VERBUND opens fish pass at the Inn power plant Braunau-Simbach
Next milestone reached in the restoration of consistency on the Inn: following a successful trial run, VERBUND opened the new fish pass for the cross-border Braunau-Simbach power plant on the Inn at a small ceremony on 23 September 2024. The VERBUND-Wasserkraft managing directors Michael Amerer and Karl Heinz Gruber welcomed, among others, the mayors of Kirchdorf, Johann Springer, Simbach, Klaus Schmid, and Braunau, Johannes Waidbacher. In a symbolic act, Kurt Vallée, the deputy district administrator of the district of Rottal-Inn, released a fish into the new 3.1 kilometre-long natural bypass river. VERBUND has invested 9.3 million euros here.
After almost a year of construction, the new fish pass enables all species of fish in the Inn to swim past the Braunau-Simbach power plant or to linger there for a while. The new bypass river means they can now reach the tributaries or floodplain waters again for the first time since the power plant was built. The bypass river also offers new habitats: wood, rocks and, in particular, gravel form typical river structures in the water and on the banks. The result is habitats for fish, birds, insects and amphibians.
A natural riverbank was created on the Inn downstream of the power plant in addition to the fish pass. Fish migration and habitat development are continuously documented by means of comprehensive scientific monitoring.
“The creation of new habitats in the area around our power plants is vital for improving the ecology of our waterways. The now completed bypass river here in Braunau-Simbach marks another milestone on the Inn. In the coming years, we will also remove the final obstacles along our hydropower plants on the Inn and Danube rivers with comprehensive ecological measures. From 2027, the river routes from the Iron Gate in Romania to Tyrol will be barrier-free for all migratory fish species,” says Michael Amerer, Managing Director of VERBUND-Wasserkraft.
The near-natural bypass river has a width of 5 to 8 metres and is designed to be like a natural river with seasonally varying flows of water. The flow rates vary between 2 and 8 m³/s and represent the natural drainage of a large tributary of the Inn. The high hydrological dynamic results in a constant reshaping of the riverbed and the banks, offering loose gravel habitats for spawning fish and gravel-breeding birds. All of the soil excavated within the construction site has been used to create new habitats.
Kurt Vallée, Deputy District Administrator of the district of Rottal-Inn: “Thanks to the good co-operation between all parties on both sides of the Inn, the redesign of the river bed and banks has ensured that the conditions for spawning fish and gravel-nesting birds are almost ideal. This new fish bypass has set a milestone – here, the focus was not only on talking about biodiversity, but on quickly implementing intelligent planning. I would like to express my thanks and appreciation for this.”
„Riverscape Lower Inn“
This important nature conservation project is part of the EU LIFE project “Riverscape Lower Inn”, which further promotes the natural development of the river landscape along the Lower Inn. It serves to achieve important goals of the Fauna Flora Habitat (FFH) and Bird Protection Directive within the scope of the European Natura 2000 network and the EU Water Framework Directive. In the coming years, VERBUND will implement numerous measures for the ecological development of the riverscape on the Lower Inn. In addition to the fish pass at Braunau-Simbach, the Life Project includes a near-natural bypass river at the Inn power plant Egglfing-Obernberg and the creation of aquatic habitats in the areas around the power plants at Egglfing-Obernberg and Schärding-Neuhaus. In addition, the dams of a total of four Inn power plants along a 40-kilometre stretch will be optimised and sustainably preserved as a habitat for protected plant and animal species through targeted maintenance measures.
Fish passes work
The fact that modern bypass rivers are accepted by fish is demonstrably shown by the comparable project “Consistency and habitat” at the Inn power plant Ering-Frauenstein. In the first year after initial operation in 2019, a total of around 40,000 fish migrated past the power plant. They belonged to 36 different fish species. The largest fish was a wels catfish with a body length of 1.2 metres. One of the highlights was the discovery of a number of specimens of the endangered Danubian longbarbel gudgeon.
VERBUND invests 400 million euros for land restoration, species protection and fish migration
“For the restoration of the waterways around all our hydropower plants, we will receive over 400 million euros from VERBUND by 2027. We have already invested around half of this amount, and the success of these measures can be demonstrated by extensive monitoring programmes practically from day one. Today, some 75% of the power plants are barrier-free again and 30% of the plant areas have been placed under nature conservation over time since the power plants were built. A further 100 million euros have already been approved or commissioned for the remaining power plants,” says VERBUND-Wasserkraft managing director Karl Heinz Gruber, giving an overview of the enormous volume being invested in the environment.
