Ownership: 100 %
Production: 2150 GWh
Power: 350 MW
The Røssåga power plants are located in Hemnes Municipality in Nordland County. Øvre Røssåga uses the height of fall between Lake Røssvatnet and Lake Stormyrbassenget, while Nedre Røssåga uses the height of fall between Lake Stormyrbassenget and the village of Korgen.
Lake Røssvatnet has a reservoir capacity of 2.35 billion cubic metres and is Norway's second largest lake, measured in surface area.
The development of the Røssåga power plants involves the municipalities of Hemnes, Hattfjelldal and Grane. The development, which occurred during the 1950s and 1960s, was linked to operating the ironworks in Mo i Rana, providing power for domestic supply to 19 municipalities in Midt-Helgeland, and electrification of the Nordland railway line. In the 1960s, Elkem's aluminium plant in Mosjoen arrived as a major consumer of power.
A major rehabilitation and upgrading programme has been done at the Røssåga power plants (October 2016) .
Refurbishment and expansion began in spring 2012 and is among the largest hydropower projects in Norway in the 2000s. Trial operation has been underway since late July to August.
The total capacity in Nedre Røssåga has increased from 250 MW to 350 MW. Total annual generation increases by approximately 200 GWh to about 2,150 GWh, equivalent to the consumption of more than 100,000 Norwegian households.
The project has a positive environmental impact. In parallel with the increased power generation, conditions has been improved for salmon and sea trout in Røssåga. Due to the project, water has now returned to a stretch of the river representing 30 percent of the spawning basis throughout the Røssåga river system.
The old power station consists of three existing units rehabilitated, while three units are decommissioned. At the same time a new power station has been built with one large unit. The new station is built inside the mountain, close to the the old one.
New waterways were partly driven by a tunnel boring machine for the first time in Norway in decades. In total, 19 km of new tunnels has been driven. At peak, 300 people have been working on the the plant.
Architect Hans Grinde drew the plans for and participated in the planning of both Røssåga power plants. Parts of Nedre Røssåga power plant will be preserved as they are, in accordance with a conservation plan drawn up by Statkraft in cooperation with the Norwegian Directorate for Cultural Heritage.