The Grand Ethiopian Renaissance Dam, situated snuggly between Ethiopia, Egypt, and Sudan on the Blue Nile, has brought years of controversy to the Horn of Africa. Adding to that tension, water started pooling in the dam’s reservoir in July, absent an agreement between the three countries on how the process to fill the dam would proceed.

Construction on the massive dam, Africa’s largest hydropower project, began in early 2011, yet conflict over water access, energy, and natural rights between the three countries is ongoing.

After years of intermittent negotiations, talks resumed in June this year with a hope that the countries could come to a compromise before Ethiopia began to fill the reservoir. No understanding was reached. An agreement facilitated by the United States and the World Bank was almost concluded in February this year, yet Ethiopia declined to sign the drafted agreement, claiming that the United States overstepped its observer roll and favored Egypt. The main sticking points are the procedures for operating the dam during dry periods and how disputes will be resolved.

Ethiopia plans to use the Blue Nile, the main tributary of the Nile, for energy generation and economic development, according to the International Crisis Group. Due to the upcoming rainy season, the country deemed filling the reservoir a priority. Downstream countries Egypt and Sudan fear this work will limit their access to water and flood security respectively, though Sudan could gain from the dam’s hydropower as well. Ethiopia noted that the dam will take seven years to fill, but construction should be completed by 2022 or 2023. Water is already high enough to begin testing two of its turbines.

Half of Sudan is desert, and the country’s irrigation minister claims that flows from the Blue Nile have dropped 90 million cubic meters per day since Ethiopia began filling the dam. Egypt, nearly of all which is desert, depends on the Nile for 90 percent of its water needs. The Egyptian Ministry of Foreign Affairs reaffirmed in February that the country would protect its Nile water supply by all available means.

In an interview with VOA, Mirette Mabrouk, senior fellow and director of the Middle East Institute’s Egypt Studies Program, said that there could be more tension between the three countries, but military conflict would be last on the list.

"Nobody wants that kind of conflict. But I do think that if Egypt and Sudan have their backs up against the wall, it may be a final option," Mabrouk told VOA. "At least possibly for Egypt, with the understanding that Egypt understands very, very well that any military option is really not going to be in anyone’s favor."

Last week, the African Union called on the three countries to restart negotiations and approve a binding agreement. Yet, the Ethiopian Foreign Ministry announced the same day that it would seek more flexible arrangements that could be modified as needed.

In an attempt to negotiate with Ethiopia, the Trump administration may hold back aid until the country budges on the dam. Though military intervention is an unlikely prospect, the dam could prove to be a thorn between the three countries for years to come.