermittent streams between much longer perennial streams. While these situations may be real, they do raise questions as to the classification accuracy of the source data.
48
References
Brinson, M. M. 1993. A Hydrogeomorphic Classification for Wetlands. U.S. Army Corps of Engineers, Washington, DC. Wetlands Research Program, Technical Report WRP-DE-4.
Cowardin, L. M., V. Carter, F. C. Golet, and E. T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service, Washington, DC. FWS/OBS-79/31.
Mitsch, W.J. and J.G. Gosselink. 2000. Wetlands. John Wiley and Sons, Inc., New York, NY.
Tiner, R.W. 1997a. Atlas of National Wetlands Inventory Maps for the Watersheds of the New York City Water Supply System. U.S. Fish and Wildlife Service, Hadley, MA. Prepared for the New York City Department of Environmental Protection, Bureau of Water Supply, Quality, and Protection, Valhalla, NY.
Tiner, R.W. 1997b. NWI Maps: What They Tell Us. National Wetlands Newsletter 19(2): 7-12. (Copy available from USFWS, ES-NWI, 300 Westgate Center Drive, Hadley, MA 01035)
Tiner, R.W. 1998. In Search of Swampland: A Wetland Sourcebook and Field Guide. Rutgers University Press, New Brunswick, NJ.
Tiner, R. W. 2000. Keys to Waterbody Type and Hydrogeomorphic-type Wetland Descriptors for U.S. Waters and Wetlands (Operational Draft). U.S. Fish and Wildlife Service, Northeast Region, Hadley, MA. November 2000.
Tiner, R.W. 2003a. Dichotomous Keys and Mapping Codes for Wetland Landscape Position, Landform, Water Flow Path, and Waterbody Type Descriptors. U.S. Fish and Wildlife Service, Northeast Region, Hadley, MA. September 2003.
Tiner, R.W. 2003b. Correlating Enhanced National Wetlands Inventory Data With Wetland Functions for Watershed Assessments: A Rationale for Northeastern U.S. Wetlands. U.S. Fish and Wildlife Service, Northeast Region, Hadley, MA.
Tiner, R., S. Schaller, and M. Starr. 1999. Wetland Characterization and Preliminary Assessment of Wetland Functions for the Boyd Corners and West Branch Sub-basins of the Croton Watershed, New York. U.S. Fish and Wildlife Service, Ecological Services, Northeast Region, Hadley, MA.
Tiner, R.W., H.C. Bergquist, and B.J. McClain. 2002. Wetland Characterization and Preliminary Assessment of Wetland Functions for the Neversink Reservoir and Cannonsville Reservoir Basins of the New York City Water Supply Watershed. U.S. Fish and Wildlife Service, Ecological Services, Northeast Region, Hadley, MA.
Tiner, R.W., C.W. Polzen, and B.J. McClain. 2004. Wetland Characterization and Preliminary
49
Assessment of Wetland Functions for the Croton Watershed of the New York City Water Supply Watershed. U.S. Fish and Wildlife Service, Ecological Services, Northeast Region, Hadley, MA.
50
AppendicesAppendix A. Dichotomous Keys and Mapping Codes for Wetland Landscape Position, Landform, Water Flow Path, and Waterbody Type Descriptors (Tiner 2003a). U.S. Fish and Wildlife Service
Dichotomous Keys and Mapping Codes for Wetland
Landscape Position, Landform, Water Flow Path, and
Waterbody Type Descriptors
September 2003Dichotomous Keys and Mapping Codes for Wetland Landscape Position,
Landform, Water Flow Path, and Waterbody Type Descriptors
Ralph W. Tiner
Regional Wetland Coordinator
U.S. Fish and Wildlife Service
National Wetlands Inventory Project
Northeast Region
300 Westgate Center Drive
Hadley, MA 01035
September 2003 This report should be cited as:
Tiner, R.W. 2003. Dichotomous Keys and Mapping Codes for Wetland Landscape Position, Landform, Water Flow Path, and Waterbody Type Descriptors. U.S. Fish and Wildlife Service, National Wetlands Inventory Program, Northeast Region, Hadley, MA. 44 pp. Table of Contents
Page
Section 1. Introduction 1
Need for New Descriptors 1
Background on Development of Keys 2
Use of the Keys 3
Uses of Enhanced Digital Database 3
Organization of this Report 4
Section 2. Wetland Keys 5
Key A-1: Key to Wetland Landscape Position 8
Key B-1: Key to Inland Landforms 11
Key C-1: Key to Coastal Landforms 14
Key D-1: Key to Water Flow Paths 15
Section 3. Waterbody Keys 18
Key A-2: Key to Major Waterbody Type 19
Key B-2: Key to River/Stream Gradient and Other Modifiers Key 20
Key C-2: Key to Lakes 22
Key D-2: Key to Ocean and Marine Embayments 23
Key E-2: Key to Estuaries 23
Key F-2: Key to Water Flow Paths 25
Key G-2: Key to Estuarine Hydrologic Circulation Types 26
Section 4. Coding System for LLWW Descriptors 27
Codes for Wetlands 27
Landscape Position 27
Lotic Gradient 27
Lentic Type 28
Estuary Type 28
Inland Landform 29
Coastal Landform 30
Water Flow Path 31
Other Modifiers 31
Codes for Waterbodies (Deepwater Habitats and Ponds) 32
Waterbody Type 32
Water Flow Path 36
Estuarine Hydrologic Circulation Type 36
Other Modifiers 36
Section 5. Acknowledgments 37
Section 6. References 37
Section 7. Glossary 40 1
Section 1. Introduction
A wide variety of wetlands have formed across the United States. To describe this diversity and to inventory wetland resources, government agencies and scientists have devised various wetland classification systems (Tiner 1999). Features used to classify wetlands include vegetation, hydrology, water chemistry, origin of water, soil types, landscape position, landform (geomorphology), wetland origin, wetland size, and ecosystem form/energy sources.
