Edit project overview: Case study:Restoration of Kostonjoki River

Please enter a description of the project: Kostonjoki River is one of the tributaries of the River Iijoki. The River Kostonjoki was dredged for timber floating like many other tributaries of the River Iijoki. Before dredging in 1956-1958 there were 105 hectares of rapids and riffles in the Kostonjoki River. After dredging most of the riffles and rapids were destroyed and habitats of the migrating fish lost. Restorations of the Kostonjoki River took place in 2005-2012 as the aim of setting the condition of the water system closer to it´s natural state to enable the fish migration. Object of the restorations was to create pool-riffle variation, add natural water levels to rewater dried parts of the river and add stones and gravel to create habitats for migrating fish. Restorations were successful. Rapid and riffle areas of the Kostonjoki River grew 60% after restorations and densities of migrating fish increased.

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