Landsvirkjun generates electricity from renewable, natural resources but the infrastructure required to generate energy causes unavoidable disturbance to the environment. The construction of power stations, transport of water and necessary manmade structures can have an effect on the ecosystem and the natural environment. Landsvirkjun operates 16 power stations in five areas of operation, all around the country. The Company carries out extensive monitoring and detailed research within the areas affected by its operations. The objective is to assess if and how operations affect the environment and to find solutions to reduce any effects.

The most extensive monitoring is carried out on freshwater ecology and birdlife alongside reindeer monitoring. The research is carried out in cooperation with the various universities, research institutes and independent specialists.

Freshwater ecology monitoring

Landsvirkjun extensively monitors river biota in lakes, reservoirs and rivers in the affected areas of all its power stations. The objective is to monitor any changes to the biota, in particular fish stocks. Extensive monitoring can facilitate the timely implementation of mitigation measures to reduce any environmental impact.

In 2013, seven reports were released on freshwater ecology; four on the affected areas of the Fljótsdalur Hydropower Station, two on Þjórsá and Tungnaá catchment areas (the Þjórsá area) and one on Sog (the Sog area) catchment area.


The affected area of the Fljótsdalur Hydropower Station

There are two large glacial rivers (Jökulsá á Dal and Lagarfljót), that feed into the Héraðsflói area and both of these originate from the Vatnajökull Glacier. By harnessing the Jökulsá á Dal River, most of the water accumulates in the Hálslón River. The water is then channelled into a headrace tunnel and into the Jökulsá í Fljótsdal River and subsequently flows out to the sea, via Lagarfljót.

The environmental impact assessment for the Kárahnjúkar Hydropower Project showed that water transport would have a significant effect on both Lagarfljót and Jökulsá á Dal as well as other rivers within the catchment area. These effects are now mostly becoming clear. The water has become more transparent in Jökulsá á Dal and primary production has increased. However, turbidity and discharge have increased in Lagarfljót. Water transparency, a key factor in primary production in a fresh-water ecosystem, is therefore less.


Fljótsdalur Hydropower Station and main rivers


Lagarfljót before utilisation

Glacial sediment and frequent changes to water levels are the main characteristics of Lagarfljót. The suspended sediment limits the light from penetrating the water and this means that primary production is bound to the upper layers of the water and coastline. Investigations on the amount of phytoplankton and zooplankton, in the last few decades, revealed no significant changes. However there is insubstantial data on invertebrate and algae species in Lagarfljót before the area was harnessed.

In 2013, a report was released on diatoms (bacillariophyceae) and invertebrates in Lagarfljót (2006-2007). The report outlined previous research carried out before water transport began in the Fljótsdalur Hydropower Station catchment area. The main results were as follows:

  • The secchi disk depth (a measure of the transparency of the water) was approx. 20–60 cm in the summer of 2006 and approx. 20–30 cm during the same period in 2007.
  • The quantity of zoo plankton was less than the quantity generally found in other large lakes in Iceland. The density of terrestrial invertebrates on stones was above average.
  • Research showed that variability in the composition of diatoms each time is mostly dictated by water surface fluctuations at the low-water mark (24%) and the turbidity or quantity of suspended stream load (10%). Variability is less affected by other variants such as conductivity and water temperature. 

An analysis of measurements data from monitoring at Lagarfljót in 2011 and 2012 will be completed this year. The results will be used to compare the status of the area now and before the catchment area was harnessed.


Fish in Lagarfljót

The discharge in Lagarfljót increased considerably when Jökulsá á Dal was harnessed. Water particle transit time, in Lagarfljót, is now approx. 6 months rather than one year and seasonal fluctuations in the water flow has levelled off. The secchi depth in Lagarfljót has decreased as predicted. The secchi depth in the summer of 2012 was approx. 13-15 cm but was 20-60 cm before harnessing.

