During 1990 and 1991, a series of research flows were released from Glen Canyon Dam. Data collected at the streamflow-gaging station on the Colorado River above National Canyon near Supai from that period have been compiled and entered into the U.S. Geological Survey database. The data consist of measurements of suspended-sediment concentration and sand sizes in suspension, sand sizes of streambed sediment, and velocity of the Colorado River above National Canyon near Supai streamflow-gaging site. Velocity and sediment data are available upon request from the Arizona Water Science Center and from the U.S. Geological Survey water-quality database (http://waterdata.usgs.gov/az/nwis/qw).