Julius Nyerere Hydropower Station (JNHPP; JNHS; RHHP; Rufiji Hydroelectric Power Project; Stiegler's Gorge Dam) is a hydroelectric dam across the Rufiji River in eastern Tanzania. The power station has an installed capacity of . The project, power station and dam are owned by and managed by the government owned Tanzania Electric Supply Company (TANESCO). It is the largest hydropower project in Tanzania. Construction began in 2019 and was completed in 2025.
Overview The government of Tanzania has been considering establishing this power station since the 1960s. The dam is the fourth largest in Africa, the ninth largest in the world, and the largest power station in East Africa. The arched, concrete dam creates a reservoir lake, , in length, measuring , with of water. The project, power station and dam are owned by and managed by the government owned Tanzania Electric Supply Company (TANESCO). The power station is expected to produce 5,920 GWh of electricity annually.
History In 1901 German engineer Stiegler led the first expedition to what is now known as Stiegler's Gorge to consider potential infrastructure. Stiegler, when measuring the gorge, was charged and killed by an elephant near the ravine in 1907. It was named after him in his memory. Plans for a dam were developed during British rule of Tanganyika. Alexander Telford conducted the first systematic development surveys of the Rufiji in 1928–1929, with engineer C. Gilman carrying out further studies in 1938–1940. These studies primarily envisioned irrigation infrastructure with a small dam at Stiegler's Gorge to reduce flooding and protect downstream irrigation infrastructure.
This changed in the 1950s when the Food and Agriculture Organization (FAO) started studying Rufiji River infrastructure. This included a far larger dam wall of around that aimed to transform the valley to an artificial environment, providing water for agriculture. The FAO's report was published in 1961 and envisaged of irrigation.
Plans turned towards hydropower after Tanganyika's independence in 1961. President Nyerere saw hydropower dams as key deliverers of his ambitious modernisation programme. From the 1969-1974 Second Five-Year Development Plan, this modernisation plan increasingly aimed for industrialisation and therefore needed cheap electricity. This understanding of dams as developmental and of their ability to deliver cheap electricity, drove the Great Ruaha Hydropower Project with involved hydro-plants at Kidatu and Mtera. The Ruaha is an upstream tributary of the Rufiji.
Planning for the Stiegler's Gorge project advanced with three donor organisations. The Japanese External Trade Organization supported feasibility studies in the 1960s that proposed a 620 MW plant. At the same time, Nyerere's government engaged US Authorities and in particular the Bureau of Reclamation and Tennessee Valley Authority. This produced studies planning wider transformation of the Rufiji valley, with the dam enabling irrigation, industrialisation, urban water supply and a large fishery in its reservoir. The US studies also initiated the creation of the Rufiji Basin Development Authority (RUBADA), whose founding mission was to build the dam and facilitate the wider development of the valley. By the 1970s, the Norwegian NORAD development agency had taken on the Stiegler's Gorge Planning, producing detailed feasibility and construction designs.
However, these plans were never implemented. This is primarily because of the World Bank's decision to reject project finance. In the 1980s, the bank was the major financier of dams in developing countries and particularly significant in Tanzania, which was enduring an economic crisis at the time. The World Bank questioned the need for a dam at Stiegler's Gorge, given their calculation of limited growth in Tanzania's electricity demand. There were also growing environmental concerns around the project, prompting the first Environmental Impact Assessment in Tanzania. These concerns were magnified by the designation of the Selous Game Reserve, in which the gorge sits, as a UNESCO World Heritage Site in 1982. The World Bank and other international donors consequently turned to the smaller and less-impactful Kidatu and Pangani Falls Dams in the 1990s.
However, Kikwete's government resurrected plans for the dam in 2006. This came with the country's emergence from economic crises in the 1980s and 1990s to a period of sustained economic growth. The resurrection of the project also reacted to a severe power crisis in Tanzania from 2004 to 2006 that saw widespread load shedding. Maximising the fiscal advantage of the country's increasing economy, early speeches by government ministers in 2006 indicated that the Stiegler's Dam would be a priority. The Minister of Energy and Minerals also confirmed the dam's status in the 2009 Power Sector Master Plan. The decision gave renewed purpose to Rubada, the agency tasked with implementing the dam, who started actively lobbying for the project and meeting companies.
A series of companies expressed interest in developing the project. Under Kikwete's government, and like other energy sector projects, the dam was supposed to be developed by the private sector. This involved unsolicited bids by private companies for agreements with the government to build the project. The companies would then use these deals, such as power purchase agreements, to raise finance and start construction. The first such bid was made by IDF (Infrastructure Development Finance Ltd) of South Africa and Energen of Canada in 2006–2008. Sinohydro also reportedly placed a bid around 2008.
