epa.gov:93766FED-6DE0-4852-B880-4EFF6C93150F U.S. Environmental Protection Agency 20200608 20200608 vector digital data Washington, DC EPA Office of Water This dataset contains twelve-digit hydrologic subwatershed units aggregated from the NHDPlus v21+AK Beta State Catchment Fabric. These units express the Catchment Crosswalk logic used to assign NHDPlus catchments to HUC12 units and are not representative of the Watershed Boundary Dataset or other hydrologic unit systems. None None 20200608 publication date Complete Irregular -180.0 180.0 90.0 -90.0 ISO 19115 Topic Category environment boundaries geoscientificInformation inlandWaters EPA GIS Keyword Thesaurus Ecosystem Environment Estuary Ground Water Land Management Monitoring Natural Resources Regulatory Surface Water Water User keywords catchments watershed boundaries None United States None None. Please check sources, scale, accuracy, correctness and other available information. Please confirm that you are using the most recent copy of both data and metadata. U.S. Environmental Protection Agency mailing address

1200 Pennsylvania Avenue, NW MC 4503T

Washington DC 20460 999-999-9999 waters_support@epa.gov https://edg.epa.gov/EPA_Data_License.html No Confidentiality Standard Technical Controls Please refer to the source datasets for details on general accuracy. None None Please refer to the source datasets for more details on horizontal positional accuracy. Unknown U.S. Environmental Protection Agency (USEPA) and the U.S. Geological Survey (USGS) 2012 2.10 vector digital data Washington, DC U.S. Environmental Protection Agency https://www.epa.gov/waterdata/nhdplus-national-hydrography-dataset-plus online 2012 publication date NHDPlusV21 U.S. Geological Survey (USGS) 2019 Beta vector digital data Washington, DC U.S. Geological Survey (USGS) https://www.usgs.gov/core-science-systems/ngp/national-hydrography/nhdplus-high-resolution online 2019 publication date NHDPlusAKBeta Onshore catchments extracted from NHDPlus V2.1 NHDPlusV21 20200608 Onshore catchments extracted from NHDPlus AK Beta NHDPlusAKBeta 20200608 Datasets merged into national coverage 20200608 Datasets aggregated by HUC12 code per the NHDPlus v21 Catchment Crosswalk dataset. NHDPlusV21 20200608 Vector GT-polygon composed of chains 81368 WGS 1984 Web Mercator Auxiliary Sphere PROJCS["WGS_1984_Web_Mercator_Auxiliary_Sphere",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator_Auxiliary_Sphere"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],PARAMETER["Auxiliary_Sphere_Type",0.0],UNIT["Meter",1.0],AUTHORITY["EPSG",3857]] coordinate pair 0.0001 0.0001 meter D WGS 1984 WGS 1984 6378137.0 298.257223563 U.S. Environmental Protection Agency, Office of Water mailing address

1200 Pennsylvania Avenue, NW MC 4503T

Washington DC 20460 999-999-9999 waters_support@epa.gov Live Data and Maps Although these data have been processed successfully on a computer system at the Environmental Protection Agency, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. It is strongly recommended that careful attention be paid to the contents of the metadata file associated with these data to evaluate data set limitations, restrictions or intended use. The U.S. Environmental Protection Agency shall not be held liable for improper or incorrect use of the data described and/or contained herein. ArcGIS Server Map Service https://watersgeo.epa.gov/arcgis/rest/services/Support/CatchmentFabric/MapServer/0 None 20200608 20220608 U.S. Environmental Protection Agency, Office of Water mailing address

1200 Pennsylvania Avenue, N.W., Mail Code 4503T

Washington DC 20460 999-999-9999 waters_support@epa.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 local time