The U.S. Fish and Wildlife Service's wetland and deepwater habitat classification (Cowardin et al. 1979) is the national standard for wetland classification. This classification system emphasizes vegetation, substrate, hydrology, water chemistry, and certain impacts (e.g., partly drained, excavated, impounded, and farmed). These properties are important for describing wetlands and separating them into groups for inventory and mapping purposes and for natural resource management. They do not, however, include some abiotic properties important for evaluating wetland functions (Brinson 1993). Moreover, the classification of deepwater habitats is limited mainly to general aquatic ecosystem (marine, estuarine, lacustrine, and riverine) and bottom substrate type, with a few subsystems noted for riverine deepwater habitats. The Service's classification system would benefit from the application of additional descriptors that more fully encompass the range of characteristics associated with wetlands and deepwater habitats.
In the early 1990s, Mark Brinson created a hydrogeomorphic (HGM) classification system to serve as a foundation for wetland evaluation (Brinson 1993). He described the HGM system as "a generic approach to classification and not a specific one to be used in practice" (Brinson 1993, p. 2). This system emphasized the location of a wetland in a watershed (its geomorphic setting), its sources of water, and its hydrodynamics. The system was designed for evaluating similar wetlands in a given geographic area and for developing a set of quantifiable characteristics for "reference wetlands" rather than for inventorying wetland resources (Smith et al. 1995). A series of geographically focused models or "function profiles" for various wetland types have been created and are in development for use in functional assessment (e.g., Brinson et al. 1995, Ainslie et al. 1999, Smith and Klimas 2002).
Need for New Descriptors
The Service's National Wetlands Inventory (NWI) Program has produced wetland maps for 91 percent of the coterminous United States and 35 percent of Alaska. Digital data are available for 46 percent of the former area and for 18 percent of the latter. Although these data represent a wealth of information about U.S. wetlands, they lack hydrogeomorphic and other characteristics needed to perform assessments of wetland functions over broad geographic areas. Using geographic information system (GIS) technology and geospatial databases, it is now possible to predict wetland functions for watersheds - a major natural resource planning unit. Watershed managers could make better use of NWI data if additional descriptors (e.g., hydrogeomorphic-type attributes) were added to the current NWI database. Watershed-based preliminary 2
assessments of wetland functions could be performed. This new information would also permit more detailed characterizations of wetlands for reports and for developing scientific studies and lists of potential reference wetland sites.
Background on Development of Keys
Since the Cowardin et al. wetland classification system (1979) is the national standard and forms the basis of the most extensive wetland database for the country, it would be desirable to develop additional modifiers to enhance the current data. This would greatly increase the value of NWI digital data for natural resource planning, management, and conservation. Unfortunately, Brinson's "A Hydrogeomorphic Classification of Wetlands" (1993) was not designed for use with the Service's wetland classification. He used some terms from the Cowardin et al. system but defined them differently (e.g., Lacustrine and Riverine). Consequently, the Service needed to develop a set of hydrogeomorphic-type descriptors that would be more compatible with its system. Such descriptors would bridge the gap between these two systems, so that NWI data could be used to produce preliminary assessments of wetland functions based on characteristics identified in the NWI digital database. In addition, more descriptive information on deepwater habitats would also be beneficial. For example, identification of the extent of dammed rivers and streams in the United States is a valuable statistic, yet according to the Service's classification dammed rivers are classified as Lacustrine deepwater habitats with no provision for separating dammed rivers from dammed lacustrine waters. Differentiation of estuaries by various properties would also be useful for national or regional inventories.
Recognizing the need to better describe wetlands from the abiotic standpoint in the spirit of the HGM approach, the Service developed a set of dichotomous keys for use with NWI data (Tiner 1997b). The keys bridge the gap between the Service's wetland classification and the HGM system by providing descriptors for landscape position, landform, water flow path and waterbody type (LLWW descriptors) important for producing better characterizations of wetlands and deepwater habitats. The LLWW descriptors for wetlands can be easily correlated with the HGM types to make use of HGM profiles when they become available. The LLWW attributes were designed chiefly as descriptors for the Service's existing classification system (Cowardin et al. 1979) and to be applied to NWI digital data, but they can be used independently to describe a wetland or deepwater habitat. Consequently, there is some overlap with Cowardin et al. since some users may wish to use these descriptors without reference to Cowardin et al.
