ArcelorMittal sheet piles support salmon migration along the Rhine

12 June 2025

The usefulness of steel sheet piles is widely recognised, whether they are used in foundations, retaining walls or harbour walls, or to secure riverbanks during flooding or protect coasts from tides. However, it is less well known that they can also play a crucial role in the construction of fish passes, which are essential for reintroducing migratory fish into some rivers. The Rhine is one such river, and with its high flow rate, it has a unique ecosystem that requires restoration and preservation.

The Rhinau and Marckolsheim fish pass project

Electricité De France (EDF) has been awarded the contract to construct fish passes at hydroelectric plants at Rhinau and Marckolsheim near Strasbourg as part of the France Relance programme, funded by both France and the European Union.

On each side of a power station, upstream and downstream of the river, the fish passes will facilitate crossing a 13-metre elevation over nearly a kilometre. This involves creating 90 upstream pools, each separated by 20cm drops, which are perfectly suited for fish migration. The project for both passes is expected to take five years to complete and will employ up to 150 people.

To date, the latest fish pass involving ArcelorMittal steel is at the Marckolsheim hydroelectric plant, which is nearing completion.

The objective of this initiative is to enable the return of Atlantic salmon to Basel in Switzerland, from where they have been absent since the 1950s due to various developments such as canal and dam construction along the Rhine. Also, a large chemical spill polluted the river in 1986 and decimated the fish population. Major projects since then have aimed to restore the river’s ecosystem and bring the Atlantic salmon back to Basel, where it used to be a symbol of the town a long time ago.

A passage between the river and the sea for salmon

The Rhine is a wide river with a substantial flow, and its power stations are spaced along its 1,230km length. One might assume that salmon could thrive between two stretches of river, but this is not the case. The Atlantic salmon, like other species, is a migratory fish that requires access to different environments throughout its life cycle.

In winter, salmon reproduce in freshwater rivers and streams. This is where females lay their eggs, males fertilise them, and the fry are born. After spending one or two years in the river, the smolts are strong enough to migrate to the sea in the spring. They remain in the ocean for two or three winters, and once they reach adulthood, they return to their natal watercourses to reproduce. Few adult salmon are strong enough to return to the sea after spawning, but all of them will attempt the journey if the passage is open. 

This entire cycle depends on the passage from a river to the sea and back. We are proud to contribute to this process with our sheet piles, which are helping to restore and preserve ecosystems.