The ‘Platzspitzwehr’ is a weir at the confluence of the Sihl and Limmat rivers, which was put into operation in 1951 and serves to regulate Lake Zurich. The two ageing weir fields must be replaced. The renewal of the Platzspitzwehr with a continuously operating two-field sector weir is necessary to achieve more flexible and improved weir control to regulate the lake level and Limmat drainage (to reduce the risk of flooding). It thus protects the communities along Lake Zurich as well as downstream of the Limmat from flooding.
The project also includes the construction of a fish ladder as a ‘Mäander’ (meandering) fish pass in the existing central dam. In addition, a new access bridge will be built on the site of the historic Mattensteg bridge to allow for maintenance work on the weir. The old Mattensteg bridge will be dismantled and rebuilt upstream at a suitable location.

TBF provides project support to the canton, which involves many stakeholders due to its central location in the middle of Zurich.