New scientific research revealed that the Nile River Delta in Egypt is polluted with heavy metals on a large scale, and its costs are exposed to erosion and seawater intrusion, which constitutes an existential threat to it, and endangers the 50 million Egyptians who live on it and depend on its resources in every aspect of life. Pollution also threatens millions of migratory birds, for whom the Nile Delta is an essential stopover on their journey along the East African flight path.

The study, led by Egyptian scientist Esam Hegy of the USC Viterbi Innovation Fund Arid Climates and Water Research Center, confirms that existing dams in the Upper Nile, such as the Grand Ethiopian Renaissance Dam, in addition to the policy currently in place in Egypt to reuse irrigation water to make up for the lack of fresh water, has a significant impact on the degradation of both soil and water quality. Egypt, the most populous and driest country along the Nile River, has one of Africa’s highest water budget deficits—the large-scale reuse of sewage and agricultural wastewater in the Nile Delta offsets this deficit. There needs to be more research on the effects of water reuse on increasing soil pollution levels. To address this lack of studies, the researchers assessed the level of heavy metal contamination and pollutants along the two branches of the Nile Delta and identified their sources. They also explored how dam construction in the Upper Nile increased the concentration of these pollutants in the delta.

The researchers concluded that widespread pollution, coastal erosion, and seawater intrusion pose severe challenges to the survival of the Nile Delta as a primary source of food security for Egypt. The rapid flow of the Nile, the low gradient of the delta, and the silty soils of the river bed further increase the retention of heavy metals and impede their flow, causing widespread pollution of the delta. The increase in the reuse of sewage and agricultural water for irrigation to mitigate the effects of the water deficit resulting from the dams built in the upper Nile contributes rapidly to the increase of these pollutants.

Pollution indicators show moderate to very high pollution by lead, nickel, chromium, cadmium, copper and zinc, with unprecedented levels of cadmium in the sediments (up to 72.0 ppm) and an increase in pollution levels towards the north. This affects the water and soil quality of the Nile Delta, threatening the social, economic and environmental future of more than 50 million people in one of the world’s largest and most climate-vulnerable river deltas, according to the study. “You have roughly the entire population of California and Florida living in an area the size of New Jersey, which is increasingly polluted by toxic heavy metals,” says Dr Hajji. “Today, a civilization that has thrived in a beautiful aquatic landscape for over 7,000 years must face the reality of this unimaginable widespread environmental irrevocable degradation.”

Egypt needs about 114 billion cubic meters of water annually. Still, the total amount it receives is only 60, including 55 billion cubic meters of its share in the Nile water. The rest is completed through the recycling of agricultural and sewage water. Egypt’s share of the world’s longest river is facing real danger due to Ethiopia’s construction of a massive dam with a reservoir capacity of more than 70 billion cubic meters of water. Ethiopia is currently preparing to start the fourth filling of the Renaissance Dam. At the same time, the Egyptian government cannot protect its historical share in the Nile waters and Addis Ababa’s unilateral policy regarding the construction and operation of the dam. Any expected decrease in Egypt’s share of the Nile water, especially during periods of drought and prolonged drought, will lead to an expansion in the recycling of sewage and agricultural wastewater, which will exacerbate the risks of high levels of water and soil pollution in the Nile Delta, according to the study.

The researchers stress the urgent need to incorporate sediment pollution in the Nile Delta into environmental impact studies of the filling and operation of the GERD. “Our study underscores the need for more research on the environmental impacts of recycling untreated water and the change in river turbidity with an increased damming upstream of the Nile,” says Dr Heggi. “Continuing research with more sampling campaigns in this region could help. Future discussions and cooperation between the Nile Basin countries, who have a common interest in maintaining a healthy system for the Nile.”