This data set represents the extent, approximate location and type of wetlands and deepwater habitats in the United States and its Territories. These data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979). The National Wetlands Inventory - Version 2, Surface Waters and Wetlands Inventory was derived by retaining the wetland and deepwater polygons that compose the NWI digital wetlands spatial data layer and reintroducing any linear wetland or surface water features that were orphaned from the original NWI hard copy maps by converting them to narrow polygonal features. Additionally, the data are supplemented with hydrography data, buffered to become polygonal features, as a secondary source for any single-line stream features not mapped by the NWI and to complete segmented connections. Wetland mapping conducted in WA, OR, CA, NV and ID after 2012 and most other projects mapped after 2015 were mapped to include all surface water features and are not derived data. The linear hydrography dataset used to derive Version 2 was the U.S. Geological Survey's National Hydrography Dataset (NHD). Specific information on the NHD version used to derive Version 2 and where Version 2 was mapped can be found in the 'comments' field of the Wetlands_Project_Metadata feature class. Certain wetland habitats are excluded from the National mapping program because of the limitations of aerial imagery as the primary data source used to detect wetlands. These habitats include seagrasses or submerged aquatic vegetation that are found in the intertidal and subtidal zones of estuaries and near shore coastal waters. Some deepwater reef communities (coral or tuberficid worm reefs) have also been excluded from the inventory. These habitats, because of their depth, go undetected by aerial imagery. By policy, the Service also excludes certain types of "farmed wetlands" as may be defined by the Food Security Act or that do not coincide with the Cowardin et al. definition. Contact the Service's Regional Wetland Coordinator for additional information on what types of farmed wetlands are included on wetland maps. This dataset should be used in conjunction with the Wetlands_Project_Metadata layer, which contains project specific wetlands mapping procedures and information on dates, scales and emulsion of imagery used to map the wetlands within specific project boundaries. Please reference the metadata for contact information.

Note that due to the quantity and complexity of the data there is scale dependent rendering enabled. The vector data only draws when zoomed in to 1:250,000 map scale or larger. To view the wetlands data at a smaller scale utilize the Wetlands Raster service (https://www.fws.gov/wetlandsmapservice/rest/services/Wetlands_Raster/ImageServer) to display generalized wetlands at all scales.. For specific questions or assistance please email wetlands_team@fws.gov.For more information visit: https://www.fws.gov/wetlands/index.htmlView Wetlands Data on the Wetlands Mapper at: https://www.fws.gov/wetlands/Data/Mapper.htmlWetlands Web Services are available at: https://www.fws.gov/wetlands/Data/Web-Map-Services.htmlWetlands Data available as a KML at: https://www.fws.gov/wetlands/Data/Google-Earth.htmlWetlands Data Downloads available at: https://www.fws.gov/wetlands/Data/Data-Download.htmlWetland Data Standards available at: https://www.fws.gov/wetlands/Data/Data-Standards.htmlWetland Codes available at: https://www.fws.gov/wetlands/Data/Wetland-Codes.htm

Please note that, due to the large size, the Informational Freshwater Wetland Mapping layer cannot be download in shapefile format.The Informational Freshwater Wetland Mapping layer is only intended to be used for informational purposes in identifying the general location and extent of freshwater wetland areas of any size throughout the state. Informational Freshwater Wetland Mapping is not regulatory.The Freshwater Wetlands Act changed in 2022 such that wetlands greater than 12.4 acres in size are regulated regardless of their mapping status. In addition to larger wetlands, the Freshwater Wetlands Act regulates smaller wetlands of “unusual importance” if they meet one of eleven criteria described in the law and regulation. While maps contained on the Environmental Resource Mapper provide information on the potential locations of wetlands, the only definitive way to determine if a particular parcel or property contains regulated wetlands outside the Adirondack Park is to request a jurisdictional determination through DEC’s website (https://dec.ny.gov/nature/waterbodies/wetlands/freshwater-wetlands-program).The Freshwater Wetlands Act regulates most development activities located in the wetland or within a regulated “adjacent area.” This adjacent area is a minimum of 100 feet but may be extended for a limited number of particularly sensitive wetlands. Not all activities in and near wetlands are regulated. There are many exempt activities that landowners may undertake without permits. However, if you are not sure of which activities require permits near New York State regulated wetlands, please contact your regional DEC office.Wetlands are classified from Class I (which provide the most benefits) to Class IV (which provide fewer benefits). The classification is based on the work that wetlands do, such as storing flood water and providing wildlife habitat. The system for classifying wetlands is contained in regulation (6 NYCRR Part 664) and the classification of individual wetlands is determined as part of the jurisdictional determination process.For additional information on NYS Freshwater Wetlands, see DEC"s website (https://dec.ny.gov/nature/waterbodies/wetlands/freshwater-wetlands-program).For information on wetlands inside the Adirondack Park, please contact the Adirondack Park Agency.For information on wetlands regulated under federal law, please contact the United State Army Corps of Engineers.Contact for this DataDFW, Bureau of Ecosystem Health625 BroadwayAlbany, NY 12233Phone: 518-402-8920fw.ecohealth@dec.ny.gov

