Northeast Hydrologic Unit Code 6 Watersheds, modified

This dataset defines the boundaries of 40 large watersheds in the Northeast, modified slightly from the Watershed Boundary Dataset (WBD)  developed by the U.S. Geological Survey. The WBD depicts a hierarchical, multi­level drainage system composed of drainage areas called “hydrologic units.” Hydrologic Unit Code (HUC) 6 drainage areas represent the third level of classification in the system (from largest to smallest area). The modifications for this project consisted of combining several drainage areas with a relatively small area in the Northeast, such as those on the periphery of the region. (An example is the Southeastern Lake Ontario and the Oswego drainage areas.) These watershed boundaries were used to stratify the Aquatic Core Network, the Terrestrial Ecosystem­-based Selection Index and the Landscape Capability models so that the aquatic and terrestrial core areas represented the highest values of ecosystem and species habitat in each of the watersheds.