Thanks to modern fish migration aids, power plants are no longer insurmountable barriers for fish and other aquatic life. This allows them to continue their migration past the power plant. VERBUND's comprehensive habitat approach with near-natural bypass waters also makes it possible to create new habitats for many species.
The Braunau-Simbach power plant is a run-of-river power plant on the Inn and located in the municipalities of Ranshofen (Upper Austria) and Kirchdorf am Inn (Bavaria). The power plant was built between 1951 and 1954. Today, four vertical Kaplan turbines generate an average of about 550 GWh of electricity annually.
A new dynamically doted bypass was constructed from 2023 to 2024 to ensure passability. On the one hand, it establishes passability and also creates new watercourse habitat. The large natural bypass river was created from a study of variants and designed in accordance with German and Austrian guidelines so that the entire fish fauna (all species and all life stages) can swim past the power plant without restriction.
It also provides reproduction areas and juvenile fish habitats for the river fish fauna. In addition to the fish fauna, other animal groups such as gravel-breeding birds also benefit from the newly created gravel banks.
The large near-natural bypass river has a total length of 3.1 km and a width of between 5 and 8 metres. It is also designed with a variety of depths. The discharge varies seasonally between 2 and 8 m³/s and is similar to the natural discharge of a large tributary of the Inn. The highly dynamic nature of the river leads to a constant reshaping of the river bed and banks, creating loose gravel habitats for spawning fish and gravel-breeding birds.
The construction work was designed to be environmentally and climate-friendly. The excavated soil (totalling 110,000 m³) was used within the construction site to create new habitats. This minimised transport routes and vehicle emissions, which benefited the climate, the residents of the surrounding communities and the wildlife.
The Egglfing-Obernberg hydropower plant is a run-of-river power plant on the Inn in the municipalities of Bad Füssing (Bavaria) and Obernberg (Upper Austria). It was put into operation in 1944.
In the course of the Malchinger Bach, which runs along the left bank of the Inn and flows into the Inn downstream of the power plant, VERBUND is constructing an approximately 5.8 km long and 15 to 20 m wide, dynamically endowed bypass.
It is designed with a varied depth distribution and offers several different habitat types. The flow varies seasonally between 4 and 40 m³/s and thus mimics the natural flow of a large tributary of the Inn. The high hydrological dynamics lead to a constant remodelling of the river bed and banks, providing loose gravel habitats for spawning fish and gravel-breeding birds.
The bypass channel covers a total of around 10.6 metres in height and is divided into two sections. The connecting channel with a length of 1.7 kilometres is the link from the reservoir water level in the headwater to the lower floodplain level. The eyelet channel continues at the level of the floodplain in the original valley gradient of the Inn until it flows into the tailwater of the power station. This measure is currently at the authorisation stage.
Lost river structures should be recreated around a total of three power plants in the project area. The floodplains play a special role in this – as habitats for typical flora and fauna.
Embankments in the area of the power plants are not just side effects of hydropower. They are also habitats of special quality – assuming appropriate care is taken. The opportunity to develop species-rich meadows and drygrass areas of European importance should be taken at a total of four power plants.
