Trends of pesticides in Norwegian streams and rivers (1996-2000)

In Norway twelve streams and medium size rivers have been monitored for pesticides in a four to six years period. During these years the central authorities have accomplished efforts to minimize the risk for pesticides entering the water bodies. Trend analyses have been done on the years 1996-2000 to gain information on whether there have been reductions in the retrieval of the pesticides: (1) Frequency of pesticides detection; (2) Sum concentration of all individual pesticides in each sample; (3) Environmental risk by weighing the concentration of each pesticide against the environmental maximum residue limits (MRL). As a whole, developments in streams and rivers show both positive and negative trends regarding the different parameters studied. The tendency is that the different parameters show the same development within the stream. The situation in these streams has not changed much during this 5 years period, but there are indications towards a slight positive development. Trend analyses might therefore be useful together with careful interpretation.