The Pennsylvania State UniversityThe Erie PA Watershed mapping will consist of the following hydrological units i.e. watersheds and subwatersheds covering river systems draining large hydrologic unit regions, all attributed by a standard nomenclature. A hydrologic unit is a drainage area delineated to nest in a multi-level, hierarchical drainage system. Its boundaries are defined by hydrographic and topographic criteria that delineate an area of land upstream from a specific point on a river, stream or similar surface waters. A hydrologic unit can accept surface water directly from upstream drainage areas, and indirectly from associated surface areas such as remnant, non-contributing, and diversions to form a drainage area with single or multiple outlet points. Hydrologic units are only synonymous with classic watersheds when their boundaries include all the source area contributing surface water to a single defined outlet point. This dataset has gone through extensive quality review process to ensure accuracy and compliance to the Federal Standard for Delineation of Hydrologic Unit Boundaries (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/water/watersheds/?cid=nrcs143_021630)FileengPennsylvania Spatial Data Access (PASDA)PublicErie PA Watersheds - major subsheds [Pennsylvania]DatasetsPennsylvania