SUMMARY
The Hassan Addakhil dam is situated in the foothills of the central High Atlas. It constitutes an important unit in the bassin Ziz-Guir-Ghriss.The objective of the present study is the characterization of a bacteriological of waters of the dam Hassan Addakhil. To do this, we conducted a monitoring of the evolution of the bacteriological parameters of the water of the dam and water flowing from its Oued Ziz in the year2012. Afaunal study was conducted during the period study.This study revealed the presence of fecal contamination in the Hassan Addakhil dam and the Ziz valley’s waters. The degree of the fecal contamination of the Hassan Addakhil dam waters is lowers than that of the Ziz valley’s, but still may constitute a health risk.