This data set represents the extent, approximate location and type of wetlands and deepwater habitats in the United States and its Territories. These data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979). The National Wetlands Inventory - Version 2, Surface Waters and Wetlands Inventory was derived by retaining the wetland and deepwater polygons that compose the NWI digital wetlands spatial data layer and reintroducing any linear wetland or surface water features that were orphaned from the original NWI hard copy maps by converting them to narrow polygonal features. Additionally, the data are supplemented with hydrography data, buffered to become polygonal features, as a secondary source for any single-line stream features not mapped by the NWI and to complete segmented connections. Wetland mapping conducted in WA, OR, CA, NV and ID after 2012 and most other projects mapped after 2015 were mapped to include all surface water features and are not derived data. The linear hydrography dataset used to derive Version 2 was the U.S. Geological Survey's National Hydrography Dataset (NHD). Specific information on the NHD version used to derive Version 2 and where Version 2 was mapped can be found in the 'comments' field of the Wetlands_Project_Metadata feature class. Certain wetland habitats are excluded from the National mapping program because of the limitations of aerial imagery as the primary data source used to detect wetlands. These habitats include seagrasses or submerged aquatic vegetation that are found in the intertidal and subtidal zones of estuaries and near shore coastal waters. Some deepwater reef communities (coral or tuberficid worm reefs) have also been excluded from the inventory. These habitats, because of their depth, go undetected by aerial imagery. By policy, the Service also excludes certain types of "farmed wetlands" as may be defined by the Food Security Act or that do not coincide with the Cowardin et al. definition. Contact the Service's Regional Wetland Coordinator for additional information on what types of farmed wetlands are included on wetland maps. This dataset should be used in conjunction with the Wetlands_Project_Metadata layer, which contains project specific wetlands mapping procedures and information on dates, scales and emulsion of imagery used to map the wetlands within specific project boundaries.

The principal focus of the wetland inventory is to produce wetland maps that are graphic representations of the type, size and location of wetlands in Wisconsin. Currently, there are two different datasets that have been created using different mapping methods and technologies.

The majority of the state was mapped using traditional stereo-pair, black-and-white, infrared photography. Within this context, the objective was to provide reconnaissance level information on the location, type, size of these habitats such that they are accurate at the nominal scale of the 1:20,000 (1 inch = 1667 feet) base map.

LiDAR Technology

LiDAR has advanced the ability to see and map wetland and surface water features.

New wetland mapping is underway in areas across the state at a nominal scale of 1:2000 (1 inch = 166.7 feet). The data are being mapped according to the National Wetland Inventory standards using new methods. Please see the WWI SOP for more information.

See LiDAR based status map for more information.

Data

The download contains both the older, high altitude, stereo-photo based mapping as well as the newer LiDAR based mapping. Any older WWI data within a new project area boundary have been removed.

The DNR recognizes the limitations of using remotely sensed information as the primary data source. They are to be used as a guide for planning purposes.

There is no attempt, in either the design or products of this inventory, to define the limits of jurisdiction of any federal, state, or local government or to establish the geographical scope of the regulatory programs of government agencies. Anyone intending to engage in activities involving modifications within or adjacent to wetland areas should seek the advice of appropriate federal, state, or local agencies concerning specified agency regulatory programs and jurisdictions that may affect such activities. The most accurate method of determining the legal extent of a wetland for federal or state regulations is a field delineation of the wetland boundary by a professional trained in wetland delineation techniques.

