Flash floods cause water from Wadi Qumran to cascade down these limestone cliffs. During dry periods, the water’s path is marked by a white trail worn into the cliff face. The Qumranites built a dam at the end of one waterfall, carefully channeling the water into basins throughout their settlement. The use of channels to drain rainfall into serviceable pools was common in Judean desert settlements of the late Second Temple period (37 B.C.E.–70 C.E.).