The first set of dichotomous keys was created to improve descriptions of wetlands in the northeastern United States (Tiner 1995a, b). They were initially used to enhance NWI data for predicting functions of potential wetland restoration sites in Massachusetts (Tiner 1995a, 1997a). Later, the keys were modified for use in predicting wetland functions for watersheds nationwide (Tiner 1997b, 2000). A set of keys for waterbodies was added to improve the Service's ability to characterize wetland and aquatic resources for watersheds.
The keys are periodically updated based on application in various physiographic regions. This version is an update of an earlier set of keys published in 1997 and 2000 (Tiner 1997b, 2000). 3
Relatively minor changes have been made, including the following: 1) added "drowned river-mouth" modifier to the Fringe and Basin landforms (for use in areas where rivers empty into large lakes such as the Great Lakes where lake influences are significant), 2) added "connecting channels" to river type (to address concerns in the Great Lakes to highlight such areas), 3) added "Throughflow-intermittent" water flow path (to separate throughflow wetlands along intermittent streams from those along perennial streams), 4) added "Throughflow-artificial" and "Outflow-artificial" to water flow path (to identify former "isolated" wetlands or fragmented wetlands that are now throughflow or outflow due to ditch construction), 5) revised the lake key to focus on permanently flooded deepwater sites (note: shallow and seasonally to intermittently flooded sites are wetlands) and added "open embayment" modifier, and 6) revised the estuary type key (consolidated some types). This version also clarifies that a terrene wetland may be associated with a stream where the stream does not periodically flood the wetland. In this case, the stream has relatively little effect on the wetland's hydrology. This is especially true for numerous flatwood wetlands. It also briefly discusses how the term "isolated" is applied relative to surface water and ground water interactions. In the near future, illustrations will be added to this document to aid users in interpretations.
Use of the Keys
Two sets of dichotomous keys (composed of pairs of contrasting statements) are provided - one for wetlands and one for waterbodies. Vegetated wetlands (e.g., marshes, swamps, bogs, flatwoods, and wet meadows) and periodically exposed nonvegetated wetlands (e.g., mudflats, beaches, and other exposed shorelines) should be classified using the wetland keys, while the waterbody keys should be used for permanent deep open water habitats (subtidal or >6.6 feet deep for nontidal waters). Some sites may qualify as both wetlands and waterbodies. A good example is a pond. Shallow ponds less than 20 acres in size meet the Service's definition of wetland, but they are also waterbodies. Such areas can be classified as both wetland and waterbody, if desirable. However, we recommend that ponds be classified using the waterbody keys. Another example would be permanently flooded aquatic beds in the shallow water zone of a lake. We have classified them using wetland hydrogeomorphic descriptors, yet they also clearly represent a section of the lake (waterbody). This approach has worked well for us in producing watershed-based wetland characterizations and preliminary assessments of wetland functions.
Uses of Enhanced Digital Database
Once they are added to existing NWI digital data, the LLWW characteristics (e.g., landscape position, landform, water flow path, and waterbody type) may be used to produce a more complete description of wetland and deepwater habitat characteristics for watersheds. The enhanced NWI digital data may then be used to predict the likely functions of individual wetlands or to estimate the capacity of an entire suite of wetlands to perform certain functions in a watershed. Such work has been done for several watersheds including Maine's Casco Bay watershed and the Nanticoke River and Coastal Bays watersheds in Maryland, the Delaware portion of the Nanticoke River, and numerous small watersheds in New York (see Tiner et al. 4
1999, 2000, 2001; Machung and Forgione 2002; Tiner 2002; see sample reports on the NWI website:http://wetlands.fws.gov for application of the LLWW descriptors). These characterizations are based on our current knowledge of wetland functions for specific types (Tiner 2003) and may be refined in the future, as needed, based on the applicable HGM profiles and other information. The new terms can also be used to describe wetlands for reports of various kinds including wetland permit reviews, wetland trend reports, and other reports requiring more comprehensive descriptions of individual wetlands.
Organization of this Report
The report is organized into seven sections: 1) Introduction, 2) Wetland Keys, 3) Waterbody Keys, 4) Coding System for LLWW Descriptors (codes used for classifying and mapping wetlands), 5) Acknowledgments, 6) References, and 7) Glossary. 5
Section 2. Wetland Keys
Three keys are provided to identify wetland landscape position and landform for individual wetlands: Key A for classifying the former and Keys B and C for the latter (for inland wetlands and coastal wetlands, respectively). A fourth key - Key D - addresses the flow of water associated with wetlands.
Users should first identify the landscape position associated with the subject wetland following Key A-1. Afterwards, using Key B-1 for inland wetlands and Key C-1 for salt and brackish wetlands, users will determine the associated landform. The landform keys include provisions for identifying specific regional wetland types such as Carolina bays, pocosins, flatwoods, cypress domes, prairie potholes, playas, woodland vernal pools, West Coast vernal pools, interdunal swales, and salt flats. Key D-1 addresses water flow path descriptors. Various other modifiers may also be applied to better describe wetlands, such as headwater areas; these are included in the four main keys.