In 2013, a report was released by the Institute of Freshwater Fisheries on Brown trout and Arctic char in the Lagarfljót area in 2011 and 2012. The report also covers research on juveniles in the tributaries of the Lagarfljót and Jökla, Fögruhlíðará and Gilsá rivers in 2012. The main results were as follows:

  • The decrease in Arctic char numbers has been continuous and began before the Fljótsdalur Hydropower Station began operations. The Brown trout population is more stable and there are no indications of a decline in numbers.
  • The size of fish in Lagarfljót has decreased and they are not as well nourished. The true effects of the power stations will become clearer in the next few years. This could be due to the fact that the fish caught up until now are mainly fish that hatched before the area was harnessed. Future research will focus on the state of the fish stock that has hatched and reached adulthood after harnessing began in Lagarfljót.
  • The food source available to the Arctic char and the Brown trout has changed. Terrestrial food sources have, to some degree, taken over aquatic food sources which could be a consequence of less production in Lagarfljót.

Fish migration can be affected by manmade structures such as dams and the outflow of hydropower stations. Changes of food availability and changes of food source can also affect the ability of fish to adapt to a changing habitat.

In 2013, a report was released on research conducted in 2010 and 2011 on the migration patterns of salmon and sea trout in Lagarfljót. The main results were as follows:

  • Sea trout continues to spawn in Lagarfljót’s tributaries but salmon does not seem to migrate further upstream than the rapids at the Lagarfoss Waterfall. It is therefore clear that the Lagarfljót tributaries are important for sea trout in the area.
  • Salmon harvest figures have decreased below Lagarfoss in the past few years. Various mitigation measures to increase fish migration are being considered.

Turbidity from headrace tunnels

Research has been conducted on the biota in the Glúmstaðadalsá and Hrafnkelsá rivers since 2010. The objective is to assess the effects of turbidity from a leak originating from the headrace tunnels at Hálslón in the Glúmstaðadalsá and Hrafnkelsá rivers. The leak becomes apparent when the reservoir water level reaches 610-615 metres above sea level (the highest level being 625 MASL) but rapidly decreases when the water surface level drops below 620 metres. A report containing measurements from 2012 was released in 2013. The main results were as follows:

  • Turbidity levels were higher in the Glúmstaðadalsá and Hrafnkelsá rivers in 2012 and 2010 than in 2011. This is due to the higher water level in Hálslón.
  • Turbidity increases throughout the summer. Turbidity measurements are at their highest point during Hálslón’s annual spillover period (at the end of the summer) but decrease again towards the end of the autumn period.
  • It is difficult to assess the impact of turbidity on benthic communities in Glúmsstaðadalsá and Hrafnkelsá. The species composition of benthic communities was similar between sampling points but the highest density of black flies was found where turbidity was lowest.

Monitoring on benthic organisms and turbidity measurements


Þjórsá and Tungnaá catchment areas

Landsvirkjun has monitored the Þjórsá freshwater ecosystem for years and extensive research has been conducted on fish stocks there since 1973. The water flow in the lower regions of Þjórsá has changed since the power stations in the area were constructed. Sedimentation levels have dropped and general conditions have improved for the salmon population, supporting its growth and increasing ‘fish catch’ in the river. Landsvirkjun constructed a fish ladder by the Búði Waterfall in 1991. Migration has increased via the fish ladder between years and salmon now spawns above the fish ladder.


