ABSTRACT
There are more than 350 small dams in the Canton of Zurich, Switzerland. Some date back to the medieval ages and many were built between 1750 AD and 1900 AD. Today, these small dams are often protected for environmental or historical reasons. As the Federal Act on Water Retaining Facilities came in force in 2010, the supervision of small dams was handed over from the Federal Government to the cantons. The review of the dams by the Dam Safety Authority of the Canton of Zurich showed that hardly any of these small dams meet the requirements of the Federal Act. In this paper the reasons for dam rehabilitation and some examples of cost-effective measures to improve the safety of small dams are discussed. From several upgrading projects, the renewal of the spillway of the Sülibachweiher near Bauma and the retrofitting of the Sternensee above Richterswil are selected as case studies.
