A north of Amsterdam rangeland located refuse dump, heavily contaminated with organochlorine waste compounds originating from 2,4,5-T production exerts its pollution effects on the surrounding area through the main drainage canal. Compounds demonstrated to be present thus far are the chlorobenzenes, chlorophenols, hexachlorocyclohexanes and the chlorodioxins, mainly 2,3,7,8-TCDD. Analysis of bottom sediments in the drainage canal was positive for 2,3,7,8-TCDD. Concentrations varied between 50 and 5,000 ppt on a dry weight basis. Lowest concentrations occurred in a small pond at about 1 kilometer distance from the dump. Sediment samples were analyzed by two laboratories, totally independent of one another. Results showed a fairly good agreement. Eel caught from the same aquatic habitat had about 1 ppt of 2,3,7,8-TCDD in its tissue. This was lower than calculated levels, based on knowledge of water-sediment partition coefficient and biological accumulation factors.