A model project for Switzerland Ecological upgrading of the River Sihl
The Canton of Zurich and the Swiss Federal Railways are jointly revitalising a section of the Sihl in the Sihlwald forest. The aim of the project is to ecologically enhance the previously monotonous and obstructed Sihl and transform it into a diverse and more lively river. This will not only create new habitats for plants and animals, but also improved conditions for fish migration and a more attractive local recreation area for people.
Over a century ago, rivers and streams were straightened and dammed in many places in Switzerland in order to provide flood protection and gain additional land. Today’s knowledge shows that this has had detrimental consequences for nature. These formerly dynamic and diverse watercourses have become ecologically impoverished and monotonous ribbons of water. The situation is similar in the Sihlwald, whose near-natural habitats for animals and plants have largely disappeared. Fish migration is also significantly impaired by these construction measures. The current revitalization project aims to restore dynamism and diversity to the river area.
Focusing on the project section in Sihlwald
The core of the revitalization project is the river area at the Sihlwald terminus of the Sihltal-Zurich-Uetliberg railroad and the Zurich Wilderness Park Visitor Centre. With a length of around 1.8 kilometers, this section plays a key role in the Canton of Zurich’s revitalization planning and is a top priority. The aim is to enhance the ecological value of this section of the river and thus create new, high-quality habitats that are particularly important for animals and plants.
Through the planned revitalization, those responsible hope to take on a pioneering role in the near-natural development of watercourses and at the same time increase the local recreational value for the population. This integrative approach should serve as a model for similar projects in other regions of Switzerland.
More dynamics, more structure, more habitats
Most of the Sihl’s current bank obstructions will be removed. New structural elements such as islands, large stones and more branches and rootstocks will make the river more diverse and dynamic than it is today. Thanks to a new fish ramp, the Sihl will be more passable for fish and other aquatic life. New ponds as well as wet meadows and rough pastures are also planned. All of these measures will create a variety of new habitats for animals and plants, thereby increasing biodiversity.
On the right bank of the river, a zone will be created that will be reserved for nature. This quiet zone in the popular local recreation area will provide protected retreats for animals. This will benefit the kingfisher, for example, which is very sensitive to disturbance during the breeding season.
Improving the quality of life
The revitalization also makes the river area more attractive for people. Opportunities to spend time by the river and accessible ponds offer visitors insights into nature.
To create a quiet zone for nature on the right bank, the current path below the visitor center will be moved to the left bank of the river. The footpath and cycle path will be separated there. This will give both road users more space. Along the new, varied footpath on the left bank of the river, the vegetation will be repeatedly thinned out. This provides interesting views of the wild riverbank opposite. Small footpaths lead to the river and to natural seating areas by the water. The bridge at the visitor center will be dismantled.
Joint project between the canton ofZurichand SBB
The revitalization of the Sihl is a joint project between the canton of Zurich and SBB. It is part of the environmental measures as part of the new concession for the SBB’s Etzelwerk hydropower plant. The ewz naturemade star fund and the federal government are also making financial contributions.