To evaluate the landfill leachate impact on the stream water quality, we assessed the spatial evolution of several abiotic and biotic parameters in Etueffont domestic landfill (Belfort, France). The samples were taken in 13 June 1999 with a Van-Dorn bottle from upstream to downstream. The study showed that leachate rejection resulted in an increase of the pH, NO 3 -, Cl -and COD concentrations in the first meters after rejection. In downstream, however the reverse was quoted. Bacterial abundance increased from upstream to downstream with no relationship between this biological compartment and leachate rejection. Finally, it seems likely that the abilities of self regulation of brook were higher to the leachate-induced pollution.