Julius Nyerere Hydropower Station

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 {{convert|134|m|ft}} arched, concrete dam creates a reservoir lake, {{convert|100|km|mi}}, in length, measuring {{convert|1200|km2|mi2}}, with {{convert|34000000000|m3|ft3}} of water.{{Cite web|first=Shem |last=Oirere |date=18 August 2017 |title=Tanzania Revives 2,100-MW Hydro Power Project |publisher=Engineering News Record (ENR) |url=https://www.enr.com/articles/42607-tanzania-revives-2100-mw-hydro-power-project |access-date=3 April 2018}} The project, power station and dam are owned by and managed by the government owned Tanzania Electric Supply Company (TANESCO).{{Cite news|last=Magoum |first=Inès |date=22 April 2020 |title=Rufiji Dam infrastructure contract awarded to Elsewedy |newspaper=Afrik 21 |url=https://www.afrik21.africa/en/tanzania-rufiji-dam-infrastructure-contract-awarded-to-elsewedy/ |archive-url=https://web.archive.org/web/20200426121251/https://www.afrik21.africa/en/tanzania-rufiji-dam-infrastructure-contract-awarded-to-elsewedy/ |archive-date=26 April 2020 |url-status=live }} The power station produces 5,920 GWh of power annually.{{cite web|url=https://www.thecitizen.co.tz/news/Nyerere-dam-to-take-66-per-cent-of-energy-budget/1840340-5547042-4ywthp/index.html|title=Nyerere hydro-power dam to take 66 per cent of energy budget|work=The Citizen|date=May 9, 2020}}{{cite web|url=https://www.thecitizen.co.tz/supplement/5043016-5312004-5rapaaz/index.html|title=Nyerere Hydropower Project, honouring Mwalimu's legacy|work=The Citizen|date=October 15, 2019}}

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.{{cite book|last1=Baldus|first1=Rolf D|last2=Atanas|first2=George|editor-last=Baldus|editor-first=Rolf D|title=Wild Heart of Africa: The Selous Game Reserve in Tanzania|publisher=Rowland Ward|year=2009|isbn=978-0980262681}} It was named after him in his memory. Plans for a dam were developed during British rule of Tanganyika. Alexander Telford{{cite book|last=Hoag|first=Heather J|title=Developing the Rivers of East and West Africa: An Environmental History|publisher=Bloomsbury Academic|page=117|year=2013|isbn=978-1441155405}} conducted the first systematic development surveys of the Rufiji in 1928–1929, with engineer C. Gilman carrying out further studies in 1938–1940.{{cite book|last=Havnevik|first=Kjell J|title=Tanzania: The Limits to Development from Above|publisher=Nordic Africa Institute|year=1993|isbn=9789171063359}} 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 {{convert|100|m}} that aimed to transform the valley to an artificial environment, providing water for agriculture. The FAO's report was published in 1961 and envisaged {{convert|200,000|ha}} 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.{{cite thesis|type=PhD|last=Öhman|first=May-Britt|date=2007|title=Taming Exotic Beauties: Swedish Hydropower Constructions in Tanzania in the End of Development Assistance, 1960s-1990s.|publisher=Swedish Royal Institute of Technology}} 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.{{cite book|last=Coulson|first=Andrew|title=Tanzania: A Political Economy|publisher=Oxford University Press|year=2013|edition=2nd|isbn=978-0199679966}} The World Bank questioned the need for a dam at Stiegler's Gorge, given their calculation of limited growth in Tanzania's electricity demand.{{cite book|last=van der Straeten|first=Jonas|title=Transmitting Development Global Networks and Local Grids in the Electrification of East Africa, 1906-1970|publisher=Palgrave Macmillan}} There were also growing environmental concerns around the project, prompting the first Environmental Impact Assessment in Tanzania.{{cite journal|last1=Hoag|first1=Heather J|last2=Öhman|first2=May-Britt|year=2008|title=Turning Water into Power: Debates over the Development of Tanzania's Rufiji River Basin, 1945–1985|journal=Technology and Culture|volume=49|issue=3|pages=624–651|doi=10.1353/tech.0.0061|pmid=18831291|jstor=40061430|s2cid=27222691}} 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.{{cite book|editor-last=Usher|editor-first=Ann Danaiya|title=Dams as Aid: A Political Anatomy of Nordic Development Thinking|publisher=Routledge|year=1997|isbn=0-415-15464-2}}

