Water Quality Assessment of Lake Manzala, Egypt: A Comparative Study

Lake Manzala is the largest Egyptian lagoon which is considered as one of the most important fishing sources in Egypt. The lake faces a lot of environmental challenges which affect its water quality status. The main objective of this study is assessing the water quality status of the lake using an appropriate Water Quality Index (WQI). Records for twelve water quality parameters during the period from August 2010 to August 2012 were collected from 11 stations in the lake and from 4 stations at the drains outlets. Two Water Quality Indices (National Sanitation Foundation WQI and Lagoon WQI) and a GIS tool were used to assess and spatially assign the water quality conditions of the lake. The results reveal critical water quality conditions for the lake. The eastern and southern zones of the lake have the worst water quality conditions, ranking as a "Very Bad" water quality status, according to L-WQI. While the western zone of the lake has the best water quality condition, which is "Good", according to L-WQI. Bahr Elbaqar drain has the worst water quality status "Very Bad", among the studied drains, which affect the water quality conditions of the lake, in particular the eastern zone of the lake. The worst water quality status of the lake was recorded in August 2011, according to both used indices. The spatial assigning of the lake water quality conditions ensures that the lake should be divided into different zones for fishing and other objectives. An urgent water quality management strategy should be implemented for the lake.