These data layers represent hydrography for Rock County, Wisconsin in 2015. It is a feature class within the geodatabase, “Rock_Hydro_2015.gdb”. The feature layers included in the geodatabase are “Rock_HydroPoly_2015” and “Rock_HydroLine_2015”.HydroPoly: [This is an ESRI Feature Class of the Hydrology polygons in Rock County, Wisconsin. This dataset is being used as a base for the Rock County Hydrography re-delineation project.The methodology used to construct this feature class used numerous datasets as reference and verification of active hydrography within Rock County. The datasets used were: USGS 7.5 Topo Quad Digital Raster Grids, 2004 and 2005 NAIP Aerial Photography, 2005 and 2006 Pictometry Oblique and Top-down Orthophotography, March of 2000 Orthophotography, March of 2000 Digital Terrain Models, March of 2000 2 Foot Contour Topography. The primary data layer of reference was the USGS 7.5 Topo Quad Digital Raster Grids for Rock County. The attribute field 'Pres_USGS' refers to the presence of the hydrology depicted on the USGS maps. As many of these maps were created decades ago, secondary and tertiary reference and verification of the extent and delineation of the hydrography was done using other current orthophotography and digital data such as terrain modeling, and 2-foot contour topography. In some cases, the extents, delineation, and configuration of the hydrography was adjusted to current (2006-2007) conditions based on this newer, more accurate data.]HydroLine: [This is an ESRI Feature Class of the Hydrology 'line work' in Rock County, Wisconsin. This dataset is being used as a base for the Rock County Hydrography re-delineation project.The methodology used to construct this feature class used numerous datasets as reference and verification of active hydrography within Rock County. The datasets used were: USGS 7.5 Topo Quad Digital Raster Grids, 2004 and 2005 NAIP Aerial Photography, 2005 and 2006 Pictometry Oblique and Top-down Orthophotography, March of 2000 Orthophotography, March of 2000 Digital Terrain Models, March of 2000 2 Foot Contour Topography. The primary data layer of reference was the USGS 7.5 Topo Quad Digital Raster Grids for Rock County. The attribute field 'Pres_USGS' refers to the presence of the hydrology depicted on the USGS maps. As many of these maps were created decades ago, secondary and tertiary reference and verification of the extent and delineation of the hydrography was done using other current orthophotography and digital data such as terrain modeling, and 2-foot contour topography. In some cases, the extents, delineation, and configuration of the hydrography was adjusted to current (2006-2007) conditions based on this newer, more accurate data.]