During the last glacial period, the Surselva is situated far below the ice mass of the Rhine glacier, which extends up to Southern Germany. At the Flims rockslide almost 9,500 years ago, around 25,000 million tonnes of rock fulminate into the valley. The Vorderrhein dams up to a length of 29 kilometres starting at Valendas to form the 'Ilanzer See'. This lake persists for 100 years after which a catastrophic lake eruption occurs. The water mass erodes through the porous limestone of the Flims rockslide and forms the Rhine Gorge. The Vorderrhein possesses the characteristic trait of a wild and lively stream which runs in a natural, meandering flow through the Surselva, making it an essential basis for the prosperity of diverse flora and fauna.
First signs of settlements in lower Ilanz, in the area of the contemporary old town, date back to the year 765 AD. In the Middle Ages, the two additional settlement centres upper Ilanz and Sontga Clau develop. The latter is situated to the north of the Vorderrhein and is connected with a bridge construction to the two southern districts for the first time in the 13th century.
From the 19th century, two dramatic floods pose a threat for Ilanz, which in the meantime has grown beyond its historical settlement centres towards the river. Subsequently, a number of radical measures are taken and the Vorderrhein is allocated a narrow, regulated canal. In consequence of melioration measures, the previously vast meadows fall victim to newly emerging cultivated land; the Vorderrhein now isolates the southern township from the northern part and is hardly tangible.
Around 1903, the railway line Chur-Ilanz is opened, continuing later on further to Disentis. The route occupies part of the Vorderrhein's southern bank and impedes, like the bypass road of the northern bank, the access to the river.
Forty years later, Axpo Hydro Surselva AG starts operations of the power station near Ilanz which complements the already existing hydropower plants upriver. The use of water for generation of energy leads to strong water gauge fluctuation and is accompanied by increased flow velocity. This circumstance — favoured by the canalization of the Vorderrhein — results in much bed load being transported in the water and the river bed being eroded further. As a consequence, living space of animals and plants is endangered, and local biodiversity deteriorates.
Levelling Stream accomplishes with landscaping a basis for the revitalization of the Vorderrhein banks in Ilanz. The canals serve during rising water levels — caused by rainfall, snowmelt or hydropower — as retention areas to capture changes in current and gauge levels while restoring the natural habitat and rich biodiversity.
The present Rhine bridge requires maintenance. The pavement is now separated from traffic and relocated to the bridge's bottom edge; the inclined headwall guides the pedestrian's view to the newly emerged riverscape.
A pedestrian and bicycle path makes the river bank accessible via four lateral ramps. Reminiscent of a landing stage, they dock onto the Rhine bridge. The elevated train track forms the backbone and protects the built-up municipal area from floods during extreme events.
Levelling Stream regulates the water level and simultaneously makes the river bank once again tangible for people.
Over the decades, flowing water flushes away originally strictly geometrical structures and rearranges them. The landscape changes across generations naturally, and the course of the river returns to a meandering form. Individual fragments of the original linear shaping remain.
In fifty years, forgotten plants thrive at the Vorderrhein in Ilanz, animal species resettle, and people enjoy the return of natural flowing waters. Cityscape and riverscape unite.
