Wikipedia
Songdalselva (also known as Sogna / Sogne / Sygna / Søgneelva) is a river that originates in Finsland in Songdalen municipality, Vest-Agder, Norway. The catchment area is located between Otra's and Mandalselva's watersheds. The highest hills in the catchment area goes up to above sea level. Water flows are normally at its lowest in summer and highest in autumn and spring. There are only a few and small lakes in the river system. The steep slopes down from the moors can create short and intense flood rapids. The river flows through the valley Stallemodalen in Vennesla, and falls into Songdalen through a gorge at Underåsen. Here it receives more water from the right from the Gumpedalselva tributary. The river drops no more than about over the last to the river mouth, and has on this stretch a very meandering run. By Søgne Landbruksskole is a few meters high waterfall, Søgne waterfall. From the waterfall to the sea the river is called the Søgneelva. Songdalselva flows into the sea between Høllen and Åros in Høllefjorden in Søgne municipality.
It occurs both salmon and sea trout in the river. Fishing license is required.
In the post-war years up to the 1980's, the river was thought of as an open sewer. Bathing and fishing was not recommended. Water quality improved by the time the sewer was led through pipes and cleansed before discharged to the sea. Today's (2016) environmental issue is mainly illegal garbage disposal and plastic waste from farming, accumulation along the banks and flowing into the ocean when the river is flooding.
The watercourse was in 1993 protected against hydropower development pursuant to Norwegian law, by development plans through Conservation Plan IV for waterways.
mouth in Høllefjorden between Åros and Høllen. at the start of the gorge at Underåsen.