Building fish ladders at hydropower stations

Migrating fish like salmon and sea trout face challenges in passing through hydropower stations, impacting their ability to reach spawning areas.

Fish ladders have been constructed at several hydropower stations, including Stornorrfors (Ume River), Hietamankoski, and Leuhunkoski (Kymmene River), to enable passage capacity for migrating fish.

In 2025, over 10,000 salmons and 400 sea trouts passed through the Stornorrfors fish ladder on their way to spawning areas in the river Vindelälven. Additional measures have been taken to facilitate fish migration in the old riverbed downstream of the hydropower plant.

The 300-meter-long ladder was put into operation in 2010. Vattenfall is, in collaboration with the Swedish University of Agricultural Sciences (SLU), also analyses how the downstream passage of salmon and troult kelts through Stornorrfors can be improved.

In Finland, Vattenfall is planning to build a fishway together with the Finnish state at a dam that is jointly owned and operated. The dam divides the flow between the artificial Lake Hirvijärvi, where Vattenfall owns a hydropower plant, and the original stream that bypasses the lake. A constant flow is already maintained in the original stream, but the fishway will enable migration of local fish populations. The project is currently in the design phase and does not yet have a permit.