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.{{cite book|last1=Kapika|first1=Joseph|last2=Eberhard|first2=Anton|title=Power-Sector Reform and Regulation in Africa: Lessons from Kenya, Tanzania, Uganda, Zambia, Namibia and Ghana|publisher=HSRC Press|year=2013|isbn=978-0796924100}} 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.{{cite report |last=Dye |first=Barnaby |date=2017 |title=The True Cost of Power: The Facts and Risks of Building the Stiegler's Gorge Hydropower Dam in the Selous Game Reserve, Tanzania |url=https://www.worldwildlife.org/publications/the-true-cost-of-power-the-facts-and-risks-of-building-stiegler-s-gorge-hydropower-dam-in-selous-game-reserve-tanzania |publisher=WWF |pages=10–35}}

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.{{cite web |url=https://www.ae-africa.com/read_article.php?NID=180 |title=Energem Enters Tanzanian Hydro-Electric Scheme |author= |date=May 2008 |website=Alternative Energy Africa}} 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.{{cite report |author=(Arms On Environment) |date=2013 |title=Situation Analysis and Report of Initial Scoping Process of the Stiegler's Gorge Hydropower Project |publisher=RUBADA}} 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.{{cite web |url=https://www.tzaffairs.org/2018/09/government-defends-stieglers-gorge-dam-project/ |title=GOVERNMENT DEFENDS STIEGLER'S GORGE DAM PROJECT |last=Taylor |first=Ben |date=1 September 2018 |publisher=Tanzanian Affairs |access-date=30 July 2019}} 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{{cite web |url=https://allafrica.com/stories/201706290490.html |title=Tanzania:JPM Snubs Stiegler's Critics

|last=Luhwago |first=Rodgers |date=29 June 2017 |publisher=Daily News Tanzania |access-date=30 July 2019}} and his interior minister threatened that opponents would be jailed in a public speech.{{cite web |url=https://www.thecitizen.co.tz/News/Anyone-against-Stiegler-s-Gorge-project-w/1840340-4575212-12u8n4f/index.html |title=Anyone against Stiegler's Gorge project will be jailed, says Minister |last=Masare |first=Alawi |date=22 May 2008 |publisher=The Citizen |access-date=30 July 2019}}

As of April 2025, all nine turbines are operational, generating 2,115 megawatts of power.{{cite news |last1=Malanga |first1=Alex |title=Julius Nyerere Hydropower project 99.55pc complete |url=https://thebizlens.co.tz/2024/12/20/julius-nyerere-hydropower-project-99-55pc-complete/ |access-date=28 December 2024 |work=The Bizlens |date=20 December 2024}}

The dam was built across the Rufiji River, at Stiegler's Gorge, in the Selous Game Reserve, Pwani Region, approximately {{convert|220|km|0}}, by road, southwest of Dar es Salaam.{{cite web|date=3 April 2018 | url=https://distancecalculator.globefeed.com/Tanzania_Distance_Result.asp?fromplace=Dar%20es%20Salaam%2C%20Tanzania&toplace=Stiegler%27s%20Gorge%2C%20Tanzania&dt1=ChIJ8dabFq5LXBgR3aGGoCZrD5Q&dt2=ChIJf7TUhESsWRgRW2Kd2-0VKZc |title=Distance between Dar es Salaam, Tanzania and Stiegler's Gorge, Tanzania |access-date=3 April 2018 | website=Globefeed.com}}

This power station is located in Selous Game Reserve, one of the world's largest World Heritage Sites, measuring {{convert|45000|km2|mi2}}. The power station and reservoir lake occupy approximately {{convert|1350|km2|mi2}}, within the game reserve.

