This CSV file contains 21 dam metrics representing stream fragmentation and flow alteration for nearly 2.3 million stream reaches in the conterminous USA. Dam metrics fall into four main categories: segment-based, count and density, distance-based, and cumulative reservoir storage (described below). These data were developed using spatially verified large dam locations (n=49,468) primarily from the National Anthropogenic Barrier Dataset (NABD) that were spatially linked to the National Hydrography Dataset Plus version 1 (NHDPlusV1). These dam metrics have been summarized using the unique identifier field native to the NHDPlusV1 (COMID) which can be used to join this table to spatial layers and data tables of the NHDPlusV1. Non-fluvial features in the NHDPlusV1 (lake and reservoir flow paths, coastlines, etc.) are excluded (see NFHP metadata). Please contact Arthur Cooper (coopera@msu.edu) for a copy of the publication associated with this data: Cooper, A.R., Infante, D.M., Daniel, W.M., Wehrly, K.E., Wang, L., Brenden, T.O. 2017. Assessment of dam effects for streams and fish assemblages of the conterminous USA. Science of the Total Environment doi:10.1016/j.scitotenv.2017.02.067

This tabular data set represents base flow index (BFI) compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data is the "Base-flow index grid for the conterminous United States" produced by the United States Geological Survey (Wolock, 2003). Units are percent. Base flow is the component of streamflow that can be attributed to ground-water discharge into streams. The BFI is the ratio of base flow to total flow, expressed as a percentage. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).