Michael Vlah , Spencer Rhea, Emily Bernhardt, Amanda DelVecchia, Nick Gubbins, Weston Slaughter, Audrey Thellman, Matthew R.V. Ross

The U.S. Federal Government supports hundreds of watershed ecosystem monitoring efforts from which solute fluxes can be calculated. While details of instrumentation and sampling methods vary across these studies, the types of data collected and the questions that motivate their analysis are remarkably similar. Nevertheless, little effort toward the compilation of these datasets has previously been made, and comparative watershed analyses have remained limited in scale. The MacroSheds project has developed a flexible, future-friendly system for continually harmonizing daily time series of streamflow, precipitation, and solute chemistry from 169+ watershed studies across the U.S., and supplementing each with a comprehensive set of predictive watershed attributes. The MacroSheds dataset is an unprecedented resource for watershed ecosystem science, and for hydrology, as a small-watershed supplement to existing collections of streamflow predictors, like CAMELS and GAGES-II. Macrosheds is accompanied by a web dashboard for visualization and an R package for local analysis.