The water quality of Lake Mariut has been deteriorated for about 5 decades due to continuous discharge of agricultural, municipal, and industrial wastes from Alexandria City and the adjacent land. During the past two decades, some steps were taken for rehabilitation of the lake through primary treatment of the discharged wastes and insulation of the polluted wastewater of QD from the water body in the main basin of the lake. Several parameters of water quality at the surface and near bottom were measured at twelve locations during winter (January) and summer (August) of 2013 and 2014. The present study revealed that the lake water appeared to be well aerated but still containing high concentrations of N and P and suffering hyper-eutrophic conditions. The water quality index (WQI) reflected medium condition in the lake and bad condition in the diverted drains. The P-budget calculation displayed that TP input into the LMMB from UDus and resuspension process from sediments exceeded the output by out flowing at UDds and settling.
Keywords: Alexandria City; Eutrophic lake; Lake Mariut; Phosphorus budget; Rehabilitation; Water quality index.