• Slowly rotating screws with soft protective edging on the screw helix
  • No fine grates
  • Small distance between the screw and trough to prevent fish from being caught
  • Structuring of the bank zones around the weir and fish ladder with gravel areas and dead wood shoring
  • Habitat for mayflies, snails and caddis flies retained 

Hydropower screws are fish friendly

Our hydropower screws are not fast rotating turbines and therefore do not pose a hazard to migratory fish. 

Hydropower screws use a special method: If a fish swims into the hydropower screw in the headwater, it gradually turns with it, moving downwards before swimming out on its way downstream. This is less of a shock to the fish, than it is for us to slide down a flume. Many, very many studies have clearly demonstrated that this does not harm the fish.

No fine grates required
Our robust technology only makes use of a coarse grate with a distance greater than 10 cm. This allows leaves, stones and branches to continue on their way. Unlike with fine grates, there is as little intervention as possible in the composition of the debris.

Protection of the waterside areas is important
Fish specialists and conservationists also recognise that today, agricultural land often stretches right up to the water's edge. Substantial amounts of fertilisers and the removal of alluvial forest along the course of a river have a considerable influence on the number of fish. Where there are no trees to shade the water, it becomes too warm for the fish. When constructing a new weir or better yet, renewing and upgrading an existing weir system, aspects of the bank structure will be taken into account.

When constructing facilities to aid the upstream migration of fish, specialist planners also ensure that it is always possible to recreate structures typical for the body of water in question, such as pebble banks and sandbanks. Of course, this is time-consuming, but it all helps the system become part of the unspoilt natural environment.

Case studies

  • Hydropower screw CR, Bischofsmais - Germany
  • Hydropower screw SH, Hausen - Germany
  • Hydropower screw BS, Eidenberg - Austria