Abstract 11 Herbicides have been found in Danish streams in conventionally cultivated areas. A sandy and a clayey catchment survey area was studied. During a two year period soil water, drainage water, stream water and pond water samples were taken regularly. Pesticide concentrations were higher in a clayey, more intensively cultivated area than in a sandy, less intensively cultivated area. Pesticides did occur in pulses which were observed in periods with time integrated automatic sampling.