Þjórsá and Tungnaá Rivers catchment areas


Fish migration in Þjórsá and Tungnaá

A report on fish stock research in the Þjórsá catchment area was released by the Institute of Freshwater Fisheries in 2013. The objective of the research was to increase expertise on salmon migration and to assess the condition of fish stocks in the area, in connection with potential power projects in the lower regions of Þjórsá. The main results were as follows:

  • An assessment showed that over 3000 salmon smolt had migrated down river in the Kálfá River and approx. 20% of these were tagged in an attempt to assess the size of the population on their return in 2013 and 2014.
  • The density of juvenile salmon in their first and second year, above the fish ladder, by the Búði Waterfall, was the highest ever recorded in the area. This is confirmation that salmon habitat is now increasing above the ladder and recruitment is active.
  • The density of juvenile salmon in their first and second year found at annual monitoring stations in Þjórsá decreased between years whereas the density of juvenile salmon in their second year was at its highest level in 2008.
  • Habitat classification studies were conducted for juvenile salmon in non-passable areas in Bjarnalækur. The results showed that there were many areas that could prove to be suitable habitat for salmon juveniles under the right conditions; water temperature and water flow.

Búðarháls Hydropower Station is the latest addition to Landsvirkjun’s hydropower station network and the station began operations in March, 2014. The Station harnesses water from Tungnaá and Kaldakvísl where Arctic char and Brown trout stocks exist (the Brown trout is dominant in the area). The main angling areas in the vicinity of the Station are found in the catchment area of the Tungnaá and Kaldakvísl Rivers below the Nefji Waterfall.

A report was released on research conducted on Brown trout and Arctic char migration in the affected areas of the Búðarháls Hydropower Station in 2013. The research was conducted between 2009 and 2012, before the Station began operations. The main results were as follows:

  • The construction of Sporðöldulón Reservoir prevents the free migration of trout between Kaldakvísl and Tungnaá and this will subsequently affect angling opportunities in the water system.
  • There are indications that the population could be divided into two separate groups; one in Tungnaá and the other in Kaldakvísl.
  • Spawning areas within the reservoir site will disappear as a result of the construction of Sporðöldulón and the Kaldakvísl population will need to move further up river to survive. The Tungnaá population will also need to adapt to new spawning conditions.

The freshwater ecology of the Sog area

The Sog River originates from the Þingvallavatn Lake which is the largest natural lake in Iceland. Three hydropower stations operate in the Sog area: Steingrímsstöð Station, Ljósafoss Station and Írafoss Station. The natural run-off from Þingvallavatn was in the Efra- Sog area before the Steingrímsstöð Hydropower Station was constructed. The water is now channeled via tunnel into the Station and subsequently flows into Úlfljótsvatn. Efra-Sog was known for its large sized Brown trout and its large black fly population, which is important for the salmonid population.


The Sog catchment area


Freshwater ecology in the Sog area

The Institute of Freshwater Fisheries has conducted research on fish, with an emphasis on monitoring juvenile salmon conditions in the Sog area since 1985. Aquatic invertebrates (with a special focus on black flies) have been monitored in the Sog and Efra-Sog area since 1997. The results from the 2012 monitoring of aquatic invertebrates and fish in the Sog River and its tributaries and Efra-Sog was published in a report in 2013. The main results were as follows:

  • Salmon fishing figures were good in the Sog area in 2011 or 66% over the average for the last 10 years. However, there was a significant decrease in numbers in 2012 or 55% under the average for the last 10 years. This is consistent with generally low angling numbers and salmon numbers in the country’s river system that year.
  • There has also been a decrease in Arctic char numbers in the Sog area since 2000. In 2012 and 2013, Arctic char accounted for approx. 16% of angling in 1996. The decrease reflects the decrease in population in the Sog area and is consistent with an overall decrease in the population in Icelandic rivers. This decrease has been ongoing since 2000 and there are no obvious reasons for this development.
  • Conditions for juvenile salmon in their first year were good in the Sog area in 2012. Salmon recruitment was successful in the upper regions of the Sog area. There has been a poor density of juveniles in this area for the last few years. Salmon juveniles were recorded in comparative areas in the lower regions of the water system (in Ölfusá and Hvítá). Brown trout has been recorded in the outflow of Þingvallavatn and in Efra-Sog in the last few years, indicating spawning activity in the area.
  • The number of black flies found in traps in the Sog area was consistent with the average between 2007-2011.