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.{{cite web|url=https://www.reuters.com/article/us-tanzania-power/tanzania-invites-bids-for-hydropower-project-in-game-reserve-idUSKCN1BB1G5 |title=Tanzania invites bids for hydropower project in game reserve |access-date=4 April 2018 |first=Fumbuka |date=31 August 2017 | publisher=Reuters.com | last=Ng'wanakilala}}{{cite web| url=https://www.theguardian.com/environment/2017/jun/26/tanzania-presses-on-hydroelectric-dam-vast-game-reserve |title=Tanzania presses on with hydroelectric dam on vast game reserve | access-date=4 April 2018 |date=26 June 2017 |author=Bibi van der Zee |newspaper=The Guardian |location=London}} 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.{{cite web|date=30 August 2017 | url=http://www.thecitizen.co.tz/News/Tanzania-opens-bids-for-construction-of-Stiegler-s/1840340-4077020-4qow63/index.html | title=Tanzania Opens Bids for Construction of Stiegler's Gorge Project |newspaper=The Citizen (Tanzania) |access-date=4 April 2018 |author=Rosemary Mirondo |location=Dar es Slaam}} The government of Ethiopia is advising the Tanzanian government on the implementation of this project.{{cite web| url=http://allafrica.com/stories/201706280385.html | title=Tanzania: Ethiopian Experts Jet in for Stiegler's Gorge Project |access-date=4 April 2018 |date=28 June 2017 | newspaper=Tanzania Daily News |via=AllAfrica.com |location=Dar es Salaam}}

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.{{cite web |title=UNESCO reiterates its grave concern over planned dam construction within Selous Game Reserve World Heritage property (United Republic of Tanzania) |url=https://whc.unesco.org/en/news/1920/ |publisher=UNESCO |accessdate=27 June 2019 |date=12 December 2018}}

In October 2018, after diplomatic negotiations between Tanzania's President Magufuli and Egypt's President Sisi,{{cite news| title=Madbouly Affirms Egypt's Support to Development in Tanzania| publisher=Egypt Today| date=12 December 2018}}{{cite news| last=Ayah| first=Aman| title=Egypt Helps Tanzania Develop New Source of Electricity| publisher=Al-Monitor| date=18 November 2018| url=https://www.al-monitor.com/pulse/originals/2018/11/tanzania-stiegler-dam-egypt-nile-river-upstream-tension-nbi.html#ixzz5rNxDKUxN}} 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,{{Cite magazine|last=Oirere |first=Shem |date=8 November 2018 |title=Tanzania Picks Arab Contractors for Stiegler Power Project |magazine=Engineering News-Record (ENR) |url=https://www.enr.com/articles/45829-tanzania-picks-arab-contractors-for-stiegler-power-project |url-access=subscription }} at a budgeted cost of US$2.9 billion (TSh6.558 trillion).{{Cite news|last=Namkwahe |first=John |date=12 December 2018 |title=Tanzania signs contract for Steigler's Gorge major hydroelectricity project |newspaper=The Citizen | location=Dar es Salaam | url=https://www.thecitizen.co.tz/News/Tanzania-signs-contract-for-Steigler-s-Gorge-major/1840340-4892230-j10h6z/index.html |access-date=15 December 2018 }}

In February 2019, the government of Tanzania handed the construction site over to the contractors.{{Cite web|title=Serikali yakabidhi eneo la Mradi wa Umeme Mto Rufiji kwa Mkandarasi |trans-title=The government handed over the Rufiji River Power Project site to the Contractor |language=Swahili |date=February 2019 |publisher=TANESCO |url=http://www.tanesco.co.tz/index.php/media1/news-archive/325-serikali-yakabidhi-eneo-la-mradi-wa-umeme-mto-rufiji-kwa-mkandarasi |archive-url=https://web.archive.org/web/20190324063202/http://www.tanesco.co.tz/index.php/media1/news-archive/325-serikali-yakabidhi-eneo-la-mradi-wa-umeme-mto-rufiji-kwa-mkandarasi |archive-date=24 March 2019 |url-status=live |df=dmy}} Allowing several months to mobilize equipment, actual construction did not start until the summer of 2019.{{cite web| url=https://www.thecitizen.co.tz/News/All-set-for-start-of-the--3-6bn-Stiegler-s-Gorge-power-project/1840340-4983404-ybd1grz/index.html |title=All Set For Start of The Shs3.6 Billion Stiegler's Gorge Power Project |newspaper=The Citizen (Tanzania) |date=15 February 2019 |accessdate=15 February 2019 |first=Rosemary |last=Mirondo |location=Dar es Salaam}} In April 2019, the Tanzanian government made an upfront payment of US$309.645 million, representing approximately 15 percent total cost of construction.{{cite web|date=24 April 2019 | url=https://www.thecitizen.co.tz/News/Tanzania--Gov-t-issues--309-645-million-advance-payment/1840340-5086044-wr7iusz/index.html |title=Tanzania Government Issues US$309.645 Million Advance Payment To Stiegler's Gorge Contractor |access-date=25 April 2019 |newspaper=The Citizen (Tanzania) |first=John |last=Namkwahe |location=Dar es Salaam}}{{cite web |url=https://dailynews.co.tz/news/2019-04-255cc1590d84e45.aspx |title=Historic Payment For Steigler |date=24 April 2019 |newspaper=Daily News (Tanzania) |access-date=25 April 2019 |author=Lydia Shekighenda |location=Dar es Salaam |archive-date=20 November 2020 |archive-url=https://web.archive.org/web/20201120035009/https://dailynews.co.tz/news/2019-04-255cc1590d84e45.aspx |url-status=dead }}

