Longitudinal Hydrophone Profile Data on the Upper Colorado River, Colorado, June 6 to 8, 2019

In 2019, the U.S. Geological Survey, in cooperation with the Upper Colorado River Wild and Scenic Stakeholder Group, studied the magnitude and recurrence interval of streamflow needed to initiate bed movement of gravel-sized and finer sediment in a segment of the Colorado River in Colorado to better understand sediment movement and its relation to flow regimes of the river. Bed movement occurred more frequently and at lower streamflows from State Bridge to Catamount Bridge compared to the study area upstream from State Bridge. Two longitudinal hydrophone profiles were carried out at different streamflows to collect underwater acoustic data using hydrophones throughout the study area on June 6-8, 2019 (June 6-8 longitudinal profile) and June 18-19, 2019. The June 6-8 longitudinal profile began at the Pumphouse Recreation Area and ended at the Dotsero boat launch located at Dotsero, Colo. For the June 6-8 longitudinal profile, one of the mobile hydrophone systems, consisting of two H2a-XLR hydrophones (Aquarian Audio, 2013) and a recording system, was attached to a 16-foot Hyside inflatable raft and mounted about 1 foot below the water line (one on the port side of the raft and the second on the starboard side of the raft). A second mobile hydrophone system, consisting of one H2a-XLR hydrophone (Aquarian Audio, 2013) and a recording system, was attached to a 16-foot Down River Equipment inflatable cataraft and mounted about 1 foot below the water line on the stern of the raft.