Besides the keys provided, there are numerous other attributes that can be used to describe the condition of wetlands. Some examples are other descriptors that address resource condition could be ones that emphasize human modification, (e.g., natural vs. altered, with further subdivisions of the latter descriptor possible), the condition of wetland buffers, or levels of pollution (e.g., no pollution [pristine], low pollution, moderate pollution, and high pollution). Addressing wetland condition, however, was beyond our immediate goal of describing wetlands from a hydrogeomorphic standpoint. 6
Key A-1: Key to Wetland Landscape Position
This key allows characterization of wetlands based on their location in or along a waterbody, in a drainageway, or in isolation ("geographically isolated" - surrounded by upland).
1. Wetland is completely surrounded by upland (non-hydric soils).....................................Terrene
1. Wetland is not surrounded by upland but is connected to a waterbody of some kind.................2
2. Wetland is located in or along tidal salt or brackish waters (i.e., an estuary or ocean) including its periodically inundated shoreline (excluding areas formerly under tidal influence)....................3
2. Wetland is not periodically inundated by salt or brackish tides..................................................4
3. Wetland is located in or along the ocean........................................................................Marine Go to Key C-1 for coastal landform
3. Wetland is located in or along an estuary (typically a semi-enclosed basin or tidal river where fresh water mixes with sea water)..................................................................................Estuarine Go to Key E-2 for Estuary Type, then to Key C-1 for coastal landform
Note: If area was formerly connected to an estuary but now is completely cut-off from tidal flow, consider as one of inland landscape positions - Terrene, Lentic, or Lotic, depending on current site characteristics. Such areas should be designated with a modifier to identify such wetlands as "former estuarine wetland." Lands overflowed infrequently by tides such as overwash areas on barrier islands are considered Estuarine. Tidal freshwater wetlands contiguous to salt/brackish/oligohaline tidal marshes are also considered Estuarine, whereas similar wetlands just upstream along strictly fresh tidal waters are considered Lotic.
4. Wetland is located in or along a lake or reservoir (permanent waterbody where standing water is typically much deeper than 6.6 feet at low water), including streamside wetlands in a lake basin and wetlands behind barrier islands and beaches with open access to a lake.............Lentic Go to Key C-2 for Lake Type
Then Go to Key B-1 for inland landform
Note: Lentic wetlands consist of all wetlands in a lake basin (i.e., the depression containing the lake), including lakeside wetlands intersected by streams emptying into the lake. The upstream limit of lentic wetlands is defined by the upstream influence of the lake which is usually approximated by the limits of the basin within which the lake occurs. The streamside lentic wetlands are designated as "Throughflow," thereby emphasizing the stream flow through these wetlands. Other lentic wetlands are typically classified as "Bidirectional-nontidal" since water tables rise and fall with lake levels during the year. Tidally-influenced freshwater lakes have "Bidirectional-tidal" flow. 7
Modifiers: Natural, Dammed River Valley, Other Dammed - see Key C-2 for others.
4. Wetland does not occur along this type of waterbody...............................................................5
5. Wetland is located in a river or stream (including in-stream ponds), within its banks, or on its active floodplain and is periodically flooded by the river or stream...............................................6
5. Wetland is not located in a river or stream or on its active floodplain............................Terrene
Note: These wetlands may occur: (1) on a slope or flat, or in a depression (including ponds, potholes, and playas) lacking a stream but contiguous to a river or stream, (2) on a historic (inactive) floodplain, or (3) in a landscape position crossed by a stream (e.g., an entrenched stream), but where the stream does not periodically inundate the wetland. Go to Key B-1 for inland landform
6. Wetland is the source of a river or stream but this watercourse does not extend through the wetland............................................................................................................................Terrene
Modifiers: May include Headwater for wetlands that are sources of streams and Estuarine Discharge or Marine Discharge for wetlands whose outflow goes directly to an estuary or the ocean, respectively.
6. Wetland is located in a river or stream, within its banks, or on its active floodplain..................7
7. Wetland is associated with a river (a broad channel mapped as a polygon or 2-lined watercourse on a 1:24,000 U.S. Geological Survey topographic map) or its active floodplain........ ..................................................................................................................................Lotic River
Go to Couplet "a" below
(Also see note under first couplet #3 - Lentic re: streamside wetlands in lake basins)
7. Wetland is associated with a stream (a.linear or single-line watercourse on a 1:24,000 U.S. Geological Survey topographic map) or its active floodplain....................................Lotic Stream
Go to Couplet "a" below
(Also see note under first couplet #3 - Lentic re: streamside wetlands in lake basins)
Note: Artificial drainageways (i.e., ditches) are not considered part of the Lotic classification, whereas channelized streams are part of the Lotic landscape position.
Modifiers: Headwater (wetlands along first-order streams and possibly second-order streams and large wetlands in upper portion of watershed believed to be significant groundwater discharge sites) and Channelized (excavated stream course). 8
a. Water flow is under tidal influence (freshwater tidal wetlands)...............Tidal Gradient Go to Key B-1 for inland landform
a. Water flow is not under tidal influence (nontidal)..........................................................b
b. Water flow is dammed, yet still flowing downstream, at least seasonally.........................
