Assessing the drain estuaries’ water quality in response to pollution abatement

To assess 12 years of pollution abatement efforts in all drain estuaries in Northern Egypt, which discharge to Northern Lakes and the Mediterranean Sea, this paper provides temporal trends in water quality indices from 2002 to 2013. For the estuary of 20 drains: one drain had insufficient data to analyze for trends (Burullus Drain), four drains had significant increase in water quality index (WQI) score (Bahr ElBaqar Drain, Drain No. 1, Tabia Drain and No. 11 Drain), one drain had significant declination in water quality score over the tested time period (Ramsis Drain). While the rest (14 drains) showed insignificant trend in either direction (improving or declining). Water quality fluctuated over that time period. On average, temporal changes in excursions of coliform count from their threshold can explain 83.3% of the temporal variability observed in water quality indicators monitored in all drain estuaries (38.9%% < R2 < 89.2%). Therefore, the most effective water quality variables among a set of variables affecting the WQI score was total coliform.