Each hydropower plant on the Inn comprises:
- the machinery hall with the turbines,
- the weir systems for flood release,
- the dams and dikes for the accompanying flood protection
- and – if inland drainage has been disrupted by the dams – the pumping stations and ditches, which guarantee agricultural use that existed before construction of the barrage.
The VERBUND hydropower plants on the Inn are therefore not only plants for generating electricity but also improve flood protection in the region. VERBUND also focuses on improving the ecological conditions at individual sites and on restoring natural river landscapes. We implement a large number of measures in this regard, such as:
- creating continuity of flow with fish bypasses,
- giving structure to bodies of water,
- connecting tributaries.
In order to guarantee habitats for fish with all their habitat requirements – from spawn to adult specimens – management of the gravel banks is additionally carried out in the near-natural fish bypass or below the weir. Another important component for the long-term conservation of fish fauna is the maintenance of sediment continuity through sediment management, a topic of the EU Water Framework Directive (WFD) for species conservation in man-made rivers.
Fish bypass at the Rosenheim power plant:
The fish bypass is currently being planned and suitable construction variants are being examined. Implementation is planned for 2019-2020.
Numerous structural measures at the Rosenheim site were developed and implemented in intensive coordination talks with the responsible authorities and the local fishermen’s associations. Due to its straightened banks, the Inn was severely impaired as a habitat for fish throughout the area of the dam. The removal of the straightened bank line and the creation of structures similar to the old course of the river have restored habitats, especially for juvenile fish habitats and other animal and plant species. The calm shallow water zones represent high-quality habitats and can be used by many fish inhabiting the Inn as flood and winter shelters. Newly created dry sites near the dyke can be colonised by species whose natural habitats are the gravel banks of former river arms. With the stone blocks of the rigid bank protection, new structures are to be created which, in addition to providing protection against erosion will also assume ecological functions, e.g. as reptile habitats.