................................................................................................................Dammed Reach Go to Key B-1 for inland landform
Modifiers: Lock and Dammed, Run-of-River Dam, Beaver Dam, and Other Dam (see Waterbody Key B-2 for further information).
b. Water flow is unrestricted.............................................................................................c
c. Water flow is intermittent during the year...................................Intermittent Gradient Go to Key B-1 for inland landform
c. Water flow is perennial (year-round)............................................................................d
d. Water flow is generally rapid due to steep gradient; typically little or no floodplain development; watercourse is generally shallow with rock, cobbles, or gravel bottoms; first- and second-order "streams" in hilly to mountainous terrain; part of Cowardin's Upper Perennial Subsystem..........................................................................High Gradient Go to Key B-1 for inland landform
d. Watercourse characteristics are not so; "stream" order greater than 2 in hilly to mountainous terrain..........................................................................................................e
e. Water flow is generally slow; typically with extensive floodplain; water course shallow or deep with mud or sand bottoms; typically fifth and higher order "streams", but includes lower order streams in nearly level landscapes such as the Great Lakes Plain (former glacial lakebed) and the Coastal Plain, and ditches; the lower order streams may lack significant floodplain development); Cowardin's Lower Perennial subsystem.....................
...................................................................................................................Low Gradient Go to Key B-1 for inland landform
e. Water flow is fast to moderate; with little to some floodplain; usually third-, fourth- and higher order "streams" associated with hilly to mountainous terrain; part of Cowardin's Upper Perennial Subsystem...................................................Middle Gradient Go to Key B-1 for inland landform9
Key B-1: Key to Inland Landforms
1. Wetland occurs on a noticeable slope (e.g., greater than a 2 percent slope)........Slope Wetland Go to Key D-1 for water flow path
Modifiers can be applied to Slope Wetlands to designate the type of inflow or outflow as Channelized Inflow or Outflow (intermittent or perennial, stream or river), Nonchannelized Inflow or Outflow (wetland lacking stream, but connected by observable surface seepage flow), or Nonchannelized-Subsurface Inflow or Outflow (suspected subsurface flow from or to a neighboring wetland upslope or downslope, respectively).
1. Wetland does not occur on a distinct slope...............................................................................2
2. Wetland forms an island....................................................................................Island Wetland
(Go to Key D-1 for water flow path)
Note: Can designate an island formed in a delta at the mouth of a river or stream as a Delta Island Wetland; other islands are associated with landscape positions (e.g., lotic river island wetland, lotic stream island wetland, lentic island wetland, or terrene island pond wetland). Vegetation class and subclass from Cowardin et al. 1979 should be applied to characterize the vegetation of these wetland islands; vegetation is assumed to be rooted unless designated by a modifier - "Floating Mat" to indicate a floating island.
2. Wetland does not form an island..............................................................................................3
3. Wetland occurs within the banks of a river or stream or along the shores of a pond, lake, or island, or behind a barrier beach or island, and is either: (1) vegetated and typically permanently inundated, semipermanently flooded (including their tidal freshwater equivalents plus seasonally flooded-tidal palustrine emergent wetlands which tend to be flooded frequently by the tides) or otherwise flooded for most of the growing season, or permanently saturated due to this location or (2) a nonvegetated bank or shore that is temporarily or seasonally flooded ......Fringe Wetland Go to Couplet "a" below for Types of Fringe Wetlands
Then Go to Key D-1 for water flow path
Attention: Seasonally to temporarily flooded vegetated wetlands along rivers and streams (including tidal freshwater reaches) are classified as either Floodplain, Basin, or Flat landforms - see applicable categories.
a. Wetland forms along the shores of an upland island within a lake, pond, river, or
stream..................................................................................................................b
a. Wetland does not form along the shores of an island.....................................................d
b. Wetland forms behind a barrier island or beach spit along a lake...............Lentic Barrier Island Fringe Wetland or Lentic Barrier Beach Fringe Wetland10
Modifier: Drowned River-mouth
b. Wetland forms along another type of island...................................................................c
c. Wetland forms along an upland island in a river or stream...................Lotic River Island Fringe Wetland or Lotic Stream Island Fringe Wetland
c. Wetland forms along an upland island in a lake or pond...................Lentic Island Fringe Wetland or Terrene Pond Island Fringe Wetland
d. Wetland forms in or along a river or stream..........................Lotic River Fringe Wetland or Lotic Stream Fringe Wetland
d. Wetland forms in or along a pond or lake.....................................................................e
e. Wetland forms along a pond shore.................................................................................f
e. Wetland forms along a lake shore.................................................Lentic Fringe Wetland
Modifier: Drowned River-mouth
f. Wetland occurs along an in-stream pond.........................................Lotic River or Stream Fringe Pond Wetland Throughflow
f. Wetland occurs in another type of pond.............................Terrene Fringe Pond Wetland
Note: Vegetation is assumed to be rooted unless designated by a modifier to indicate a floating mat (Floating Mat).
