Ulla-Førre is Norway’s largest conglomeration of power plants and uses water from a catchment area spanning 2,000 square kilometres in Aust-Agder and Rogaland counties. Statkraft is the main regulator of the watercourse, and Skagerak Kraft owns 1.49 per cent of power production through its ownership in Otrakraft. Suldalsheiane, Bykleheiane and Lyseheiane make up most of the catchment area. It also covers Ulledalsåna, Førreåna and parts of Bratteliåna, which all flow into Suldalsvannet lake. Blåsjø lake is the main reservoir for the power plants and comprises 20 small and large dams in all and over 100 km of tunnels.

The four power plants and one pumping station that make up Ulla-Førre have an annual production corresponding to around 3.5 per cent of Norway’s energy consumption. The power complex is designed to utilise and even out variation in precipitation in that some of the power plants can be operated as pumping power plants that pump water back up to the reservoirs.

Most of the development of Ulla-Førre took place in the 1980s, despite the Norwegian parliament giving the go-ahead to purchase fall rights as early as 1912. The development also led to major infrastructure improvements, including a year-round connection to Eastern Norway on the northern side of Suldalsvannet lake. Significant amounts of water are released passed Hylen Power Plant in order to safeguard the salmon population in Suldalslågen river.

*The figures refer to plants where Skagerak Kraft holds an ownership interest.