See https://dnr.wi.gov/topic/wetlands/inventory.html for more information on Wisconsin Wetland Inventory mapping.

Please contact Calvin Lawrence, GIS Specialist in the WDNR Waterway and Wetlands Section, at Calvin.Lawrence@wisconsin.gov.

The MassDEP Wetlands dataset comprises two ArcGIS geodatabase feature classes:The WETLANDSDEP_POLY layer contains polygon features delineating mapped wetland resource areas and attribute codes indicating wetland type.The WETLANDSDEP_ARC layer was generated from the polygon features and contains arc attribute coding based on the adjacent polygons as well as arcs defined as hydrologic connections.Together these statewide layers enhance and replace the original MassDEP wetlands layers, formerly known as DEP Wetlands (1:12,000). It should be noted that these layers provide a medium-scale representation of the wetland areas of the state and are for planning purposes only. Wetlands boundary determination for other purposes, such as the Wetlands Protection Act MA Act M.G.L. c. 131 or local bylaws must use the relevant procedures and criteria.The original MassDEP wetlands mapping project was based on the photo-interpretation of 1:12,000, stereo color-infrared (CIR) photography, captured between 1990 and 2000, and included field verification by the MassDEP Wetlands Conservancy Program (WCP). In 2007 the MassDEP WCP began a statewide effort to assess and where necessary update the original wetlands data. The MassDEP WCP used ESRI ArcGIS Desktop software, assisted by the PurVIEW Stereo Viewing extension, to evaluate and update the original wetlands features based on photo-interpretation of 0.5m, (1:5,000) digital stereo CIR imagery statewide, captured in April 2005. No field verification was conducted on this updated 2005 wetlands data.The 2005 WETLANDSDEP_POLY layer includes polygon features that distinguish it from its predecessor by overall changes in size and shape. In addition, new polygons have been created and original ones deleted. Many of the polygons, however, remain the same as in the original layer. All changes have been made according to the techniques described below. For the purpose of cartographic continuity, a small number of coastal polygons outside the state boundary where added based on data provided by the United States Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA).The 2005 WETLANDSDEP_ARC layer was generated to support map display and was designed to cartographically enhance the rendering of wetland features on a base map. Arc features in this layer were generated from the wetland polygons and coding (ARC_CODE) was assigned based on the adjacent polygon types. Hydrologic connection features (ARC_CODE = 7) were then added. Where delineated, these arc features indicate an observed hydrologic connection to or between wetland polygons. Although efforts were made to be comprehensive and thorough in mapping hydrologic connections, due to the limitations of aerial photo-interpretation some areas may have been missed.The types of updates made to the original wetland features include alteration, movement/realignment and reclassification. In some cases original wetland areas have been deleted and new areas have been added. Updates to original wetland features resulted from the following factors: changes in the natural environment due to human activity or natural causes; advances in the field of remote sensing, allowing for more refined mapping.Edit changes to the original wetland data include:Addition of new wetland and hydrologic connection featuresAppending (expansion or realignment) of existing (original) wetland and hydrologic connection featuresReclassification of wetlands features, due to change in wetlands environment from the original classificationMovement (or shifting) of original wetland features to better match the source imageryDeletion of original wetland or hydrologic connection features due to changes in wetlands environment or inconsistency with mapping criteria.Please note that although efforts were made to be comprehensive and thorough in the evaluation and mapping of statewide wetland resources some areas of the state may have been missed. Many of the wetland and hydrologic connection features remain the same as in the original data. The polygon attribute SOURCE_SCALE may be used to identify areas that have been altered from the original wetlands. The SOURCE_SCALE code 5000 indicates an updated wetland area. The SOURCE_SCALE code 12000 indicates an unaltered, original wetland polygon.

