Description: 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.
Description: The municipal separate storm sewer system (MS4) receiving waters are hydrologically connected waterways that receive stormwater discharges from the City's MS4. Whether a waterway is considered a MS4 receiving water is determined by the feature's characteristics, such as size and presence of flow, its presence in the National Hydrologic Dataset (NHD), and its connection to other receiving waters. The MS4 receiving waters can be used for a range of tasks required for the City's MS4 permit, including the delineation of the MS4 service area, identification of MS4 outfalls, selection of dry weather screening sites, and other elements. MS4 receiving waters ARE NOT intended to be used as regulatory "waters of the U.S."This dataset was developed from the 2017 planimetric data of water surfaces (PLAN_Hydro_Surfaces) from the City of Virginia Beach, wetland extents from the National Wetland Inventory (NWI), ditch and canal information from the City of Virginia Beach, and data from the National Hydrologic Dataset (downloaded in March 2017). The dataset of waterbodies was developed by removing areas from the PLAN_Hydro_Surfaces dataset with a feature code (FCODE) corresponding to wetlands, bay, or ocean. From the NWI dataset, a definition query was used to select only Estuarine and Marine Wetlands, Freshwater Emergent Wetlands, and Freshwater Forested/Shrub Wetlands. Once the definition queries were established, the water surfaces and wetland features were merged. The initial line dataset was developed from NHD flowlines (canal/ditch, coastline, connector, and stream/river), the City's ditch file (roadside ditches and privately-owned ditches were removed), a line created based on aerial image, or the stormwater culverts. The initial line dataset was compared with GIS data of the City's stormwater infrastructure and site plans to assess the hydrologic connectivity of various segments with downstream waterways. The initial line dataset has been buffered at distance of 2ft on each side of the lines creating a 4ft wide polygon representing those lines.The MS4 receiving waters will be updated regularly as additional data is known.
Copyright Text: Source datasets were acquired from the City of Virginia Beach, the United States Geological Survey, and the US Fish and Wildlife Service. The initial MS4 receiving waters were delineated by Brown and Caldwell.