Physicochemical water quality

Measuring and assessing physicochemical water quality caracteristics

In Switzerland, chemical analysis of surface waters is a practice that dates back several decades. After chemical pollution had reached peak levels in the mid-twentieth century, the introduction of the Water Protection Law in 1955 led to the systematic development of a network of wastewater treatment works. As a result, water pollution from domestic, commercial and industrial sources was substantially reduced. The major advances attributable to structural pollution control measures are readily apparent, particularly in relatively large waterbodies.

Nevertheless, the need for chemical analysis of surface waters remains: water quality is still adversely affected by non-point source inputs, especially agriculture and run-off from sealed surfaces . In some cases, water quality fails to comply with requirements even downstream of treatment works because the amount of treated effluent discharged is disproportionate to the levels of receiving waters or because the degradation of individual substances is inadequate.

Investigations carried out under the Modular Stepwise Procedure are designed to identify sections of watercourses where water quality requirements are not met. While samples for chemical analysis are regularly taken from relatively large streams and rivers, it is not known to what extent many smaller streams are polluted. This gap is to be filled by studies conducted at the regional level (I) in the Chemistry module.

Objectives
Appendix 2 of the Water Ordinance sets requirements for substances that cause problems in the environment. The module «Physicochemical Water Quality» gives advice on selection, sampling and assessment of such substances. In the future, an additional method will be developed to analyze organic substances (micropollutants).

Download of the module Physicochemical Water Quality (in German) Liechti Paul 2010: Methoden zur Untersuchung und Beurteilung der Fliessgewässer. Chemisch-physikalische Erhebungen, Nährstoffe. Umwelt-Vollzug Nr. 1005. Bundesamt für Umwelt, Bern. 44 S. (German version: PDF, ca. 0.74 MB)