Digital wetlands data are intended for use with base maps and digital aerial photography at a scale of 1:12,000 or smaller. Due to the scale, the primary intended use is for regional and watershed data display and analysis, rather than specific project data analysis. The map products were neither designed nor intended to represent legal or regulatory products. Due to the quantity and complexity of the wetlands data the wetlands only display at 1:250,000 scale and greater. For wetland information visit: https://www.fws.gov/program/national-wetlands-inventoryView Dataset on the Gateway

In 2016 NYC Parks contracted with the UVM Spatial Analysis Lab to use modern remote sensing and object-based image analysis to create a new wetlands map for New York City. Data inputs include Light Detection and Ranging Data, State and Federal Wetland Inventories, soils, and field data. Because the map was conservative in its wetlands predictions, NYC Parks staff improved the map through a series of desktop and field verification efforts. From June to November 2020, NYC Parks staff field verified the majority of wetlands on NYC Parks' property. The map will be opportunistically updated depending on available field information and delineations. Another dedicated field verification effort has not been planned. As of June 2021, no subsequent updates to the data are scheduled. Original field names were updated to field names that are easier to understand. This dataset was developed to increase awareness regarding the location and extent of wetlands to promote restoration and conservation in New York City. This map does not supersede U.S. Fish and Wildlife Service National Wetlands Inventory (NWI) and New York State Department of Environmental Conservation (NYSDEC) wetlands maps and has no jurisdictional authority. It should be used alongside NWI and NYSDEC datasets as a resource for identifying likely locations of wetlands in New York City. Mapped features vary in the confidence of their verification status, ranging from "Unverified" (meaning the feature exists in its original remotely mapped form and has not been ground truthed) to "Verified - Wetland Delineation" (meaning the boundaries and type of wetland have been verified during an official wetland delineation). Because of the rapid nature of the protocol and the scale of data collection, this product is not a subsitute for on-site investigations and field delineations. The dataset also includes broad classifications for each wetland type, e.g. estuarine, emergent wetland, forested wetland, shrub/scrub wetland, or water. Cowardin classifcations were not used given rapid verfication methods. The accuracy of the wetlands map has improved over time as a result of the verification process. Fields were added over time as necessitated by the workflow and values were updated with information, either from the field verifications, delineation reports, or desktop analysis. OBJECTID, Shape, Class_Name_Final, Verification_Status, Create_Date, Last_Edited_Date, Verification_Status_Year, SHAPE_Length, SHAPE_Area https://www.nycgovparks.org/greening/natural-resources-group Data Dictionary: https://docs.google.com/spreadsheets/d/1a45qCho45MV-AuOlGxyaRp0cg3cRFKw4lAYBIaU3zi4/edit#gid=260500519 Map: https://data.cityofnewyork.us/dataset/NYC-Wetlands/7piy-bhr9

Indiana Wetlands from the USFWS NWI as of October 6, 2022 at https://www.fws.gov/node/264847

Download In State Plane Projection Here

The Lake County Wetland Inventory (LCWI) maps natural and artificial wetlands meeting definitions established by the federal agencies who work with the Lake County Geographic Information System staff to periodically review and update it. These agencies include the United States Environmental Protection Agency, the U.S. Fish and Wildlife Service, the USDA Natural Resources Conservation Service and the United States Army Corps of Engineers.

The 1989 federal wetland delineation standards for offsite wetland mapping are used. This data was last published in March of 1993. This update includes changes to the previous version of LCWI including: adjust current wetland boundaries to omit development, including roads; to fine tune boundary placement where that was intended by the original delineation, in some cases, adjust the wetland to photographic features / signature; delete wetlands which the committee decided were mapped in error - for example, trees which were mistaken for wet areas; create polygons for newly delineated artificial wetlands; and newly delineated wetlands or farmed wetlands caused by the continued deterioration of the agricultural drain tile system and increased runoff due to urbanization.

The LCWI is a useful tool for general planning and review purposes, but it does not take the place of an on-site delineation by a certified wetland specialist.

High resolution (1" = 100') orthorectified aerial imagery captured in April 2002 was used as the base for this update. Other data used as reference for this update include: 2004 SOIL SURVEY GEOGRAPHIC (SSURGO) DATABASE FOR LAKE COUNTY, IL - U.S. Department of Agriculture, Natural Resources Conservation Service; HYDROLOGY2002 - Lake County GIS/Map Division; 2' topography (CONTOURS) - Lake County GIS/Map Division; and various years of historical aerial photography for clarification. By using the more recent higher resolution photography, the resulting updated wetland boundaries are more accurate then the original boundaries published in 1993.

