20230915 13074100 1.0 TRUE Sub Watersheds 12Digit The Sub Watershed data set contains areas of land that contribute runoff and groundwater into a specific stream system. Each feature in this data set represents the drainage basin for a single named stream or waterbody.  The drainage basins were delineated from Baltimore County's 1953 topographic maps at 1:2400 scale.  Stream names were extensively researched by S. Hank Grose.  Stream name sources included 1970-1990 state highway maps and various historic maps.