A river meanders through meadows and small shrubs near the Ottenheim-Wilhering power station.

Ecological
measures

We are improving fish passability at the run-of-river power plants on the Danube with a variety of ecological measures: Together for a diverse and interconnected Danube.

Fish passability is to be established through the construction of new bypass arms. In addition to creating fish passability, the bypass arms will also provide new habitats. All implementations will be carried out in compliance with the current guidelines (FAH guidelines of the Federal Ministry) and will be evaluated by scientific studies such as fish ecological monitoring.

2015 to 2016

Europe's longest fish migration aid: Ottensheim-Wilhering

A 14.2 km long bypass arm is being built over the Innbach-Aschach channel with a seasonally-adapted water allocation by the Danube and the natural discharge dynamics of the tributaries. This bypass channel best meets the high ecological and technical requirements for fish passability. In addition, the near-natural design of the structure with depressions (pools), fords and bays creates additional habitats for fish and other animals.

The bypass arm itself is not located in a Natura 2000 area, but represents an important link between the Natura 2000 areas on the Danube and their tributaries. In addition to connecting these areas, important stepping stone biotopes are created, which significantly support the exchange between the populations in the protected areas.

The inflow structure is located on the right bank of the Danube at the root of the Ottensheim-Wilhering power station at river km 2158.4. To ensure that the water flow corresponds to the ecological conditions, it is equipped with a dotation structure with closable flaps. The bypass arm integrates sections of the Brandstätter Arm, the Aschach detour channel and the Innbach. Together with the Abwinden-Asten power plant's "Stauwurzel power station side arm" module, this is a unique habitat network of this size and quality for the Danube in Austria.

The picture shows part of the Ottensheim Wilhering fish migration aid after completion. Bushes and trees line the watercourse.

2016 to 2017

Fish migration aid at the Greifenstein power station

The new fish migration aid runs independently of the famous "watering course" in the Greifensteiner Au. The design of the entrance is particularly challenging, as the guiding current has to be sufficient to guide the fish at different water levels.

The 4.4-kilometre-long bypass stream overcomes the difference in level at the Greifenstein power station and also provides habitat and spawning grounds for the Danube's flagship fish species. The attractive design includes shallow and deep sections, gravel banks and predatory trees to create space for the greatest possible diversity of species.

The fish migration aid near Greifenstein winds its way through flora and fauna. Here you can see a river loop in the greenery.

2019 to 2020

Gravel banks for the Melk dam root

The successful LIFE+ Danube-Ybbs connectivity project is to be continued with new gravel banks at the so-called Ybbser Scheibe in the reservoir root of the Melk power plant.

In the bank area of the Ybbser Scheibe between river km 2057.70 and 2054.90, structuring of the bank zone was carried out using gravel fill. A sequence of gravel banks and gravel islands was created, resulting in current-calmed zones as well as gravel areas with shallow overflow at low and medium water levels.

The main objective of this measure is to improve the living conditions and spawning areas for fish species that depend on gravel and gravel banks, such as barbel, nase, zingel and streber. Gravel is removed from the main bed of the Danube near the mouth of the Erlauf and placed along the left bank of the Danube near Hagsdorf according to a detailed plan. 

In winter 2019/2020, work on the bank structures of the Danube in the Ybbser Scheibe area was completed. A total of 225,000 m³ of gravel was relocated within the Danube. The banks not only provide a new habitat for fish, but are also very popular with bathers. 

A view of the Ybbser Scheibe from above. The new gravel banks, which are intended to provide a new habitat for fish in particular, are clearly visible.

2019 to 2020

Fish migration aid Danube power station Abwinden-Asten

As part of the LIFE Danube Network, the Abwinden-Asten power plant on the Danube was upgraded with a modern fish migration aid. The fish migration aid was completed in 2020.

A fish migration aid is being retrofitted on the right bank. The fish ladder is designed as a near-natural bypass arm. With the exception of the lowest section, it is located in the "TRAUN-DONAU-AUEN" FFH and bird sanctuary. The stream will bridge a total height difference of 9.3 m (at normal water flow) between the reservoir and the tailwater.

In accordance with the international state of the art, the entrance is located downstream of the turbine outlets. This ensures that the fish migration aid is easy to find, especially for the spawning migrations of the Danube's main current-loving fish species (nase, barbel and huchen)

Over a distance of more than 5 kilometers, fish and other creatures will find a new habitat and an opportunity to pass the power plant. In total, around five hectares of new water habitat will be created. The total investment in this measure amounts to around EUR 6.5 million, which is being funded not only by VERBUND but also by the European Union, the Federal Ministry for Sustainability and Tourism, the state of Upper Austria and the Upper Austrian State Fishing Association.

View of the Abwinden Asten power station. On the left you can see part of the riverbank. The blue sky is reflected in the Danube.

2019

Bank structuring in the Abwinden-Asten reservoir area

A new tributary and an island will be created at the root of the dam at the Abwinden-Asten Danube power plant (at the mouth of the Ottensheim-Wilhering power plant bypass arm). The approx. 500 m long side arm of the Danube (river km 2146.4 to 2145.9) lies entirely on the power plant site between the mouth of the Innbach stream and the Danube and will provide fish and other aquatic animals with habitats protected from wave action, shallow water zones, dynamic rearrangements, etc., thus significantly improving the quality of the habitat compared to the current state of the bank. Bank protection is not required in the new side arm.

The flow velocities will be well above 0.5 m/s even at low water, and the flow rate at mean water will be over 100 m³/s. The gravel produced during construction (approx. 300,000 m³) will largely be used for structuring measures in the reservoir root area and for redesigning the estuary areas of the left-bank tributaries Pesenbach and Große Rodl.

The picture shows a pond at the construction site of the Abwinden-Asten power station against a bright blue sky.

2019

Bank structuring in the Abwinden-Asten reservoir area

A new tributary and an island will be created at the root of the dam at the Abwinden-Asten Danube power plant (at the mouth of the Ottensheim-Wilhering power plant bypass arm). The approx. 500 m long side arm of the Danube (river km 2146.4 to 2145.9) lies entirely on the power plant site between the mouth of the Innbach stream and the Danube and will provide fish and other aquatic animals with habitats protected from wave action, shallow water zones, dynamic rearrangements, etc., thus significantly improving the quality of the habitat compared to the current state of the bank. Bank protection is not required in the new side arm.

The flow velocities will be well above 0.5 m/s even at low water, and the flow rate at mean water will be over 100 m³/s. The gravel produced during construction (approx. 300,000 m³) will largely be used for structuring measures in the reservoir root area and for redesigning the estuary areas of the left-bank tributaries Pesenbach and Große Rodl.

Bank at Abwinden-Asten: The bank is lined with various large trees and you can already see the first traces of the construction site on the left-hand side.
Foto: Lorem ipsum / VERBUND

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