Water quality and phytoplankton standing crop were monitored seasonally for a year. Seasonal variability in effluent discharge explained much of the variation in water quality parameters; however, deviations from this correspondence were significant.  Nutrient (N and P) concentrations remained low through late fall and suddenly increased, which was hypothesized to be due to turnover in this large, relatively deep river.  Algal biomass increased earlier than nutrients, but decreased rapidly in early winter and remained low for approximately 3 months.  The winter decrease in algal biomass was hypothesized to be caused by elevated turbidity levels in the River Nile - associated with hyacinth removal and channel dredging activities. Diatoms dominated the phytoplankton throughout the year, with greater relative abundances of green algae near the city. Aulacosira granulata was the dominant species throughout the period of study. The city affected water quality by increasing the concentrations of nutrients and most other ionic compounds, as well as algal biomass