Example of fishways

We are currently processing on designing fishways and we are wondering what kind of fishway could be the most suitable to Aminnefors and Billnäs dams.

We really like the idea of a natural bypass fishway with a rockramp, in Billnäs but in Aminnefors, it might be better to design a fish ladder considering the dimensions of the dam and its location.

I have found some examples concerning fish ladders, there are four main types :
- pool-and-weir fishways
- vertical slot fishways
- denil fishways
- steeppass fishway

For more information, go to : http://www.michigan.gov/dnr/0,1607,7-153-10364_52259_19092-46291--,00.html

Basically :
-the first one is more suitable for trouts and salmons but not for species that don't jump, so for small fishes it will be difficult. It can be sensitive to floods.

Pool-and-weir fishway : Columbia River-USA

-the second one has a constant flow pattern which means mainly that it won't be sensitive to water elevation in the river. It is effective for a wide variety of species, as long as the speed in the baffle is not too fast.

Vertical slot fishway : Murray River-Australia

-the third one has a wide range of water speed, so here again many species can use this fishway. It can also handle a wide range of changes in the upstream water surface elevation.

Denil Fishway at Trout Creek Dam- Michigan

Denil fish ladder : Blackfoot River Watershed-Montana

-the last one uses the same principle as the denil fishway but uses many baffles. Here again, a wide range of species can pass through this fishway. Same remark for the water elevation. This fishway is made of metal, and the sections are narrower than the denil fishway.

Steeppass fishway in Alaska

Another examples I have found is one small fish ladder near Otterton on the River Otter in Devon, England, United Kingdom and one fish ladder in Uppsala in Sweden.

Now we have to choose...

-Caroline