Ethiopia’s mega dam has taken 14 years to build: What it means for the Nile’s 11 river states & why it’s so controversial

In April 2011, Ethiopia began construction of Africa’s largest hydroelectric dam, the Grand Ethiopian Renaissance Dam (GERD), on the Blue Nile river. The dam is expected to generate more than 6,000 megawatts of electricity, effectively transforming Ethiopia into the continent’s largest power exporter.

The dam affects 11 countries, two downstream and nine upstream.

Addis Ababa completed construction of the $4 billion-plus project in July 2025, mainly with funds sourced from Ethiopians at home and in the diaspora, with an official launch on 9 September 2025. John Mukum Mbaku, who has researched the governance of the Nile’s waters, explains the dam’s potential for Ethiopia — and the controversies that have dogged it.

What are the simmering tensions around the official launch of the dam?

The dispute over the allocation and use of the Nile waters has been going on for many years. This has been exacerbated by climate change, and increased demand for food and water from growing populations.

The 11 countries that share the waters of the Nile have competing development priorities too. These states include Ethiopia, Egypt, Sudan, Rwanda, Tanzania and Kenya.

Egypt and Sudan lie downstream. They receive the river’s waters only after it has passed through the nine upstream states.

Initially, the downstream states, particularly Egypt, opposed the construction of the dam, arguing that it was a threat to their water rights.

However, Ethiopia powered ahead with construction. Egypt and Sudan then shifted negotiations to securing an agreement for filling and operating the dam.

The two downstream states had suggested that filling the dam should take about 12 to 21 years in order to protect their water supply. For domestic and political reasons, Addis Ababa prefered a shorter filling period. In addition, Egypt and Sudan argued that filling the reservoir without a legally binding agreement would disregard their interests and rights.

But with the dam now fully filled and due to be officially inaugurated on 9 September, 2025, the issue of a binding agreement for filling the dam’s reservoir is moot.

Egypt and Sudan’s political and diplomatic efforts highlight what they say is the illegality of unilaterally operating the dam without a binding agreement. Despite the intervention of the African Union and the US government, as well as appeals by Egypt to the UN Security Council, the three countries haven’t been able to secure a deal.

Part of the reason is that Egypt has insisted that any negotiations on water allocation begin with the rights granted to it under its 1959 Nile Waters Treaty with Sudan.

Under this agreement, Egypt was granted 66 per cent of the Nile’s estimated average annual water flow of 84 billion cubic metres. Sudan got 22 per cent. The treaty ignores upstream countries’ legal claims to Nile waters, since 10 billion cubic metres were reserved for seepage and evaporation. Ethiopia’s highlands, for instance, supply more than 86 per cent of the water that flows into the Nile River.

Egypt continues to argue that Ethiopia’s dam is a threat to its water security and that, if necessary, it will take measures to protect what it refers to as its “historical rights” to Nile waters.

Egypt relies on the Nile for more than 90 per cent of its fresh water supplies. The country’s water needs have risen as its population has grown and its economy has expanded significantly.

However, Egypt and Sudan’s insistence on keeping their historical water shares cannot be considered equitable and reasonable. Additionally, Cairo doesn’t appear to be prioritising a water-use approach that acknowledges the legal claims of upstream states to the Nile’s waters.

Instead of improving and updating its water infrastructure, minimising wasteful irrigation practices and generally improving water use, Egypt has focused on grandiose mega projects that are putting significant stress on the region’s scarce water resources.

Sudan, which has been battling a devastating civil war since 2023, has raised concerns about Ethiopia’s dam affecting the operations of its own dams. This would make it more difficult to manage Khartoum’s development plans.

What makes agreement on the Nile so elusive?

The legal framework regulating the allocation of the Nile’s waters has been dominated by colonial-era agreements. These have been embraced by the two downstream states, Sudan and Egypt, but contested by the nine upstream ones.

Two of the most important of these agreements are the 1929 Anglo-Egyptian Treaty and the 1959 Egypt-Sudan treaty.

The 1959 treaty augmented the water allocations granted to Egypt and Sudan by the 1929 Anglo-Egyptian Treaty. These treaties also granted Egypt veto power over any construction projects on the Nile or its tributaries.

The terms of these treaties, however, are only possible if the nine upstream riparian states don’t access or utilise any water from the Nile and its tributaries.

Most importantly, they make the water rights of the other Nile countries dependent on Egypt and Sudan’s goodwill.

Ethiopia and other upstream states have long argued that they were not parties to the colonial-era treaties and are, therefore, not bound by them.

What international principles guide water use across borders?

The pillars of international transboundary water law are:

(i) equitable and reasonable use

(ii) the obligation not to cause significant harm

(iii) the duty to cooperate.

International legal scholars have noted that the 1959 Nile Treaty stands in sharp contrast to these principles. It disregards the sovereign rights of other riparian countries to their fair share of the Nile, and interferes with their development.

What does the dam promise for Ethiopians?

The Grand Ethiopian Renaissance Dam is a symbol of national unity and pride. It is significant that construction was undertaken without reliance on financing from external actors, such as international financial institutions or major industrial countries.

The dam’s electricity output could potentially transform Ethiopia’s development.

First, the electricity would provide a reliable source of energy for rural industrialisation, reducing deforestation by eliminating the need for households to cut down trees for firewood.

Second, it would reduce the pollution associated with burning wood, dung and other forms of biomass for cooking and other activities.

Third, it would improve access to education, effectively providing light that enhances the ability of pupils to complete homework assignments and study at night. During hot seasons, the electricity generated could be used to cool classrooms, improving learning outcomes.

Finally, higher electricity output would boost internet connectivity in rural areas in Ethiopia, effectively boosting access to the outside world.

The dam could also help with flood control in Sudan and drought protection in Egypt — but only if the three countries work together.