3. Wetland does not exist along these shores................................................................................4
4. Wetland occurs on an active floodplain (alluvial processes in effect)........................Floodplain Wetland* (could specify the river system, if desirable). Go to Key D-1 for water flow path
Sub-landforms are listed below.
a. Wetland forms along the shores of a river island....................Floodplain Island Wetland
a. Wetland is not along an island.......................................................................................b
b. Wetland forms in a depressional feature on a floodplain.........Floodplain Basin Wetland or Floodplain Oxbow Wetland (a special type of depression)
b. Wetland forms on a broad nearly level terrace...........................Floodplain Flat Wetland
*Note: Questionable floodplain areas may be verified by consulting soil surveys and locating the presence of alluvial soils, e.g., Fluvaquents or Fluvents, or soils with Fluvaquentic subgroups. While most Floodplain wetlands will have a Throughflow water flow path; others may be designated, e.g., Inflow, Outflow, or Isolated. Former floodplain wetlands are classified as Basins or Flats and designated as former floodplain.
Modifiers: Partly Drained; Confluence wetland - wetland at the intersection of two or more streams; River-mouth or stream-mouth wetland - wetland at point where a river and 11
stream empties into lake; Meander scar wetland - floodplain basin wetland, the remnant of a former river meander.
4. Wetland does not occur on an active floodplain........................................................................5
5. Wetland occurs on an interstream divide (interfluve)...................................Interfluve Wetland or specify regional types of interfluve wetlands, for example: Carolina Bay Interfluve Wetland, Pocosin Interfluve Wetland, and Flatwood Interfluve Wetland (Southeast). Sub-landforms are listed below. Go to Key D-1 for water flow path
a. Wetland forms in a depressional feature................................... Interfluve Basin Wetland
a. Wetland forms on a broad nearly level terrace ............................Interfluve Flat Wetland
Modifiers: Partly Drained.
5. Wetland does not occur on an interfluve..................................................................................6
6. Wetland exists in a distinct depression in various positions on the landscape (i.e., surrounded by upland, along smaller rivers and streams, along in-stream ponds, along lake shores, or on former floodplains or interfluves)............ Basin Wetland or Basin Wetland Former Floodplain (including Basin Oxbow Wetland Former Floodplain) or Basin Wetland Former Interfluve. Can specify regional types: Carolina Bay Basin Wetland and Pocosin Basin Wetland (Atlantic Coastal Plain), Cypress Dome Basin Wetland (Florida), Prairie Pothole Basin Wetland (Upper Midwest), "Salt Flat" Basin Wetland (arid West), Playa Basin Wetland (Southwest), West Coast Vernal Pool Basin Wetland (California and Pacific Northwest), Interdunal Basin Wetland (sand dunes), Woodland Vernal Pool Basin Wetland (forests throughout the country), Polygonal Basin Wetland (Alaska), Sinkhole Basin Wetland (karst/limestone regions), Pond Wetland Basin (throughout country), or some type of Island Basin Wetland for basin wetlands on islands. Go to Key D-1 for water flow path
Modifiers may be applied to indicate artificially created basins due to beaver activity or human actions or artificially drained basins including: Beaver (beaver-created); wetlands created for various purposes or unintentionally formed due to human activities - may want to specify purpose like Aquaculture (e.g., fish and crayfish), Wildlife management (e.g., waterfowl impoundments), and Former floodplain, or to designate former salt marsh that is now nontidal (Former estuarine wetland). Other modifiers may be applied to designate the type of inflow or outflow as Channelized (intermittent or perennial, stream or river), Nonchannelized-wetland (contiguous wetland lacking stream), or Nonchannelized-subsurface flow (suspected subsurface flow to neighboring wetland), or to identify a headwater basin (Headwater) or a drainage divide wetland that discharges into two or more watershed (Drainage divide), or to denote a spring-fed wetland (Spring-fed), a wetland bordering a pond (Pond basin wetland) and a wetland bordering an upland 12
island in a pond (Pond island border). For lotic basin wetlands, consider additional modifiers such as Confluence wetland - wetland at the intersection of two or more streams; River-mouth or Stream-mouth wetland - wetland at point where a river and a stream empties into a lake. For lentic basins associated with the Great Lakes, possibly identify Drowned River-mouth wetlands where mouth extends into the lake basin. Partly drained may be used for ditched/drained wetlands.
6. Wetland exists in a relatively level area.................................................................Flat Wetland or specify regional types of flat wetlands, for example: Salt Flat Wetland (in the Great Basin) or flats that are fragments of once-larger interfluve flats or former floodplains: Flat Wetland, Former Interfluve or Flat Wetland, Former Floodplain. Go to Key D-1 for water flow path
Note: If desirable, a modifier for drained flats can be applied (Partly drained). Other modifiers can be applied to designate the type of inflow or outflow as Channelized (intermittent or perennial, stream or river), Nonchannelized-wetland (contiguous wetland lacking stream), or Nonchannelized-subsurface flow (suspected subsurface flow to neighboring wetland). For lotic flat wetlands, consider additional modifiers such as confluence wetland - wetland at the intersection of two or more streams; river-mouth or stream-mouth wetland - wetland at point where a river and a stream empties into a lake.
