Rehabilitation of Platzspitz Weir – Meandering Fish Pass

Fish passability between the River Limmat and Lake Zurich also had to be restored as part of the works to rehabilitate Platzspitz Weir.

At the preliminary design stage, a study of al-ternative fish ladder systems was undertaken. Following a rough classification, alternatives were investigated in detail, namely a vertical slot pass, meandering fish pass, fish locks and fish lifts. The study determined the meandering fish pass to be the best option.

The key characteristic of the meandering fish pass is the exclusive use of round and smooth components, which create a distinct flow with comparatively low turbulence. The compact and space-saving configuration enables meandering fish passes to be installed even in the tightest of spaces.

Main Data

  • Fish region: Grayling region with very diverse stock consisting of at least 22 fish species and salmon holding pool
  • Difference in water level between headwater HW30 and tailwater TW330 of 3.66 m
  • Drop between the pools: 0.15 m
  • Type C meandering fish pass
  • Diameter of pool: 2.4 m
  • Overall width of meandering fish pass: 3.6 m
  • Number of pools: 24


Kanton Zürich – Baudirektion, Amt für Abfall, Wasser, Energie und Luft


IUB Engineering AG in consortium

Construction period


Scope of services

  • Preliminary project
  • Study of alternatives for fish passability
  • Visualization in 3D (Allplan)
  • Design for construction and approval (from autumn 2017)