E2NHDPlusV2_us: Database of Ancillary Hydrologic Attributes and Modified Routing for NHDPlus Version 2.1 Flowlines

The National Hydrography Dataset Plus, Version 2 (NHDPlusV2) is an attribute rich, digital hydrologic network for the Conterminous U.S. developed by the U.S. Environmental Protection Agency (EPA) and U.S. Geological Survey (USGS). SPAtially Referenced Regressions On Watershed attributes (SPARROW), is a process-based/statistical model that relies on a digital hydrologic network, like NHDPlusV2, in order to establish spatial relations between monitored contaminant loads, contaminant sources, and other watershed characteristics. The USGS National Water Quality Assessment (NAWQA) project adopted the medium-resolution NHDPlusV2 network as the primary framework supporting SPARROW modeling, and has become a unifying system for reporting hydrologic information. This metadata describes enhancements made to improve the routing capabilities and ancillary hydrologic attributes of NHDPlusV2 to support modeling and other hydrologic analyses. The resulting enhanced network is named E2NHDPlusV2_us.