The dispute now centers on how quickly Ethiopia should fill and replenish the reservoir and how much water it releases downstream in case of a multi-year drought CAIRO: The US envoy for the Horn of Africa was in Sudan on Friday, the latest stop on his tour of the region aimed at resolving the decade-long dispute over Ethiopia’s massive dam on the Nile River’s main tributary. During his two-day visit, Jeffrey Feltman is expected to hold talks with Gen. Abdel-Fattah Burhan, head of Sudan’s ruling sovereign council, Prime Minister Abdalla Hamdok and foreign and irrigation ministers, the state-run news agency reported. Feltman is to discuss the ongoing dispute between Ethiopia on one hand, and Sudan and Egypt on the other over Addis Ababa’s filling of the reservoir on the Grand Ethiopian Renaissance Dam on the Blue Nile. The dispute has exacerbated concerns of an escalation into a military conflict that could threaten the entire region. The dispute now centers on how quickly Ethiopia should fill and replenish the reservoir and how much water it releases downstream in case of a multi-year drought. The latest round of African Union-brokered negotiations in April failed to make progress. Egypt and Sudan argue that Ethiopia’s plan to add 13.5 billion cubic meters of water in 2021 to the dam’s reservoir is a threat to them. Cairo and Khartoum have called for the US, the UN, and EU to help reach a legally binding deal. The agreement would spell out how the dam is operated and filled, based on international law and norms governing cross-border rivers. Egypt, which relies on the Nile for more than 90 percent of its water supplies, fears a devastating impact if the dam is operated without taking its needs into account. Ethiopia says the $5 billion dam is essential, arguing the vast majority of its population lacks electricity. Sudan wants Ethiopia to coordinate and share data on the dam’s operation to avoid flooding and protect its own power-generating dams on the Blue Nile, the main tributary of the Nile. The Blue Nile meets with the White Nile in Khartoum, from where it winds northward through Egypt and flows into the Mediterranean Sea.