Uvdal 1 Power Plant is located far into the mountainside south of the town of Uvdal

Construction of the power plant Uvdal 1 was begun in 1963 and it was commissioned in autumn 1966. The power plant is located 15 kilometres north of Rødberg in Buskerud county and uses water from the main reservoir Sønstevatn. The power plant utilises a 585-metre waterfall between Sønstevatn and the bottom of the valley in Uvdal.
The power station, which is located approx. 1,800 metres into the mountainside, contains two vertical Pelton generators with a total output of about 90 MW. The water flow through the plant is at a maximum of 18.5 cubic metres per second.
Normal annual production is 320 GWh.

Large reservoir in Sønstevatn

The main reservoir for Uvdal 1 is Sønstevatn in the Imingdalen valley, which is dammed up at a height of 1,060 metres above sea level. Originally, there were three lakes next to each other: Sjugurdstjern, Mevatn and Sønstevatn. The damming of these is from 8 to 31 metres. With a regulation height of 31 metres, the reservoir has space for an entire year’s drainage from the catchment area (approx. 220 million cubic metres). The Sønstevatn of today has entirely dammed up an area of approx. 13 square kilometres. The dam itself is approx. 320 metres long and is a rockfill dam with its maximum height at approx. 44 metres. Despite the fact that the dam is built partially from loose rock, it has proven to be a very stable construction.

The owners of Uvdal 1 Power Plant are Skagerak Kraft AS (90%) and E-Co Energi AS (10%).