Key C-1: Key to Coastal Landforms
1. Wetland forms a distinct island in an inlet, river, or embayment........................Island Wetland Go to Key D-1 for water flow path
a. Occurs in a delta...........................................................................Delta Island Wetland
(Could identify flood delta and ebb delta islands for tidal inlets if desirable.)
a. Occurs elsewhere either in a river or an embayment ...................................................b
b. Occurs in a river.............................................................................River Island Wetland
b. Occurs in a coastal embayment.........................................................Bay Island Wetland
1. Wetland does not form such an island, but occurs behind barrier islands and beaches, or along the shores embayments, rivers, streams, and islands.....................................................................2
2. Wetland occurs along the shore, contiguous with the estuarine waterbody.......Fringe Wetland Go to Key D-1 for water flow path
a. Occurs behind a barrier island or barrier beach spit...........Barrier Island Fringe Wetland or Barrier Beach Fringe Wetland [Modifier for overwash areas: Overwash]
a. Occurs elsewhere..........................................................................................................b 13
b. Occurs along a coastal embayment or along an island in a bay.........Bay Fringe Wetland or Bay Island Fringe Wetland or Coastal Pond Fringe Wetland (a special type of embayment, typically with periodic connection to the ocean unless artificially connected by a bulkheaded inlet) or Coastal Pond Island Fringe Wetland
b. Occurs elsewhere..........................................................................................................c
c. Occurs along a coastal river or along an island in a river................River Fringe Wetland or River Island Fringe Wetland
c. Occurs elsewhere.........................................................................................................d
d. Occurs along an oceanic island...........................................Ocean Island Fringe Wetland
d. Occurs along the shores of exposed rocky mainland................Headland Fringe Wetland
2. Wetland is separated from main body of marsh by natural or artificial means; the former may be connected by a tidal stream extending through the upland or by washover channels (e.g., estuarine intertidal swales), whereas the latter occurs in an artificial impoundment or behind a road or railroad embankment where tidal flow is at least somewhat restricted........Basin Wetland Go to Key D-1 for water flow path
Modifiers may be applied to separate natural from created basins (managed fish and wildlife areas; aquaculture impoundments; salt hay diked lands; tidally restricted-road, and tidally restricted-railroad), and for other situations, as needed.
Key D-1: Key to Water Flow Paths
1. Wetland is periodically flooded by tides......................................................Bidirectional-tidal
See Key F-2 for additional descriptors based on tidal ranges (i.e., macrotidal, mesotidal, and microtidal).
1. Wetland is not flooded by tides...............................................................................................2
2. Water levels fluctuate due to lake influences or to variable river levels, but water does not flow through this wetland.............................................................................Bidirectional-nontidal
Note: Lentic wetlands with streams running through them are classified as Throughflow to emphasize this additional water source, while lentic wetlands located in coves or fringing the high ground would typically be classified as Bidirectional-Nontidal. Similarly, many floodplain wetlands are throughflow types, while some are connected to the river through a single channel in which water rises and falls with changing river levels. The water flow path of the latter types is best classified as bidirectional-nontidal. 14
2. Wetland is not subject to lake influences.................................................................................3
3. Wetland is formed by paludification processes where in areas of low evapotranspiration and high rainfall, peat moss moves uphill creating wetlands on hillslopes (i.e., wetland develops upslope of primary water source)..................................................................................Paludified
3. Wetland is not formed by paludification processes...................................................................4
4. Wetland receives surface or ground water from a stream, other waterbody or wetland (i.e., at a higher elevation) and surface or ground water passes through the subject wetland to a stream, another wetland, or other waterbody at a lower elevation; a flow-through system....Throughflow, Throughflow-intermittent*, Throughflow-entrenched*, or Throughflow-artificial*
Modifiers: Groundwater-dominated throughflow wetlands can be separated from Surface water-dominated throughflow wetlands.
*Note: Throughflow-intermittent is to be used with throughflow wetlands along intermittent streams; Throughflow-entrenched indicates that stream flow is through a wetland but the stream is deeply cut and does not overflow into the wetland (therefore the stream is, for practical purposes, separate from the wetland) - this water flow path is intended to be used with Terrene wetlands in this situation; Throughflow-artificial is used to designate wetlands where throughflow is human-caused - usually to indicate connection of Terrene wetlands to other Terrene wetlands and waters by ditches and not by streams either natural or channelized
4. Water does not pass through this wetland to other wetlands or waters....................................5
5. There is no surface or groundwater inflow from a stream, other waterbody, or wetland (i.e., no documented surface or ground water inflow from a wetland or other waterbody at a higher elevation) and no observable or known outflow of surface or ground water to other wetlands or waters..............................................................................................................................Isolated
Attention: In most applications, isolation is interpreted as "geographically isolated" since groundwater connections are typically unknown for specific wetlands. For practical purposes then," isolated" means no obvious surface water connection to other wetlands and waters. If hydrologic data exist for a locale that documents groundwater linkages, such wetlands should be identified as either outflow. inflow, or throughflow with a "Groundwater-dominated" modifier and not be identified as isolated unless the whole network of wetlands is not connected to a stream or river. In the latter case, the network is a collection of interconnected isolated wetlands.
