Is the amount of pesticides in Dutch regional surface waters correlated with toxic effects ?

In the low parts of the Netherlands most of the rainwater flows via small ditches and larger waterways to a pumping station. Here the water is pumped into a large water body. Agricultural pesticides are transported via the same route. The concentrations of agricultural pesticides in the ditch adjacent to the field can be relatively high at the moment of application. These pesticides will be diluted when they are transported through larger waterways to a pumping station. In this cooperative reseach program of RIZA and RIVM, pesticides levels were monitored in the water before the pumping station. This program monitors the pesticide content in surface water together with ecotoxicological measurements in the same water samples. This makes it possible to determine whether these pesticides contribute significantly to the toxicity in a number of Dutch surface waters.