Description: Display and define all surface waters identified within the 2020 305(b)/303(d) Water Quality Assessment Integrated Report. The Assessment Unit (AU) dataset was created from United States Geological Survey (USGS) National Hydrography Dataset (NHD) high-resolution 1:24,000 data extracted in September 2012. The NHD product was used by DEQ regional assessment staff to assign previously established assessment unit IDs based on predetermined up- and downstream extents and applicable Water Quality Standards. Some erroneous waters were removed and a few waters were corrected for spatial accuracy using Virginia Base Mapping Program aerial photography from Virginia Geographic Information Network (VGIN), and recent NHD data where available.There are 3 feature classes within the geodatabase:va_aus_estuarine – estuarine waters within the commonwealth, including the Chesapeake Bay and tidal tributaries to the Bayva_aus_reservoir – lakes and reservoirs with Water Quality Standards or those monitored within the commonwealth; see appendix 7 of the IR for a complete listva_aus_riverine – free flowing surface waters within the commonwealth This data constitutes the United States Environmental Protection Agency (EPA) approved version of the assessment unit hydrology for Virginia. Attributes assigned to each water segment are based on details associated with the ID305B (assessment unit ID) from the statewide water quality assessment database (ADB) (ADB is deprecated as of the 2020 cycle). Data validations are performed on the data prior to linking attributes to the GIS data, however errors may still occur.Additionally, a summary dataset of water quality monitoring stations (va_20ir_wqms) which includes DEQ and non-DEQ data is generated to supplement this AU data.Please direct any questions about attribute accuracy to the Data Contact.
Copyright Text: Virginia Department of Environmental Quality, Office of Ecology, Water Monitoring & Assessment Program
Description: Display and define all surface waters identified within the 2020 305(b)/303(d) Water Quality Assessment Integrated Report. The Assessment Unit (AU) dataset was created from United States Geological Survey (USGS) National Hydrography Dataset (NHD) high-resolution 1:24,000 data extracted in September 2012. The NHD product was used by DEQ regional assessment staff to assign previously established assessment unit IDs based on predetermined up- and downstream extents and applicable Water Quality Standards. Some erroneous waters were removed and a few waters were corrected for spatial accuracy using Virginia Base Mapping Program aerial photography from Virginia Geographic Information Network (VGIN), and recent NHD data where available.There are 3 feature classes within the geodatabase:va_aus_estuarine – estuarine waters within the commonwealth, including the Chesapeake Bay and tidal tributaries to the Bayva_aus_reservoir – lakes and reservoirs with Water Quality Standards or those monitored within the commonwealth; see appendix 7 of the IR for a complete listva_aus_riverine – free flowing surface waters within the commonwealth This data constitutes the United States Environmental Protection Agency (EPA) approved version of the assessment unit hydrology for Virginia. Attributes assigned to each water segment are based on details associated with the ID305B (assessment unit ID) from the statewide water quality assessment database (ADB) (ADB is deprecated as of the 2020 cycle). Data validations are performed on the data prior to linking attributes to the GIS data, however errors may still occur.Additionally, a summary dataset of water quality monitoring stations (va_20ir_wqms) which includes DEQ and non-DEQ data is generated to supplement this AU data.Please direct any questions about attribute accuracy to the Data Contact.
Copyright Text: Virginia Department of Environmental Quality, Office of Ecology, Water Monitoring & Assessment Program
Description: Display and define all surface waters identified within the 2020 305(b)/303(d) Water Quality Assessment Integrated Report. The Assessment Unit (AU) dataset was created from United States Geological Survey (USGS) National Hydrography Dataset (NHD) high-resolution 1:24,000 data extracted in September 2012. The NHD product was used by DEQ regional assessment staff to assign previously established assessment unit IDs based on predetermined up- and downstream extents and applicable Water Quality Standards. Some erroneous waters were removed and a few waters were corrected for spatial accuracy using Virginia Base Mapping Program aerial photography from Virginia Geographic Information Network (VGIN), and recent NHD data where available.There are 3 feature classes within the geodatabase:va_aus_estuarine – estuarine waters within the commonwealth, including the Chesapeake Bay and tidal tributaries to the Bayva_aus_reservoir – lakes and reservoirs with Water Quality Standards or those monitored within the commonwealth; see appendix 7 of the IR for a complete listva_aus_riverine – free flowing surface waters within the commonwealth This data constitutes the United States Environmental Protection Agency (EPA) approved version of the assessment unit hydrology for Virginia. Attributes assigned to each water segment are based on details associated with the ID305B (assessment unit ID) from the statewide water quality assessment database (ADB) (ADB is deprecated as of the 2020 cycle). Data validations are performed on the data prior to linking attributes to the GIS data, however errors may still occur.Additionally, a summary dataset of water quality monitoring stations (va_20ir_wqms) which includes DEQ and non-DEQ data is generated to supplement this AU data.Please direct any questions about attribute accuracy to the Data Contact.
