Blåsjø is the tenth largest lake in Norway by area. It is located in the municipality of Bykle

Bykle

Bykle is a municipality in Aust-Agder county, Norway. It is located in the traditional region of Setesdal. The administrative center is the village of Bykle in the southern part of the municipality. Another village nearby is Nordbygdi...

 in Aust-Agder

Aust-Agder

is a county in Norway, bordering Telemark, Rogaland, and Vest-Agder. In 2002, there were 102,945 inhabitants, which is 2.2% of the total population in Norway. Its area is . The administrative center of the county is in Arendal....

 county

Counties of Norway

Norway is divided into 19 administrative regions, called counties . The counties form the primary first-level subdivisions of Norway and are further divided into 430 municipalities...

 and the municipalities of Hjelmeland

Hjelmeland

is a municipality in Rogaland county, Norway. Hjelmeland was established as a municipality on 1 January 1838 . Two other municipalities were later separated from it: Årdal and Fister , but these were both again merged with Hjelmeland on 1 January 1965.Hjelmeland is known for their fruit and fish...

 and Suldal

Suldal

Suldal is a municipality in the northeast of Rogaland county, Norway located in the Ryfylke historically traditional district. Sand i Ryfylke is a the administrative center of Suldal....

 in Rogaland

Rogaland

is a county in Western Norway, bordering Hordaland, Telemark, Aust-Agder and Vest-Agder. It is the center of the Norwegian petroleum industry, and as a result of this, Rogaland has the lowest unemployment rate of any county in Norway, 1.1%...

 county. The lake is about 20 kilometres (12.4 mi) west of the village of Bykle. It has a surface area of 84.48 square kilometres (32.6 sq mi). It lies 1055 metres (3,461.3 ft) above sea level and has a shoreline of about 200 kilometres (124.3 mi).

Blåsjø was formed by building a series of dams on several small lakes and it functions as a reservoir

Reservoir

A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...

 for the Ulla-Førre

Ulla-Førre

Ulla-Førre is a hydropower complex in Suldal, Hjelmeland and Bykle in Norway. It has an installed effect of approximately 2100 MW, and the annual average production is 4,45 TWh . The complex includes the artificial lake Blåsjø, which is made by dams around 1000 meters above the sea level...

 hydroelectric power

Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

station. The lake has an annual energy generation potential of about 7.8 TWh.