The Grand Ethiopian Renaissance Dam (GERD or TaIHiGe; , , ), formerly known as the Millennium Dam and sometimes referred to as the Hidase Dam (, ), is a gravity dam on the Blue Nile River in Ethiopia. The dam is in the Metekel Zone of the Benishangul-Gumuz Region, close to the border with Sudan.
Constructed between 2011 and 2025, the dam's primary purpose is electricity production to relieve Ethiopia's acute energy shortage and to export electricity to neighbouring countries. With an installed capacity of 5.15 gigawatts, the dam is the largest hydroelectric power plant in Africa and among the 20 largest in the world.
The first phase of filling the reservoir began in July 2020 and in August 2020 the water level rose to an altitude of 540 metres (40 metres higher than the bottom of the river, which is at an altitude of 500 metres above sea level). The second phase of filling was completed on 19 July 2021, with water levels rising to an altitude of around 575 metres. The third filling was completed on 12 August 2022 to an altitude of . The fourth filling was completed on 10 September 2023 with water levels around . The fifth and last filling was completed in October 2024, with a final water level . The plant was formally inaugurated on 9 September 2025.
On 20 February 2022, the dam produced electricity for the first time, delivering 375 MW to the grid. A second 375 MW turbine was commissioned in August 2022. The third and fourth 400 MW turbines were commissioned in August 2024. The dam's official opening was 9 September 2025.
Background The name that the Blue Nile river takes in Ethiopia ("Abay") is derived from the Ge'ez word for 'great' to imply its being 'the river of rivers'. The word Abay still exists in Ethiopian major languages to refer to anything or anyone considered to be superior.
The site chosen for the Grand Ethiopian Renaissance Dam was identified by the United States Bureau of Reclamation in the course of the Blue Nile survey, which was conducted between 1956 and 1964 during the reign of Emperor Haile Selassie. However due to the coup d'état of 1974, Somalia's invasion of Ethiopia in 1977–78, and the 15-year-long Ethiopian Civil War, the project did not progress until the early 2000s. The Ethiopian Government surveyed the site in October 2009 and August 2010. In November 2010, a design for the dam was submitted.
On 31 March 2011, a day after the project was made public, a US$4.8 billion contract was awarded without competitive bidding to Italian company Salini Impregilo, and the dam's foundation stone was laid on 2 April 2011 by the Prime Minister Meles Zenawi. A rock-crushing plant was constructed, along with a small air strip for fast transportation. The expectation was for the first two power-generation turbines to become operational after 44 months of construction, or early 2015.
Egypt, located over downstream of the site, opposes the dam, which it believes would reduce the amount of Nile water available to Egypt. Zenawi argued, based on an unnamed study, that the dam would not reduce water availability downstream and would also regulate water for irrigation. In May 2011, it was announced that Ethiopia would share blueprints for the dam with Egypt so that the downstream impact could be examined.
The dam was originally called "Project X". After its contract was announced, it was called the Millennium Dam. On 15 April 2011, the Council of Ministers renamed it Grand Ethiopian Renaissance Dam. Ethiopia has a potential for about 45 GW of hydropower. The dam is being funded by government bonds and private donations. It was slated for completion in July 2017.
The potential impacts of the dam have been the source of international controversy. Egypt depends on the Nile for about 90% of its water. The Government of Egypt demanded that Ethiopia cease construction on the dam as a precondition to negotiations, and some political leaders have discussed methods to sabotage it. Egypt planned a diplomatic initiative to undermine the dam's finance and construction provided by Norway and Italy. However, governments of other countries in the Nile Basin Initiative expressed support for the dam. This includes Sudan, the only other nation downstream of the Blue Nile, although Sudan's position towards the dam varied over time. In 2014, Sudan accused Egypt of inflaming the situation.
Ethiopia denies that the dam will have a negative impact on downstream water flows and contends that the dam will, in fact, increase water flows to Egypt by reducing evaporation on Lake Nasser. Ethiopia has accused Egypt of being unreasonable. In October 2019, Egypt stated that talks with Sudan and Ethiopia over the operation of a $4 billion hydropower dam that Ethiopia is building on the Nile have reached a deadlock. Beginning in November 2019, U.S. Secretary of the Treasury Steven T. Mnuchin began facilitating negotiations among the three countries.
Cost and financing The Grand Ethiopian Renaissance Dam (GERD) is estimated to cost close to 5 billion US dollars, about 7% of the 2016 Ethiopian gross national product. The lack of international financing for projects on the Blue Nile River has persistently been attributed to Egypt's campaign to keep control of Nile water sharing. Ethiopia was forced to finance the GERD with crowdsourcing through internal fundraising in the form of selling bonds and persuading employees to contribute a portion of their incomes. Contributions are made in the newly official website confirmed by the verified account of the Office of the Prime Minister of Ethiopia
Of the total cost, 1 billion US dollars for turbines and electrical equipment was funded by the Exim Bank of China.
Design The design changed several times between 2011 and 2019. This affected both the electrical and storage parameters.
