This data set includes riparian woody stem counts, stem densities and landscape variables collected at 28 sites along the South Platte River, Colorado, United States from 2011-2016. Riparian woody stem densities were collected in the field during 2011, 2015, and 2016, and include the species Ulmus pumila, Populus deltoides, Salix amygdaloides, Fraxinus pennsylvanica, and Elaeagnus angustifolia. For Ulmus pumila, data are included for total stem density and stem densities of three size classes: saplings, medium, and large trees. Landscape variables at each site include: farmstead density, population density, upland Ulmus pumila density, bridge density, road density, active river channel, floodplain area, upstream cumulative drainage area, and mean annual river flow.