The UN Security Council session on Ethiopia’s Nile River dam got heated Thursday as Egypt and Sudan voiced serious disagreements with Addis Ababa on the issue. 

Egyptian Foreign Minister Sameh Shoukry called the Grand Ethiopian Renaissance Dam a “colossal wall of iron and steel that casts a long and dark shadow over the people and fate of Egypt” during the three-hour session. 

Ethiopia started building the massive dam on the Blue Nile in 2011 and started filling it last year. The total filling process will take several years to complete. Ethiopia plans to use the dam to provide electricity to its growing population of more than 100 million. For years, Egypt and Sudan have expressed concerns that unilaterally filling the dam sans an agreement could dangerously lower the river’s water levels in their territories. The Nile is a major source of water for drinking, agriculture and other needs in the region. 

On Monday, Ethiopia informed Egypt and Sudan that the second round of filling had begun. The filling occurs in the summer during East Africa’s rainy season.