This dataset contains a summary of the characteristics of near-surface flow reversals at the Electrical Dispersal Barrier System (EDBS) on the Chicago Sanitary and Ship Canal at Romeoville, Illinois during Water Year 2018 (October 1, 2017, to September 30, 2018). Water velocity near the water surface is measured on a five-minute sampling interval in the EDBS using surface velocity radar at nine measurement cells on a cross section near U.S. Geological Survey streamgage 05536995 (Chicago Sanitary and Ship Canal at Romeoville, Illinois). Flow reversal events are analyzed for each individual cell as well as for the average velocity over all nine cells. For the analysis of individual cells, a flow reversal event is defined as a period of time in which the velocity in an individual cell is negative (flowing upstream). For the analysis of the average velocity, a flow reversal event is defined as a period of time in which the average velocity over all nine cells is negative (flowing upstream). Velocity observations and statistics for each flow reversal event are provided in Comma Separated Values (CSV) files stored in a zipped folder named 05536995-WY2018-Flow-Reversal-Events.zip.