Illspitz Kleine Ill – construction of an innovative tributary

Simultaneously with the execution of the new power plant Illspitz, a tributary of the storage capacity had to to be built. Main focus is a design that suits environmentally and nature-friendly as much as possible the existing main riverbed. Although the newly created bypass water course is an inevitable intervention in nature, it should be designed as gently as possible for the flora and fauna. The new stream bed was aligned parallel to the ponded areas but outside the flood protection dams. It was designed to match with the bottom slopes and flow conditions corresponding to the natural, undisturbed river Ill.

The furnishing and structuring within the riparian forest allows the settlement and recovery of the newly created territory by formerly native fish and plants. The peculiarity lies in the fact that the tributary represents not only upstream fish migration facility, a size-wise shrunk habitat of the Ill with all its natural capabilities. Monitoring 12 months after commissioning confirmed the return of different species of fish to the “Kleine Ill”. Thus, the bypass water course is an innovative, essential, ecological component of the hydro project “Power Plant Illspitz”.