This USGS data release includes a comma separated value (CSV) file that contains 19 reach-based dam metrics representing stream fragmentation and flow alteration for nearly 2.3 million stream reaches in the conterminous United States. Dam metrics fall into three main categories: count and density, distance-based, and cumulative reservoir storage (described below). These data were developed using spatially verified large dam locations (n=49,140) primarily from the National Anthropogenic Barrier Dataset (NABD) 2012 that were spatially linked to the National Hydrography Dataset Plus version 2.1 (NHDPlusV2.1). These dam metrics have been summarized using the unique identifier field native to the NHDPlusV2.1 (COMID) which can be used to join this table to spatial layers and data tables of the NHDPlusV2.1. Non-fluvial features representing lakes and reservoirs in the NHDPlusV2.1 are included (~300,000 features), however coastlines are excluded. For more details see the associated publication: 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 https://doi.org/10.1016/j.scitotenv.2017.02.067