Status of lakes and streams

Pesticides found in the aquatic environment

Through the Swedish national environmental monitoring, the status in the environment has been continuously assessed since 2002. Pesticides are analysed in streams in four small catchments and in two rivers. The results of these analyses show that small amounts of pesticides are present in all streams and rivers and that in appoximately one in three samples, one or other compound exceeds the guideline value that indicates that some damage can occur. However, such cases are rather moderate and it is not possible to identify any particular compound that is particularly risky. Between 15 and 20 compounds are found once or twice a year in concentrations that can carry risks for algae and fauna in rivers and streams.

With the help of an estimated toxicity index, it is possible to compare water quality between different sampling areas and within the same area at different times. A higher index value means a greater risk of effects on aquatic organisms. The diagram shows the index values per year for surface water within the four areas where environmental monitoring has been carried out in Sweden since 2002. The changes in the index values show the trend for the cumulative incidence of pesticide residues (per area and year) in relation to the respective guideline values. The diagram shows e.g. that water quality in the sampling area in Skåne improved between 2002 and 2006. Source: Stina Adielsson, SLU.

The River Vemmenhög in Skåne is the only river in Sweden for which there is a long time series of data on concentrations of pesticides. Since the beginning of the 1990s the concentrations have declined dramatically, despite the amount of pesticides used not having decreased. The decrease in concentrations is probably the result of  information campaigns on the risks of handling pesticides. Source: Jenny Kreuger, SLU.