introduction

Switzerland's streams and rivers form part of a landscape that is used intensively and for a wide variety of purposes by man. Watercourses are surrounded by settlements, farmland and roads; they are dammed up for power generation purposes; they are modified by flood protection structures; and they serve as receiving waters for purified wastewater from treatment plants. These types of use are heavily impacting natural river and stream ecosystems

In the mid-twentieth century, waterbodies were heavily polluted by municipal wastewater. Following the implementation of the Water Protection Law (first introduced in 1955), chemical pollution was significantly reduced as a result of the construction of wastewater treatment plants. However, while foul-smelling, foaming streams are largely a thing of the past, watercourse ecosystems are still influenced by human activities: the expansion of hydropower, the development of settlements and transport infrastructure, and the intensification of agriculture are increasingly restricting the space available for watercourses and leading to the degradation of habitats for plants and wildlife.

Integrated water protection requires accurate knowledge of the current state of waterbodies. It is thus necessary to investigate not only water chemistry but also communities of animals and plants, as well as hydrological and structural aspects. The Modular Stepwise Procedure provides a framework for the integrated investigation and assessment of waters. The procedure is based on the concept of integrated protection that underlies the Water Protection Law of 1991, and it comprises a set of methods - so-called modules - from the fields of hydrology and morphology, biology, chemistry and ecotoxicology. Survey steps are classified into three levels of intensity.