Water quality as well as phytoplankton qualitative and quantitative compositions of different aquatic habitats (Lake Nasser, fish ponds, and potable water) in a reclaimed cultivated area on the west shore of Lake Nasser were investigated in winter of 2007. In spite of the sampling sites were located in close proximity, the data obtained may indicate that the different water habitats acquired specific environmental conditions and man-made effects. The relatively alkaline pH value and oxygen super saturation of the majority of water samples may be in part attributed to the photosynthetic activity of phytoplankton. The differences that were recorded in nutrient concentrations of the collected water samples could be mainly due to the phytoplankton density, human activity in the vicinity of sampling sites in Lake Nasser, or due to manuring with various nutrients in fish ponds. The structure of phytoplankton assemblages revealed a floristic diversity and composed of various species appertaining to green algae, diatoms, cyanobacteria and dinoflagellates. Numerically, diatoms dominated the phytoplankton community in Lake Nasser and drinking water habitats. However, in fish ponds, green algae represented the dominant group. Species diversity did not differ significantly among the three investigated habitats. The sustainable management plan of the aquatic ecosystems in this region should include establishment of environmental monitoring system in order to record any alterations that may take place in water quality. For potable water supply, maintenance of high-quality water should be among the principal priorities in management plans