Stream restoration

Naamankajoen kunnostustalkoot. Kivien siirtoa veden virtaaman muuttamiseksi.

Rivers and brooks have faced tough times over the years: they have been cleared and dammed, and their channels have been straightened. Can streams be restored, and is it worthwhile?

Very few rivers and brooks remain in their natural condition in Finland, and many lotic biotopes are threatened. Restoration can help stream habitats to recover and their typical plant and animal species to return, which also increases the recreational value of streams.

To restore a river or a brook, it may be necessary to take action in its surroundings, such as intervening in excessive loading in the catchment by tackling emission sources.

The restoration measures in an actual river or brook vary depending on the site. If the channel has been dammed or contains other barriers and man-made structures, the possibility of removing them should be considered. For this, an environmental permit may be needed. Finally, the channel is restored with increased diversity and varying flow conditions as the aim.

A stream can be restored by introducing into its channel timber, gravel and stones – the very same materials that may have been removed from it in previous eras. This results in fluctuations in the flow rate, recreating the natural interplay of rapids and pools in the river. As a meandering channel provides shelter for fish and suitable habitats for benthic animals, restoration can create a diverse stream environment in which fish are able to reproduce.