The State of Connecticut defines inland wetlands based on soils. The Connecticut Inland Wetlands and Watercourses Act defines wetland soils to include any of the soil types designated as poorly drained, very poorly drained, alluvial, or floodplain by the National Cooperative Soil Survey, as may be periodically amended, of the Natural Resources Conservation Service of the United States Department of Agriculture.Map units dominated by Connecticut inland wetland soils may have inclusions of non-wetland soils, and non-wetland map units may have inclusions of Connecticut inland wetland soils. On site investigation is necessary to determine the presence or absence of wetland soils in a particular area.This data set is a digital soil survey and generally is the mostdetailed level of soil geographic data developed by the NationalCooperative Soil Survey. The information was prepared by digitizingmaps, by compiling information onto a planimetric correct baseand digitizing, or by revising digitized maps using remotelysensed and other information.This data set consists of georeferenced digital map data andcomputerized attribute data. The map data are in a soil survey areaextent format and include a detailed, field verified inventoryof soils and miscellaneous areas that normally occur in a repeatablepattern on the landscape and that can be cartographically shown atthe scale mapped. The soil map units are linked to attributes in theNational Soil Information System relational database, which givesthe proportionate extent of the component soils and their properties.

This data layer is an element of the Oregon GIS Framework. The Oregon Wetlands Database (2019) is a geodatabase consisting of three feature classes: 1) Local Wetland Inventory (LWI) Wetlands, 2) National Wetland Inventory (NWI) Wetlands, and 3) More Oregon Wetlands (MOW). Each feature class contains polygons representing wetland boundaries. The three feature classes originated from different sources with distinct purposes, methodologies and time frames for generating geospatial wetlands data, and there is overlap among them; however, all are relevant to the conservation and management of wetlands across the state of Oregon. See the metadata of the individual feature classes for more background information and details per dataset.

The Informational Freshwater Wetland Mapping layer is only intended to be used for informational purposes in identifying the general location and extent of freshwater wetland areas of any size throughout the state. Informational Freshwater Wetland Mapping is not regulatory. The Freshwater Wetlands Act changed in 2022 such that wetlands greater than 12.4 acres in size are regulated regardless of their mapping status. In addition to larger wetlands, the Freshwater Wetlands Act regulates smaller wetlands of “unusual importance” if they meet one of eleven criteria described in the law and regulation. While maps contained on the Environmental Resource Mapper provide information on the potential locations of wetlands, the only definitive way to determine if a particular parcel or property contains regulated wetlands outside the Adirondack Park is to request a jurisdictional determination through DEC’s website (https://dec.ny.gov/nature/waterbodies/wetlands/freshwater-wetlands-program). The Freshwater Wetlands Act regulates most development activities located in the wetland or within a regulated “adjacent area.” This adjacent area is a minimum of 100 feet but may be extended for a limited number of particularly sensitive wetlands. Not all activities in and near wetlands are regulated. There are many exempt activities that landowners may undertake without permits. However, if you are not sure of which activities require permits near New York State regulated wetlands, please contact your regional DEC office.Wetlands are classified from Class I (which provide the most benefits) to Class IV (which provide fewer benefits). The classification is based on the work that wetlands do, such as storing flood water and providing wildlife habitat. The system for classifying wetlands is contained in regulation (6 NYCRR Part 664) and the classification of individual wetlands is determined as part of the jurisdictional determination process.For additional information on NYS Freshwater Wetlands, see DEC's website (https://dec.ny.gov/nature/waterbodies/wetlands/freshwater-wetlands-program).View Dataset on the GatewayFor information on wetlands inside the Adirondack Park, please contact the Adirondack Park Agency. For information on wetlands regulated under federal law, please contact the United State Army Corps of Engineers.Contact for this Data:DFW, Bureau of Ecosystem Health625 BroadwayAlbany, NY 12233Phone: 518-402-8920fw.ecohealth@dec.ny.gov

