The National Electric Power Works (RARIK) were licensed by law to build a 2,000 Hp power plant on River Grimsa or River Fjardara in 1952.  According to these plans, the towns Seydisfiord, Neskaupsstadur, and Eskifiord were to reap the advantages.  After extensive research, the authorities decided on a 2,4 MW power station on River Grimsa, below the Grimsarfoss Waterfall (18 m).

River Grimsa is a run off river with its sources in the mountains between the Eastfiords and the Fljotsdalur Area.  It spills into River Lagarfljot at Vallanes.  The name Grimsa only applies to a part oft the river, which has several other names further upriver from the confluence of rivers Mulaa and Geitdalsa.  Its total catchment area is about 500 km².  The water volume is very fluctuating, at the most 300 m³/sec, which is ten times the average flow.  The minimum flow is about 1 m³/sec.

The construction work started in the summer of 1955.  Because of local conditions, an underground power house was the best solution.  Artificial rapids were created about 35 m above the edge of the waterfall and just above it a 400 m long dam was constructed, 12 m high at its highest point.

A Francis generator with a vertical axis was installed.  The power station is two storeys high, both under and above ground.  The generators are underground and above it is the control centre, and a workshop.  A 30 m long discharge tunnel was excavated to a gorge below the waterfall.  The power plant was inaugurated on June 15^th 1958 and the work was finished at the end of November.

Shortage and disruptions of the water flow have been problems from the beginning, especially during winter, mainly because of the limited size of the reservoir.  The utilization of the available water supplies has, however, been favourable, between 5,000 and 7,000 hours annually.
Picture:  Rafteikning.