Originally, in 2011, the hydropower plant was to receive 15 generating units with 350 MW nameplate capacity each, resulting in a total installed capacity of 5,250 MW with an expected power generation of 15,128 GWh per year. Its planned generation capacity was later increased to 6,000 MW, through 16 generating units with 375 MW nominal capacity each. The expected power generation was estimated at 15,692 GWh per year. In 2017, the design was again changed to add another 450 MW for a total of 6,450 MW, with a planned power generation of 16,153 GWh per year. That was achieved by upgrading 14 of the 16 generating units from 375 MW to 400 MW without changing the nominal capacity. According to a senior Ethiopian official, on 17 October 2019, the power generation capacity of the GERD is now 5,150 MW, with 13 turbines (2x 375 MW and 11x 400 MW) down from 16 turbines.
Not only did the electrical power parameters change over time, but so did the storage parameters. Originally, in 2011, the dam was planned to be tall with a volume of 10.1 million m³. The reservoir was planned to have a volume of and a surface area of at full supply level. The rock-filled saddle dam beside the main dam was planned to have a height of meters, a length of and a volume of 15 million m³.
In 2013, an Independent Panel of Experts (IPoE) assessed the dam and its technological parameters. At that time, the reservoir sizes were changed already. The size of the reservoir at full supply level went up to , an increase of . The storage volume at full supply level had increased to , an increase of . These numbers did not change after 2013. The storage volume of represents nearly the entire annual flow of the Nile.
After the IPoE made its recommendations, in 2013, the dam parameters were changed to account for higher flow volumes in case of extreme floods: a main dam height of , an increase of , with a length of (no change) and a dam volume of , an increase of . The outlet parameters did not change, only the crest of the main dam was raised. The rock saddle dam went up to a height of , an increase of , with a length of , an increase of . The volume of the rock saddle dam increased to , an increase of .
Two dams
The zero level of the main dam, the ground level, is at an elevation of about above sea level, corresponding roughly to the level of the river bed of the Blue Nile. Counting from the ground level, the main gravity dam is tall, long and composed of roller-compacted concrete. The crest of the dam is at an elevation of above sea level. The outlets of the two powerhouses are below the ground level, therefore the total height of the dam is slightly higher than the given height of the dam. The structural volume of the dam is . The main dam is from the border with Sudan.
Supporting the main dam and reservoir is a curved long and high rock-filled saddle dam.634-DESIGN-OF-GRAND-ETHIOPIAN-RENAISSANCE-RCC-MAIN-DAM-H-175-m-Pietrangeli-Bezzi-Rossini-Masciotta-DAlberti-2017.pdf The ground level of the saddle dam is at an elevation of about above sea level. The surface is concrete to keep the interior dry. The saddle dam is just away from the border with Sudan, much closer to the border than the main dam.
The reservoir behind both dams has a storage capacity of and a surface area of when at full supply level of above sea level. The full supply level is therefore above the ground level of the main dam. Hydropower generation occurs between reservoir levels of , the so-called minimum operating level, and , the full supply level. The live storage volume, usable for power generation between both levels is therefore . The first of the height of the dam is a dead height for the reservoir, leading to a dead storage volume of the reservoir of .
Three spillways The project has three spillways, the primary used approximately 18,000 cubic meters of concrete. These spillways together are designed for up to , the probable maximum flood event.634-DESIGN-OF-GRAND-ETHIOPIAN-RENAISSANCE-RCC-MAIN-DAM-H-175-m-Pietrangeli-Bezzi-Rossini-Masciotta-DAlberti-2017.pdf All waters from the three spillways will discharge into the Blue Nile before the river enters Sudanese territory.
The main gated spillway is located to the left of the main dam and is controlled by six floodgates with a design discharge of in total. The spillway is wide at the outflow gates. The base level of the spillway sill is at , well below the full supply level.
An ungated spillway, the auxiliary spillway, sits in the centre of the main dam with an open width of about and a design discharge of .634-DESIGN-OF-GRAND-ETHIOPIAN-RENAISSANCE-RCC-MAIN-DAM-H-175-m-Pietrangeli-Bezzi-Rossini-Masciotta-DAlberti-2017.pdf This spillway has a base-level at , which is exactly the full supply level of the reservoir. The dam crest is higher on both sides of the spillway. This ungated spillway is only expected to be used when the reservoir is both full and the flow exceeds , a flow value projected to be exceeded once every ten years.
A third spillway, an emergency spillway, is located to the right of the curved saddle dam, with a base level at . This emergency spillway has an open distance about along its rim. This third spillway will discharge water if river flow exceeds , corresponding to a flood event once every 1000 years.634-DESIGN-OF-GRAND-ETHIOPIAN-RENAISSANCE-RCC-MAIN-DAM-H-175-m-Pietrangeli-Bezzi-Rossini-Masciotta-DAlberti-2017.pdf
Power generation and distribution Flanking either side of the auxiliary ungated spillway at the centre of the dam are two power houses, that are equipped with 2 x 375 MW Francis turbine-generators and 11 x 400 MW turbines. The total installed capacity with all turbine-generators will be 5,150 MW. The average annual flow of the Blue Nile being available for power generation is expected to be , which gives rise to an annual expectation for power generation of 16,153 GWh, corresponding to a plant load factor (or capacity factor) of 28.6%.