This data set is a Status Map that identifies the location of wetland data and no data areas. The wetland data itself represents the extent, approximate location and type of wetlands and deepwater habitats in the United States and its Trust Territories. These data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979). Certain wetland habitats may be excluded because of the limitations of aerial imagery as the primary data source used to detect wetlands. These habitats include seagrasses or submerged aquatic vegetation that are found in the intertidal and subtidal zones of estuaries and near shore coastal waters. Some deepwater reef communities (coral or tuberficid worm reefs) have also been excluded from the inventory. These habitats, because of their depth, go undetected by aerial imagery. By policy, the Service also excludes certain types of "farmed wetlands" as may be defined by the Food Security Act or that do not coincide with the Cowardin et al. definition.The U.S. Fish and Wildlife Service (Service) is the principal Federal agency that provides information to the public on the extent and status of the Nation's wetlands. The Service's strategic plan for our vast national wetland data holdings is focused on the development, updating, and dissemination of wetlands data and information to Service resource managers and the public. The development of the Wetlands Master Geodatabase is in direct response to the need to integrate digital map data with other resource information to produce timely and relevant management and decision support tools.For more information visit: https://www.fws.gov/wetlands/index.htmlView Wetlands Data on the Wetlands Mapper at: https://www.fws.gov/wetlands/Data/Mapper.htmlWetlands Web Services are available at: https://www.fws.gov/wetlands/Data/Web-Map-Services.htmlWetlands Data available as a KML at: https://www.fws.gov/wetlands/Data/Google-Earth.htmlWetlands Data Downloads available at: https://www.fws.gov/wetlands/Data/Data-Download.htmlWetland Data Standards available at: https://www.fws.gov/wetlands/Data/Data-Standards.html

This web mapping service is intended to provide information on Iowa's wetlands. In particular, data recorded in the National Wetland Inventory.

This data set represents the extent, approximate location and type of wetlands and deepwater habitats in Carteret County, NC, as of May, 2018. These data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979). The National Wetlands Inventory - Version 2, Surface Waters and Wetlands Inventory was derived by retaining the wetland and deepwater polygons that compose the NWI digital wetlands spatial data layer and reintroducing any linear wetland or surface water features that were orphaned from the original NWI hard copy maps by converting them to narrow polygonal features. Additionally, the data are supplemented with hydrography data, buffered to become polygonal features, as a secondary source for any single-line stream features not mapped by the NWI and to complete segmented connections. Wetland mapping conducted in WA, OR, CA, NV and ID after 2012 and most other projects mapped after 2015 were mapped to include all surface water features and are not derived data. The linear hydrography dataset used to derive Version 2 was the U.S. Geological Survey's National Hydrography Dataset (NHD). Specific information on the NHD version used to derive Version 2 and where Version 2 was mapped can be found in the 'comments' field of the Wetlands_Project_Metadata feature class. Certain wetland habitats are excluded from the National mapping program because of the limitations of aerial imagery as the primary data source used to detect wetlands. These habitats include seagrasses or submerged aquatic vegetation that are found in the intertidal and subtidal zones of estuaries and near shore coastal waters. Some deepwater reef communities (coral or tuberficid worm reefs) have also been excluded from the inventory. These habitats, because of their depth, go undetected by aerial imagery. By policy, the Service also excludes certain types of "farmed wetlands" as may be defined by the Food Security Act or that do not coincide with the Cowardin et al. definition. Contact the Service's Regional Wetland Coordinator for additional information on what types of farmed wetlands are included on wetland maps. This dataset should be used in conjunction with the Wetlands_Project_Metadata layer, which contains project specific wetlands mapping procedures and information on dates, scales and emulsion of imagery used to map the wetlands within specific project boundaries.

NWI digital data files are records of wetlands location and classification as defined by the U.S. Fish & Wildlife Service. This dataset is one of a series available in 7.5 minute by 7.5 minute blocks containing ground planimetric coordinates of wetlands point, line, and area features and wetlands attributes. When completed, the series will provide coverage for all of the contiguous United States, Hawaii, Alaska, and U.S. protectorates in the Pacific and Caribbean. The digital data as well as the hard copy maps that were used as the source for the digital data are produced and distributed by the U.S. Fish & Wildlife Service's National Wetlands Inventory project. The data provide consultants, planners, and resource managers with information on wetland location and type. The data were collected to meet U.S. Fish & Wildlife Service's mandate to map the wetland and deep-water habitats of the United States.The full Kansas geospatial catalog is administered by the Kansas Data Access & Support Center (DASC) and can be found at the following URL: https://hub.kansasgis.org/

