Emergency Release Point at Hänggelgiessen, Overload

The aim of the "Linth 2000" project is to protect the plains between Näfels/ Mollis and the Obersee (Lake Zurich) from flooding. The existing hydro-engineering facilities of the Linthwerk shall be comprehensively overhauled so that a 100-year flood can be diverted without damage. Also extreme flooding can be managed without largescale damage. The overload concept intends to divert discharge above the overload capacity before reaching the dam of the Linth Canal into a trench on the right.

The release point is located where the river is widened at Hänggelgiessen and was constructed in the form of a controlled flap (width 15 m, dam height 2.20 m). The terrain of the Schänner plain thus creates a retention area of approximately 1 million m3 into which water from the Linth can flow back so that the discharge capacity of the right trench is not exceeded.


Linth Administration, Lachen


IUB Engineering AG in consortium

Construction period

2009–2014 (implementation 2009-2013)

Construction costs

CHF 104.5 million; Emergency release point approx. CHF 1 million

Scope of services

  • Project stages processed: clarifications, preproject, participatory procedure during approval stage of the construction project, design approval project, consultation during approval stage and appeals process, implementation of immediate measures for the Escherkanal, construction supervision for the whole project from 2007.
  • Planning of dam rehabilitation works, new lateral tributaries, ecological measures, costing for construction design, transport and development concepts, addressing overload, dealing with historical structures, construction in protection zones.