The dataset is comprised of river conditions at La Grange, Peoria, Starved Rock, Marseilles, and Dresden Island Locks and Dams, along the Illinois River. Data were recorded bihourly from 1 Jan 1985 – 31 Dec 2016. For each location, pool elevation (ft), tailwater elevation (ft), head height (ft; calculated by the difference between pool elevation and tailwater elevation), discharge (cfs; when available) and total gate openness (sum of all open gates in ft), are given, where available. Open river conditions were calculated (0 = closed, 1 = open) for each two hour time period. Dam openness was assessed using the U.S. Army Corps of Engineers thresholds for open river conditions at each location.