The Varde Å river system is the largest river system that flows into the Danish part of the Wadden Sea.
Total catchment area of the river system is approximately 1100 km2. The main tributaries originate west of the Jutlandic ridge, from where they run toward west through the moorland plains and moraine islands from the previous ice age.
The mean water flow of Varde Å at the outfall in Ho Bay is 16,200 l/s, varying from a minimum of 4,200 l/s to a maximum of 60,600 l/s.
The Varde Å river system is the only system where water exchange with the Wadden Sea is not regulated by a sluice. Since there are no summer dikes along the riverbanks the hydrological regime in the lower parts of the river and the adjacent areas is in its natural state. These downstream areas are included in the ongoing Wadden Sea estuary nature and environment improvement project.
Karlsgårde Power Station
The key factor controlling hydrological conditions in central part of the Varde Å system is the hydroelectric power station at Karlsgårde. Downstream the town of Ansager 90 % of the water flow in Varde Å is led into Ansager Cannel to the artificially constructed Lake Karlsgårde . After use for power generating purposes, the water is returned to Varde Å approx. 24 km before the outfall in the Wadden Sea .
Consequently the natural hydrology in the water system is significantly disturbed and the demands for water to the hydroelectric power station courses a severely reduced water flow on 16 km of Varde Å.
Although the weir at Karlsgårde power station are equipped with fish ladders, passage conditions for migratory fish in the Varde Å river system are very poor because of the weir and the disturbance of the natural hydrology – and the houting cannot pass at all.
Spawning areas
Compared to the size of the water system the potential spawning ground area is also relatively low because of the previous hydrological modifications, intensive maintenance (weed cutting) of the watercourses, dredging of the streams and drifting sand.
More than 75 % of the spawning grounds in the Varde Å system is upstream the weirs of the hydroelectric Karlsgårde power station. Furthermore significant potential spawning areas over a distance of 20 km for houting in the original Varde Å has disappeared because of the diminished water flow and modifications to the watercourse.
The project
Restoration of the hydrological continuity and improvement of the physical conditions in Varde Å will promote nature conditions in the water system. This will be of enormous beneficial value not only to the houting but also to all other species in connection to the river.
Besides the very small population of houting, the Varde Å system are of international importance for its populations of Salmo salar, Alosa fallax, Petromyzon marinus, Lampetra fluviatilis and planeri, Lutra Lutra and Margaritifera margaritifera – all listed under Annex II of the Habitats Directive. Varde Å is also designated as a watercourse characterised by Ranunculion fluitantis and Callitricho-Batrachion communities according to Annex I in the directive.
The Houting Project will:
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Close the Ansager Canal and bring the total water flow back into the River Varde Å.
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Decommission the Karlsgårde Power Station
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Widen and remeander the present 13 km heavily modified stretches of the River Varde Å into an approximately 18 km naturally meandering watercourse with good ecological status.
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Establish free passage for houting and all other fish at the fish farm at Sig town.
The project area at River Varde Å