However, the main engagement came from Brazil. After meetings between Brazilian diplomats and Tanzanian ministers, including the visit of Brazilian president Lula to Tanzania in 2010, both governments agreed to support Stiegler's Gorge Dam's construction. A number of exchanges between the two countries happened between 2009 and 2012. This supported the Brazilian company Odebrecht. They signed a memorandum of understanding with Rubada in 2012 to build the dam. Odebrecht also undertook feasibility and design studies and commissioned an environmental impact report. However, Tanzanian interest in the dam appeared to stall by 2014, delaying any implementation.
This changed when President Magufuli came to power in 2015. In 2017, he announced that the Stiegler's Gorge Dam would be a flagship development project of his government and would be financed by the government rather than developed by the private sector. A first round of bidding for the construction tenders was held in the autumn of 2017. This was unsuccessful, initiating a second round in spring 2018. Arab Contractors and El Sewedy Electric, both Egyptian firms, won the bid. Magufuli has been vocal in denouncing any critics of the dam and his interior minister threatened that opponents would be jailed in a public speech.
As of April 2025, all nine turbines were operational, generating 2,115 megawatts of power. The completed renewable power project was commissioned on 22 August 2026 by Samia Suluhu Hassan, the President of Tanzania. Also present was Mostafa Madbouly, the Prime Minister of Egypt.
Location The dam was built across the Rufiji River, at Stiegler's Gorge, in the Selous Game Reserve, Pwani Region, approximately , by road, southwest of Dar es Salaam.
This power station is located in Selous Game Reserve, one of the world's largest World Heritage Sites, measuring . The power station and reservoir lake occupy approximately , within the game reserve.
Contract In August 2017, the Tanzanian government advertised for bids to construct this dam. The selected contractor is expected to complete the dam in no more than 36 months. The power generated will be transmitted via a new 400kV high voltage power line to a substation where the power will be integrated into the national electricity grid. The government of Ethiopia is advising the Tanzanian government on the implementation of this project.
Although the World Heritage Committee had reiterated its grave concern about Tanzania's decision to move forward on the project and added it to the grounds for the Selous Game Reserve to be on the List of World Heritage in Danger, which grounds previously were only concerned with elephant poaching.
In October 2018, after diplomatic negotiations between Tanzania's President Magufuli and Egypt's President Sisi, the government of Tanzania awarded the design and construction contract for this power project to the Egyptian company Arab Contractors together with the Egyptian manufacturing company El Sewedy Electric, at a budgeted cost of US$2.9 billion (TSh6.558 trillion).
In February 2019, the government of Tanzania handed the construction site over to the contractors. Allowing several months to mobilize equipment, actual construction did not start until the summer of 2019. In April 2019, the Tanzanian government made an upfront payment of US$309.645 million, representing approximately 15 percent total cost of construction.
Redesign and construction
In 2018, a new design for Stiegler's Gorge Dam was unveiled. A 131m high and 700m wide dam wall is under construction. The hydropower plant is planned to have an installed capacity of 2,115 megawatts. If completed on time in 2022, this would be Africa's 2 largest dam by installed capacity, after Ethiopia GERD Dam 5100 megawatts, over Egypt's Aswan High Dam (2100 megawatts), Mozambique's Cahora Bassa Dam (2075 megawatts), and Angola's Lauca Dam (2070 megawatts).
At 2,115 megawatts, the dam's contribution is more than the current peak demand of Tanzania. The country's highest recorded power demand was 1051.27 megawatts in February 2017. Installed capacity has been reported to be between 1366.60 megawatts and 1,602 megawatts. The Stiegler's Gorge Hydropower Project will therefore significantly increase the installed capacity on-grid in Tanzania, supporting power for industrialisation and electrification.
A key rationale for new electricity generation are Tanzania's regular electricity crises. The majority of Tanzania's power shortfalls occur in the dry season and in below-average rainfall years, this causes electricity shortages which are socially and economically damaging. For instance, load shedding between 2014 and 2015 supposedly cost between 5-7% of Tanzania's GDP.
In preparation for the start of construction, Magufuli ordered Tanesco to prepare the site. Contracts were awarded to clear the construction area, prepare a road for large vehicles and provide power and water. The government also handed out rights to log the large reservoir area, which could bring in significant revenue.
Arab Contractors, a public sector Egyptian firm would undertake the civil engineering works while El Sewedy Electric would install the electro-mechanical equipment including the turbines, generators and transmission lines. They signed contracts with the state-owned energy utility company TANESCO. The government has publicly stated that the dam will be financed by Tanzania's national budget, yet no funding package was announced and the World Bank and other financiers rejecting support for the dam. Elsewedy have secured a loan of $500 million from the African Export-Import Bank, with guarantees from the United Bank for Africa and CRDB Bank, which they plan to repay through the project contract. After the allocation of a portion of the national budget for the project in 2018, in February 2019, the government will officially hand over to the contractors.
As of June 2020, the project was 40 percent complete. By January 2021 the bypass tunnel for the dam site was functional and excavation of the 50m deep dam base was in progress. The three head-race tunnels, which will supply nine penstocks for the nine turbines, were under construction. The nine turbines are each to have a capacity of 235 MW. Foundation for the power house was also in progress.