In 2018, a new design for Stiegler's Gorge Dam was unveiled.{{cite web| url=https://dailybrief.oxan.com/Analysis/DB239911/Controversy-may-mire-Tanzanias-Stieglers-Gorge-Dam| website=Oxford Analytica Daily Brief| title=Controversy May Mire Tanzania's Stiegler's Gorge Dam|date=15 November 2018}} 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.{{cite report| title=Environmental Impact Assessment for the Stiegler's Gorge Hydropower Project, Tanzania| author=University Consultancy Bureau | publisher=TANESCO| date=4 May 2018 |url=http://www.wildlife-baldus.com/download/StieglersGorge.pdf|access-date=2019-07-31}} 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).{{cite journal| first=Barnaby| last=Dye| title=Stiegler's Gorge Dam, Tanzania| issue=Heritage Dammed: Water Infrastructure Impacts on World Heritage Sites and Free Flowing Rivers| editor-first=Eugene| editor-last=Simonov| journal=Rivers Without Borders World Heritage Watch| year=2019| url=http://www.transrivers.org/pdf/20190430%20Heritage%20Dammmed%20Report%20Draft.pdf}}

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{{cite web| title=Tanzania Country Commercial Guide| publisher=Export.Gov| date=29 January 2019| url=https://www.export.gov/article?id=Tanzania-Energy}} and 1,602 megawatts.{{cite news| title=Tanzania Eyes 10,000 MW Power Generation Capacity by 2025| publisher=Reuters| date=23 April 2019| url=https://af.reuters.com/article/investingNews/idAFKCN1RZ0SC-OZABS| archive-url=https://web.archive.org/web/20190423111923/https://af.reuters.com/article/investingNews/idAFKCN1RZ0SC-OZABS| url-status=dead| archive-date=23 April 2019}} 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.{{cite report| first=Brian| last=Cooksey| title=ITPL, Richmond and Escrow: The Price of Private Procurement in Tanzania| journal=Understanding Africa Today| publisher=African Research Institute| year=2017}}

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.{{cite news| title=Preparatory Works for Stiegler's Gorge in Good Progress| periodical=Daily News Tanzania| date=19 November 2019}}{{cite news| title=Tanzania Dam: Power Plant Planned in Selous Game Reserve| work=BBC News| date=12 December 2019| url=https://www.bbc.co.uk/news/world-africa-46539422}}{{cite journal| title=2,100-MW Stiegler's Gorge Hydropower Project Gains Further Support|date=1 August 2019| journal=HydroReview| url=https://www.hydroworld.com/articles/2019/01/tanzania-2-100-mw-stiegler-s-gorge-hydropower-project-gains-further-support.html}} The government also handed out rights to log the large reservoir area, which could bring in significant revenue.{{cite news| title=17 Tanzanian Firms Win Tenders for Logging in Hydropower Project Area in Game Reserve| publisher=Xinhua News| date=15 February 2019| url=http://www.xinhuanet.com/english/2019-02/15/c_137825299.htm| access-date=30 July 2019| archive-date=30 July 2019| archive-url=https://web.archive.org/web/20190730203027/http://www.xinhuanet.com/english/2019-02/15/c_137825299.htm| url-status=dead}}{{cite news| title=Tanzania Urged to Halt Logging Plans and Dam Project in Selous Game Reserve, as Advised by IUCN| publisher=IUCN-News| date=27 June 2019| url=https://www.iucn.org/news/iucn-42whc/201806/tanzania-urged-halt-logging-plans-and-dam-project-selous-game-reserve-advised-iucn}}