The National Wetlands Inventory (NWI) dataset was downloaded from the US Fish and Wildlife Service website at https://www.fws.gov/wetlands/Data/State-Downloads.html on 05/04/2021. Metadata derives from original NWI database and updated to reflect the date of download. According to website, this layer was updated last October 1st, 2020. This is a clip of all wetlands features within the Westchester County boundary minus all riverines, Long Island Sound, and the Hudson River.This data set represents the extent, approximate location and type of wetlands and deepwater habitats in the United States and its Territories. These data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979). The National Wetlands Inventory - Version 2, Surface Waters and Wetlands Inventory was derived by retaining the wetland and deepwater polygons that compose the NWI digital wetlands spatial data layer and reintroducing any linear wetland or surface water features that were orphaned from the original NWI hard copy maps by converting them to narrow polygonal features. Additionally, the data are supplemented with hydrography data, buffered to become polygonal features, as a secondary source for any single-line stream features not mapped by the NWI and to complete segmented connections. Wetland mapping conducted in WA, OR, CA, NV and ID after 2012 and most other projects mapped after 2015 were mapped to include all surface water features and are not derived data. The linear hydrography dataset used to derive Version 2 was the U.S. Geological Survey's National Hydrography Dataset (NHD). Specific information on the NHD version used to derive Version 2 and where Version 2 was mapped can be found in the 'comments' field of the Wetlands_Project_Metadata feature class. Certain wetland habitats are excluded from the National mapping program because of the limitations of aerial imagery as the primary data source used to detect wetlands. These habitats include seagrasses or submerged aquatic vegetation that are found in the intertidal and subtidal zones of estuaries and near shore coastal waters. Some deepwater reef communities (coral or tuberficid worm reefs) have also been excluded from the inventory. These habitats, because of their depth, go undetected by aerial imagery. By policy, the Service also excludes certain types of "farmed wetlands" as may be defined by the Food Security Act or that do not coincide with the Cowardin et al. definition. Contact the Service's Regional Wetland Coordinator for additional information on what types of farmed wetlands are included on wetland maps. This dataset should be used in conjunction with the Wetlands_Project_Metadata layer, which contains project specific wetlands mapping procedures and information on dates, scales and emulsion of imagery used to map the wetlands within specific project boundaries.

Each wetland in the inventory is assigned a brief code ("NWI Code") to summarize its typology. A brief description is provided for each code ("NWI Description"). To get a full descriptive definition for any particular code, see the NWI Wetlands Code Interpreter: http://137.227.242.85/Data/interpreters/wetlands.aspx

For a detailed report on the data collection process, see: \Documents\WetlandsNWI\R03Y11P01.pdf

Many maps of open water and wetland have been developed based on three main methods: (i) compiling national/regional wetland surveys; (ii) identifying inundated areas by satellite imagery; (iii) delineating wetlands as shallow water table areas based on groundwater modelling. The resulting global wetland extents, however, vary from 3 to 21% of the land surface area, because of inconsistencies in wetland definitions and limitations in observation or modelling systems. To reconcile these differences, we propose composite wetland (CW) maps combining two classes of wetlands: (1) regularly flooded wetlands (RFW) which are obtained by overlapping selected open-water and inundation datasets; (2) groundwater-driven wetlands (GDW) derived from groundwater modelling (either direct or simplified using several variants of the topographic index). Wetlands are thus statically defined as areas with persistent near saturated soil because of regular flooding or shallow groundwater. To explore the uncertainty of the proposed data fusion, seven CW maps were generated at the 15 arc-sec resolution (ca 500 m at the Equator) using geographic information system (GIS) tools, by combining one RFW and different GDW maps. They correspond to contemporary potential wetlands, i.e. the expected wetlands assuming no human influence under the present climate. To validate the approach, these CW maps were compared to existing wetland datasets at the global and regional scales: the spatial patterns are decently captured, but the wetland extents are difficult to assess against the dispersion of the validation datasets. Compared to the only regional dataset encompassing both GDWs and RFWs, over France, the CW maps perform well and better than all other considered global wetland datasets. Two CW maps, showing the best overall match with the available evaluation datasets, are eventually selected. They give a global wetland extent of 27.5 and 29 million km², i.e. 21.1 and 21.6% of global land area, which is among the highest values in the literature, in line with recent estimates also recognizing the contribution of GDWs. This wetland class covers 15% of global land area, against 9.7% for RFWs (with an overlap ca 3.4 %), including wetlands under canopy/cloud cover leading to high wetland densities in the tropics, and small scattered wetlands, which cover less than 5% of land but are very important for hydrological and ecological functioning in temperate to arid areas. […]