Velocity and water-quality surveys were completed along an approximately 71-mile reach of the Ohio River between Markland Locks and Dam (river mile 531.5) and McAlpine Locks and Dam (river mile 606.8) on October 27–November 4, 2016 (survey #1), and June 26–29, 2017 (survey #2). Water-quality data collected in this reach included surface measurements and vertical profiles of water temperature, specific conductance, pH, dissolved oxygen, turbidity, chlorophyll, and phycocyanin. Streamflow and velocity data were collected simultaneous to the water-quality data at cross-sections and along longitudinal lines (corresponding to the water-quality surface measurements) and at selected stationary locations (corresponding to the water-quality vertical profiles). All velocity and water-quality data were georeferenced with a differential GPS receiver with submeter accuracy. The data were collected to understand variability of flow and water-quality conditions relative to simulated reaches of the Ohio River and to aid in identifying parts of the reach that may provide conditions favorable to spawning and recruitment habitat for Asian carp.