Changes in anthropogenic influences on streams and rivers in the conterminous U.S. over the last 40 years, derived for 16 data themes

This product consists of time-series calculations of anthropogenic characteristics derived for 16 data themes for multiple scales covering the conterminous United States. The characteristics are those which (a) have consistent data sources, and (b) have the potential to affect the water quality of streams and rivers. All 16 data themes are provided for Hydrologic Unit Code level-10 (HUC-10) boundaries (n = 15,458). Additionally, measures of land use and imperviousness are provided for U.S. Environmental Protection Agency (USEPA) Level 4 ecoregions (n = 967) and for U.S. counties (n = 3,109). The data may be scaled up to broader areas; that is, HUC-10 data may be scaled up to HUC-8, 6, 4, or HUC-2 areas, Level 4 ecoregions may be scaled [...]