The West Middle Cheliff watershed is located in the north-west of Algeria. It has an enormous potential alluvial groundwater and belongs to three sub-watersheds named: Wadi Ras Ouahrane, Wadi Sly and Wadi Cheliff Ouarizane. The Sidi Yakoub dam water releases on Wadi Sly for agricultural purposes have influence on the wadi flow and on the piezometric groundwater outside the flood seasons. The study region piezometric fluctuations of both time and space allows showing a general groundwater flow direction from East to West and in the South from Wadi Sly to the centre, suggests a connection of groundwater recharge by Sidi Yakoub releases. To these effects, it is undoubtedly a piezometric dome appearance on the wadi Sly left bank and water concentrations become diluted in the low water period of 2015.