Reported are a series of river velocity measurements taken one diameter upstream of a 25 kW vertical axis river kinetic turbine deployed in the Winnipeg River at Pointe du Bois, located 150 km northeast of Winnipeg. A load-bank located on the river shore provides a resistive load for the turbine generator. An acoustic Doppler velocimeter measures velocity fluctuations at a sample rate of 200 Hz. Analysis of acoustics Doppler velocimeter data measured upstream of the turbine quantifies the variation in the mean and fluctuating components of river flow velocity. Results show that in this particular test site the river contains eddies with the same order of magnitude as the turbine diameter or greater. Measurements upstream of the operating turbine indicate reduction in the mean velocity with eddies breaking down into smaller sizes. These smaller eddies increase the turbulence intensity of the incoming flow and increase the high frequencies energy level in the power spectra. (C) 2012 Elsevier Ltd. All rights reserved.