Small watercourses are contaminated with large numbers of herbicides, fungicides and insecticides. A study commissioned by the Federal Office for the Environment and published today shows that the legal requirements specified for water quality are not met in any of the five Swiss streams investigated. Indeed, thresholds for acute toxicity to aquatic organisms were also exceeded. Bioassays indicate that biological communities are adversely affected by mixtures of substances. Measures to improve water quality are currently being developed in the national “Action Plan on risk reduction and sustainable use of plant protection products”.