Copyright Text: Virginia Department of Environmental Quality, Office of Ecology, Water Monitoring & Assessment Program
Description: This dataset contains the boundaries for lands of conservation and recreational interest in Virginia. The Conservation Lands Database is constantly being edited and updated. Historic easements are held by the Virginia Board of Historic Resources and administered by the Virginia department of Historic Resources. Data is released to the public quarterly and posted to the download section of the website: http://www.dcr.virginia.gov/natural_heritage/cldownload.shtml
Description: The TimeberHarvest feature class depicts the area planned and accomplished acres treated as a part of the Timber Harvest program of work, funded through the budget allocation process and reported through the Forest Service Activity Tracking System (FACTS) database within the Natural Resource Manager (NRM) suite of applications. Activities are self-reported by Forest Service Units.
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.
Name: 12-Digit Hydrologic Units with NLCD 2019 Summary
Display Field: NAME
Type: Feature Layer
Geometry Type: esriGeometryPolygon
Description: The Watershed Boundary Dataset (WBD) is a comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. It defines the areal extent of surface water drainage to a point except in coastal or lake front areas where there could be multiple outlets as stated by the "Federal Standards and Procedures for the National Watershed Boundary Dataset (WBD)" “Standard” (http://pubs.usgs.gov/tm/11/a3/). Watershed boundaries are determined solely upon science-based hydrologic principles, not favoring any administrative boundaries or special projects, nor particular program or agency. This dataset represents the hydrologic unit boundaries to the 12-digit (6th level) for the entire United States. Some areas may also include additional subdivisions representing the 14- and 16-digit hydrologic unit (HU). At a minimum, the HUs are delineated at 1:24,000-scale in the conterminous United States, 1:25,000-scale in Hawaii, Pacific basin and the Caribbean, and 1:63,360-scale in Alaska, meeting the National Map Accuracy Standards (NMAS). Higher resolution boundaries are being developed where partners and data exist and will be incorporated back into the WBD. WBD data are delivered as a dataset of polygons and corresponding lines that define the boundary of the polygon. WBD polygon attributes include hydrologic unit codes (HUC), size (in the form of acres and square kilometers), name, downstream hydrologic unit code, type of watershed, non-contributing areas, and flow modifications. The HUC describes where the unit is in the country and the level of the unit. WBD line attributes contain the highest level of hydrologic unit for each boundary, line source information and flow modifications.
Copyright Text: Funding for the Watershed Boundary Dataset (WBD) was provided by the USDA-NRCS, USGS and EPA along with other federal, state and local agenciesies. Representatives from many agencies contributed a substantial amount of time and salary towards quality review and updating of the dataset in order to meet the WBD Standards. Acknowledgment of the originating agencies would be appreciated in products derived from these data. See dataset specific metadata for further information
Description: The U.S. Geological Survey (USGS), in partnership with several federal agencies, has now developed and released seven National Land Cover Database (NLCD) products: NLCD 1992, 2001, 2006, 2011, 2016, 2019, and 2021. Beginning with the 2016 release, land cover products were created for two-to-three-year intervals between 2001 and the most recent year. These products provide spatially explicit and reliable information on the Nation’s land cover and land cover change. NLCD continues to provide innovative, consistent, and robust methodologies for production of a multi-temporal land cover and land cover change database. NLCD 2021 adds an additional year to the map products produced for NLCD 2019, with a streamlined compositing process for assembling and preprocessing Landsat imagery and geospatial ancillary datasets; a temporally, spectrally, and spatially integrated land cover change analysis strategy; a theme-based post-classification protocol for generating land cover and change products; a continuous fields biophysical parameters modeling method; and a scripted operational system. The overall accuracy of the 2019 Level I land cover was 91%. Results from this study confirm the robustness of this comprehensive and highly automated procedure for NLCD 2021 operational mapping (see https://doi.org/10.1080/15481603.2023.2181143 for the latest accuracy assessment publication). Questions about the NLCD 2021 land cover product can be directed to the NLCD 2021 land cover mapping team at USGS EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov. See included spatial metadata for more details.
