Sjønstå River

Sjønstå River
The Sjønstå River in low-flow conditions. Picture taken below the hill Stokkviknakken
Location in Nordland county
Native name	Sjønståelva
Other name(s)	Langvasselva
Country	Norway
Physical characteristics
Main source	Langvann Valley
River mouth	Øvervatnet 67°12′21″N 15°42′53″E / 67.20583°N 15.71472°E / 67.20583; 15.71472Coordinates: 67°12′21″N 15°42′53″E / 67.20583°N 15.71472°E / 67.20583; 15.71472
Length	12.7 km (7.9 mi)
Discharge	Average rate: 32.8 m3/s (1,160 cu ft/s)

The Sjønstå River (Norwegian: Sjønståelva, known as the Langvasselva in its upper course) is a river in the municipality of Fauske in Nordland county, Norway.

The Sjønstå River is the main river of the Sulitjelma drainage system. The stretch from its source at Langvatnet (Long Lake) to the village of Sjønstå, where it empties into Øvervatnet (Upper Lake) has been developed into the Sjønstå Hydroelectric Power Station. The river has many small tributaries.Norwegian County Road 830 runs parallel to the Sjønstå River. The Sulitjelma Line formerly ran along the river. The drainage system is regulated by many hydroelectric stations. The river is 12.7 kilometers (7.9 mi) long and has a drainage basin of 779.45 square kilometers (300.95 sq mi). The river's average discharge is 32.8 cubic meters per second (1,160 cu ft/s).

The river gently flows from Langvatnet, but it has some rapids. The only waterfall is located at contour level 60 m (200 ft), where the river runs through narrow sections with steep hillsides. The river has been seriously affected by pollution. After the Sjønstå power plant was built, large quantities of water flowed from Langvatnet down to Øvervatnet, and this has led to less pollution. The lower part of the river supports salmon and has a permanent population of trout.

There are several hydroelectric power stations on the river operated by Salten Kraftsamband:

In 2013, a concession was requested from the Norwegian Water Resources and Energy Directorate to build the Sjønstå Falls Hydroelectric Power Station. It is planned to have an intake at 58.4 meters (192 ft) at the existing threshold in the river. The installed capacity will be about 2.7 MW. According to the plan, the average annual production will be 7.3 GWh. The development will create a further reduction in water flow on a 1,370-meter (4,490 ft) stretch of the Sjønstå River. The planned release from the plant is a minimum of 600 liters per second (21 cu ft/s) in the summer season and 150 liters per second (5.3 cu ft/s) in the winter season.