Conducting one of the largest stream restoration projects in Northern Europe, Denmark restored the natural channel morphology of the lower Skjern River. From 1962 to 1968 the lower Skjern was channelized and diked, and 4000 ha of adjacent wet meadow was drained and converted into arable land. Eliminating the meanders in the river, significantly reducing the total length, and eliminating the river floodplain interaction greatly altered the physical structure of this ecosystem. In turn, both biological and chemical components of this river/wetland ecosystem were negatively affected. For example, spawning habitat for Atlantic salmon was reduced and waterfowl populations decreased. Nutrient and sediment loads from agricultural fields and fish farms, and ochre (iron oxides that are toxic to aquatic organism) transport from drained meadows, into Ringk0bing Fjord increased. In addition, the drained land was subsiding due to loss of groundwater and peat oxidation.
In 1987, the Danish Parliament made the decision to restore the lower part of Skjern River and its valley. The project goal was to restore the nutrient retention capacity of the river basin, restore wetland biodiversity, and increase the recreational and tourist values of the area. This was to be accomplished by returning the river to its former meandering course wherever possible, and removing the dikes along the river so nearby meadows could be flooded. Dikes would be built where necessary to protect farmland outside the project area from flooding. The restoration project costed 234 million DKK (about $40 million). Straightening the river 30 years earlier costed 30 million DKK (approximately $4 million).
River channel construction began in June 1999 and was largely completely by December 2002. Currently, the project has re-established approximately 2200 ha of wet meadow and lakes along the lower Skjern River, increased wildlife populations in the river and Skjern delta, and reduced pollutant loading into the Fjord. Biodiversity has improved throughout the restoration area. Waterfowl populations have increased, including the return and breeding of threatened bird species such as the Spoonbill and Bittern. Atlantic salmon populations have rebounded; however, artificial propagation will likely be needed for a number of years. Otter numbers dropped after draining of the delta and this species was at risk of disappearing altogether. The restored river channel and delta improved the conditions for the otter and will likely cause numbers to increase. This improvement in ecological integrity has been attributed to a more natural river-floodplain interaction created by the reinstallation of meanders in the channel and the removal of dikes.
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