The urban, industrial and artisanal wastes liquid of the town of Fez have a very remarkable impact in the valley of Sebou. For that, various samples of sediments, agricultural grounds and plants were collected upstream like downstream from the junction Oued Fez- Oued Sebou along about thirty the kilometers; and analyzed by the method of the optical spectrometry of emission to source of plasma in inductive coupling (ICP-OES). These analyses enabled us to evaluate the contents of heavy metals such as: Ba, Zn, Cr, Ni, Co, Cd, Pb, Cu and others. All the results record a high degree of contamination of the metal elements to the state of trace in samples of sediments, grounds and plants irrigated with worn water containing of the particles of suspended materials. We could establish significant correlations of each metal for the various compartments of the ecosystem.