5. Wetland is not hydrologically or geographically isolated..........................................................6
6. Wetland receives surface or ground water inflow from a wetland or other waterbody 15
(perennial or intermittent) at a higher elevation and there is no observable or known significant outflow of surface or ground water to a stream, wetland or waterbody at a lower elevation ..........................................................................................................................................Inflow
Modifiers: Groundwater-dominated inflow wetlands can be separated from Surface water-dominated inflow wetlands; Human-caused (usually to indicate connection of Terrene wetlands to other Terrene wetlands and waters [e.g., Inflow human-caused] by ditches and not by streams either natural or channelized).
6. Wetland receives no surface or ground water inflow from a wetland or permanent waterbody at a higher elevation (may receive flow from intermittent streams only) and surface or ground water is discharged from this wetland to a stream, wetland, or other waterbody at a lower elevation.......................................................................................Outflow or Outflow-artificial*
Modifiers: Groundwater-dominated outflow wetlands can be separated from Surface water-dominated outflow wetlands. Might consider separating perennial outflow (Outflow-perennial) from intermitttent outflow (Outflow-intermittent), if interested.
*Note: Outflow-artificial is usually used to indicate outflow from formerly isolated wetlands resulting by ditches. 16
Section 3. Waterbody Keys
These keys are designed to expand the classification of waterbodies beyond the system and subsystem levels in the Service's wetland classification system (Cowardin et al. 1979). Users are advised first to classify the waterbody in one of the five ecosystems: 1) marine (open ocean and associated coastline), 2) estuarine (mixing zone of fresh and ocean-derived salt water), 3) lacustrine (lakes, reservoirs, large impoundments, and dammed rivers), 4) riverine (undammed rivers and tributaries), and 5) palustrine (e.g., nontidal ponds) and then apply the waterbody type descriptors below.
Five sets of keys are given. Key A-2 helps describe the major waterbody type. Key B-2 identifies different stream gradients for rivers and streams. It is similar to the subsystems of Cowardin's Riverine system, but includes provisions for dammed rivers to be identified as well as a middle gradient reach similar to that of Brinson's hydrogeomorphic classification system. The third key, Key C-2, addresses lake types, while Keys D-2 and E-2 further define ocean and estuary types, respectively. Key F-2 is a key to water flow paths of waterbodies. Key G-2 is for describing general circulation patterns in estuaries. The coastal terminology applies concepts of coastal hydrogeomorphology.
Besides the keys provided, there are numerous other attributes that can be used to describe the condition of waterbodies. Some examples are other descriptors that address resource condition could be ones that emphasize human modification, (e.g., natural vs. altered, with further subdivisions of the latter descriptor possible), the condition of waterbody buffers (e.g., stream corridors), or levels of pollution (e.g., no pollution [pristine], low pollution, moderate pollution, and high pollution). 17
Key A-2. Key to Major Waterbody Type
1. Waterbody is predominantly flowing water..............................................................................2
1. Waterbody is predominantly standing water.............................................................................7
Note: Fresh waterbodies may be tidal; if so, waterbody is classified as a Tidal Lake or Tidal Pond using criteria below to separate lakes from ponds.
2. Flow is unidirectional and waterbody is a river, stream, or similar channel...............................3
2. Flow is tidal (bidirectional) at least seasonally; waterbody is an ocean, embayment, river, stream, or lake............................................................................................................................4
3. Waterbody is a polygonal feature on a U.S. Geological Survey map or a National Wetlands Inventory Map (1:24,000/1:25,000)......................................................................................River
3. Waterbody is a linear feature on such maps....................................................................Stream
Go to River/Stream Gradient Key - Key B-2 - for other modifiers
4. Waterbody is freshwater..........................................................................................................5
4. Waterbody is salt or brackish...................................................................................................6
5. Waterbody is a polygonal feature on a U.S. Geological Survey map or a National Wetlands Inventory Map (1:24,000/1:25,000)......................................................................................River
5. Waterbody is a linear feature on such maps....................................................................Stream
Go to River/Stream Gradient Key - Key B-2 - for other modifiers
6. Part of a major ocean or its associated embayment (Marine system of
Cowardin et al. 1979) .........................................................................................................Ocean
Go to Ocean Key - Key D-2
6. Part of an estuary where fresh water mixes with salt water (Estuarine system of
Cowardin et al. 1979).......................................................................................................Estuary
Go to Estuary Key - Key E-2
7. Waterbody is freshwater..........................................................................................................8
7. Waterbody is salt or brackish and tidal...................................................................................10
8. Waterbody is permanently flooded and deep (>than 6.6 ft at low water), excluding small 18
"kettle or bog ponds" (i.e., usually less than 5 acres in size and surrounded by bog vegetation)...........................................................................................................................Lake
Go to Lake Key - Key C-2
8. Waterbody is shallow (< 6.6 ft at low water) or a small "kettle or bog pond" (with deeper water).........................................................................................................................................9
9. Waterbody is small (< 20 acres)........................................................................................Pond
Separate natural from artificial ponds, then add other modifiers like the following. Some
examples of modifiers for ponds: b