Norway blew up a hydro dam to restore river health and free migratory routes for fish.
The 1916 built seven-metre high dam in the small town of Fåvang, in Innlandet, east Norway, has not been in use for more than 50 years.
The Tromsa River is a tributary of the Lågen River, which feeds into Lake Mjøsa, Norway’s biggest lake.
Campaigners say removing the dam will help fish in the area thrive again, including grayling, burbot, Alpine bullhead and common minnows.
It is hoped the main beneficiary will be the lake-dwelling trout, which can weigh more than 10kg and feeds in downstream lakes and the Lågen.
Until now, the fish have only been able to live and spawn in the lower 950 metres before the dam, whereas they will soon be able to swim 10km upriver.
The dam’s destruction is part of a trend to remove the obsolete barriers that litter Europe’s waterways. In October, the Open Rivers Programme, a €42.5 million project to provide grants to support the removal of small dams and the restoration of river flow across Europe.
Last month, the European Commission released a guide for member states to identify barriers that could be removed to help achieve the goal of restoring 25,000km of rivers to free-flowing by 2030.
It is estimated that there are at least 1.2 million instream barriers in Europe and that they are a factor in the massive drop in the number of migratory freshwater fish across the continent, with numbers declining by more than 90% between 1970 and 2016.