Portimokoski Fishway Opens 970 km on the Tornio River

On the afternoon of Thursday 27 August 2026, on the bank of the Tengeliönjoki in Ylitornio,

the King of Sweden tipped the first trout out of a bag into water that no fish from the sea

had reached in about a hundred years. Carl XVI Gustaf, Finland’s Minister of Agriculture and

Forestry Sari Essayah and Minister of Climate and the Environment Sari Multala were there to

inaugurate the Portimokoski fishway: the second of two bypasses around the dams of a

hydropower plant, and the piece that reconnects a major tributary of the Tornio River, and the

lake district behind it, with the Gulf of Bothnia.

The number the Lapland ELY Centre attaches to it is 970 kilometres of river and lake system

opened to migratory fish, “nearly a thousand kilometres” in the official wording. For a

border river whose main stem already runs free from the fells to the sea, that is the largest

single change in decades. Here is what was built, what the first summer’s cameras actually

recorded, and what it means if you fish, or want to.

What opened: two fishways around the Portimokoski power plant on the

Tengeliönjoki in Ylitornio, Finnish Lapland. The lower one, a natural bypass channel at

Haapakoski (about 85 m long, 4 m of rise), was finished in December 2024. The upper one at

Portimokoski (about 175 m, 5.5 m of rise) was completed on 31 October 2025 and inaugurated

Closed since: the 1920s, when the first Haapakoski power plant went up. The

current Portimokoski plant dates from 1987 (10.5 MW, 16.5 m head).

Cost and funding: about two million euros, paid from the EU’s TRIWA LIFE

programme and Finland’s national NOUSU programme for migratory fish.

First summer on camera: over 3,000 fish recorded passing

through between June and August 2026, mostly roach, dace, ide and bream, plus pike and

perch. No salmon, trout or whitefish yet.

Released on the day: 2,820 second-summer salmon juveniles of Tornionjoki

stock and 20 adult sea trout, donated by a local fish farm.

The Tornionjoki, with the Muonionjoki above it, is the border between Finland and Sweden, and

it is one of the very few large rivers in Europe with no dam on its main channel. Its wild

salmon are counted by sonar at Kattilakoski every summer. In 2026 the count reached 36,829 by

3 July, against 11,000 to 18,000 at the same point in each of the three previous years, a

recovery the Natural Resources Institute Finland (Luke) attributes to strong numbers of

salmon that spent two winters at sea, fish of four to eight kilos.

The catch has always been the tributaries. The Tengeliönjoki flows out of Lake Miekojärvi,

the lake where you can officially step over the Arctic Circle, and reaches the Tornionjoki

below Aavasaksa. According to Pohjolan Voima, whose subsidiary co-owned the plant, the dams

on the Tengeliönjoki were the only significant migration barrier in the whole Tornionjoki

system. Behind them sits a lake district: Portimojärvi, Miekojärvi, Vietonen, Raanujärvi, and

the streams between them. Sea trout and whitefish used to run it, and according to the ELY

Centre so did salmon, until the first Haapakoski power plant cut the route in the 1920s.

Two obstacles remain higher up. The Kaaranneskoski and Jolmankoski plants still block the

branches above Miekojärvi towards Vietonen and Raanujärvi, the local fisheries area notes, so