VERBUND Hydro Power submitted official documents in mid-May to the relevant authorities for a fish pass at the Aschach run-of-river hydropower plant on the Danube in Upper Austria.
The project is part of the EU-backed LIFE Blue Belt Danube Inn programme and is intended to restore fish migration continuity along the Upper Austrian Danube. VERBUND said the project would make the river fully passable to fish from the Bavarian border for the first time.
“With the fish pass in Aschach, we are filling a last major void on the Upper Austrian Danube and creating consistent migration routes for numerous fish species,” said Christian Freiler, head of the Upper Danube plant groups at VERBUND.
The scheme includes a 1.8km fish passage system designed to overcome a 15m impoundment height at the hydropower plant. The design combines several passage elements, including approximately 765m of vertical slot fishways, a 450m rectangular channel, a 285m asymmetric fish ladder and a 303m semi-natural bypass stream.
According to VERBUND, the bypass channel must be largely engineered because of site space constraints.
VERBUND Project Manager Hannes Einbild said: “The combination of the vertical slot fishway, fish ladder and near-natural bypass stream makes it possible to overcome the extraordinary water level efficiently and in a manner appropriate for the fish. A particular challenge was the large amount of compensation water of up to 8m3/sec required during planning, as it was almost impossible to adapt the flow in the fish pass to the needs of the fish.”
The company said the project is intended to reconnect spawning and nursery habitats along the Danube corridor and improve conditions for gravel- and flow-dependent fish species.
LIFE Blue Belt Danube Inn is focused on improving ecological connectivity and habitat conditions in Natura 2000 sites along the Danube and Inn rivers through habitat restoration and creation measures.
