This line shapefile contains contours that were derived from a mosiac of 10 meter digital elevation models for the extent of the Russian River basin, located in Sonoma and Mendocino Counties, California. This layer can be used for watershed analysis and planning in the Russian River region of California. Circuit Rider Productions and National Oceanic and Atmospheric Administration (2002) 10 Meter Contours: Russian River Basin, California. Circuit Rider Productions. The 7.5-minute digital elevation model (DEM) data are digital representations of cartographic information in a raster form. The DEMs consist of an array of elevations for ground positions at regularly spaced intervals. The data are produced in 7.5- by 7.5-minute blocks from either digitized cartographic map contour overlays of a scanned National Aerial Photography Program (NAPP) photographs. The DEM data are stored as profiles with a 10- or 30-meter square grid spacing along and between each profile. Approximate file sizes are 9.9 megabytes for a 10-meter resolution and 1.1 megabytes for a 30-meter horizontal resolution. Data profiles for this product do not always have the same number of elevations because of the variable angle between true north and grid north in the Universal Transverse Mercator (UTM)
projection coordinate system. The DEM data for 7.5-minute units correspond to the USGS 7.5-minute topographic quadrangle map series for all of the United States and its territories except Alaska. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.