Description: The U.S. Geological Survey (USGS), in partnership with several federal agencies, has now developed and released seven National Land Cover Database (NLCD) products: NLCD 1992, 2001, 2006, 2011, 2016, 2019, and 2021. Beginning with the 2016 release, land cover products were created for two-to-three-year intervals between 2001 and the most recent year. These products provide spatially explicit and reliable information on the Nation’s land cover and land cover change. NLCD continues to provide innovative, consistent, and robust methodologies for production of a multi-temporal land cover and land cover change database. NLCD 2021 adds an additional year to the map products produced for NLCD 2019, with a streamlined compositing process for assembling and preprocessing Landsat imagery and geospatial ancillary datasets; a temporally, spectrally, and spatially integrated land cover change analysis strategy; a theme-based post-classification protocol for generating land cover and change products; a continuous fields biophysical parameters modeling method; and a scripted operational system. The overall accuracy of the 2019 Level I land cover was 91%. Results from this study confirm the robustness of this comprehensive and highly automated procedure for NLCD 2021 operational mapping (see https://doi.org/10.1080/15481603.2023.2181143 for the latest accuracy assessment publication). Questions about the NLCD 2021 land cover product can be directed to the NLCD 2021 land cover mapping team at USGS EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov. See included spatial metadata for more details.
Description: The U.S. Geological Survey (USGS), in partnership with several federal agencies, has now developed and released seven National Land Cover Database (NLCD) products: NLCD 1992, 2001, 2006, 2011, 2016, 2019, and 2021. Beginning with the 2016 release, land cover products were created for two-to-three-year intervals between 2001 and the most recent year. These products provide spatially explicit and reliable information on the Nation’s land cover and land cover change. NLCD continues to provide innovative, consistent, and robust methodologies for production of a multi-temporal land cover and land cover change database. NLCD 2021 adds an additional year to the map products produced for NLCD 2019, with a streamlined compositing process for assembling and preprocessing Landsat imagery and geospatial ancillary datasets; a temporally, spectrally, and spatially integrated land cover change analysis strategy; a theme-based post-classification protocol for generating land cover and change products; a continuous fields biophysical parameters modeling method; and a scripted operational system. The overall accuracy of the 2019 Level I land cover was 91%. Results from this study confirm the robustness of this comprehensive and highly automated procedure for NLCD 2021 operational mapping (see https://doi.org/10.1080/15481603.2023.2181143 for the latest accuracy assessment publication). Questions about the NLCD 2021 land cover product can be directed to the NLCD 2021 land cover mapping team at USGS EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov. See included spatial metadata for more details.
Name: NHDPlus Catchments (downloaded June 2, 2023)
Display Field: DatasetName
Type: Feature Layer
Geometry Type: esriGeometryPolygon
Description: The High Resolution National Hydrography Dataset Plus (NHDPlus HR) is an integrated set of geospatial data layers, including the best available National Hydrography Dataset (NHD), the 10-meter 3D Elevation Program Digital Elevation Model (3DEP DEM), and the National Watershed Boundary Dataset (WBD). The NHDPlus HR combines the NHD, 3DEP DEMs, and WBD to create a stream network with linear referencing, feature naming, "value added attributes" (VAAs), elevation-derived catchments, and other features for hydrologic data analysis. The stream network with linear referencing is a system of data relationships applied to hydrographic systems so that one stream reach "flows" into another and "events" can be tied to and traced along the network. The VAAs provide capabilities for upstream and downstream navigation with linear referencing, analysis, and modeling. The elevation derived catchments are used to associate other landscape attributes, such as land cover, with stream segments