The Iller has a catchment area of 2,152 square kilometres (831 sq mi). It ranks as the seventh of Bavaria's rivers by water flow, with an average throughput of 75 cubic metres per second (2,600 cu ft/s) at Senden, a short distance upstream from the Danube. The power of the river is used for the production of hydroelectricity via eight power stations with a total net capacity of 51 MW (1998).