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.{{cite news| title=PM to Witness Stiegler's Gorge Dam's Contract Signing in Tanzania| publisher=Egypt Today| date=11 December 2018| url=https://www.egypttoday.com/Article/1/61754/PM-to-witness-Stiegler-s-Gorge-dam-s-contract-signing}}{{cite news| title=UPDATE 1-Tanzania to Sign Deal This Week for $3 Bln Power Plant - President| publisher=Reuters| date=11 December 2018| url=https://www.reuters.com/article/tanzania-powerstation/update-1-tanzania-to-sign-deal-this-week-for-3-bln-power-plant-president-idUSL8N1YG5LR}} 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,{{cite news| title=El Sewedy Signs $500M Loan with Afreximbank| publisher=Business Africa Online| date=13 December 2018| url=https://businessafricaonline.com/el-sewedy-signs-500m-loan-with-afreximbank/}} 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.{{cite news| title=Next Budget to Focus on Industrialisation: Gov| publisher=The Citizen Tanzania| date=14 August 2018| url=http://www.thecitizen.co.tz/News/Next-budget-to-focus-on-industrialisation--govt/1840340-4340870-wbxsulz/index.html}}{{cite news| first=John| last=Namkwahe| title=No Backing Down On Stiegler's, Govt Vows| publisher=The Citizen Tanzania| date=27 January 2019| url=https://allafrica.com/stories/201901280145.html}}

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.{{Citation needed|date=February 2021}}

The Stiegler's Gorge Dam's financial costs are contested. When Odebrecht rewrote feasibility and design studies for the dam in 2013, they estimated that it would cost £3.6 billion.{{cite report| title=Stiegler's Gorge Hydropower Project; Report and Proposal of Development| location=Grand Cayman| publisher=Odebrecht Serviços no Exterior Ltd. (OSEL) | year=2013}} The government used this figure in announcing the new design and feasibility study in 2018. However, Hartmann{{cite report| first=Joerg| last=Hartmann| title=Economic Feasibility of the Stieglerís Gorge Hydropower Project, Tanzania| publisher=OECD Watch|year=2019|url=https://www.oecdwatch.org/2019/02/14/the-true-cost-of-the-stieglers-gorge-hydropower-project-in-tanzania/}} claims the underlying costs have changed, in the price of concrete and construction costs and in engineering services. Using contemporary dam cases, he suggests that, after excluding socio-environmental mitigation, the current cost estimation should be US$7.57billion, rising to US$9.8billion if a conservative amount of overrun is factored in.{{cite journal| last=Atif| first=Ansar| title=Should We Build More Large Dams? The Actual Costs of Hydropower Megaproject Development| journal=Energy Policy| volume=69| date=June 2014|pages=43–56| doi=10.1016/j.enpol.2013.10.069| arxiv=1409.0002| s2cid=55722535}}{{cite journal| first1=Benjamin K.|last1=Sovacool| last2=Gˆtz| first2=Walter| title=Internationalizing the Political Economy of Hydroelectricity: Security, Development and Sustainability in Hydropower States| journal=Review of International Political Economy| volume=26| issue=1| date=2 January 2019|pages=49–79|doi=10.1080/09692290.2018.1511449| doi-access=free}}

Tanzania has not announced any funding agreements for the dam's construction. Given the country's economy and tax base, there are doubts about whether the government has sufficient revenue to build the dam. These are particularly relevant given specific outstanding debt issues with the electricity utility, who has signed the contracts for the Stiegler's Gorge Dam's construction.{{cite news| first1=Tausi| last1=Ally| first2=Rosemary| last2=Mirondo| title=Shift Sh1.4tr Tanesco Debt to Government, Says PIC| publisher=The Citizen|date=20 March 2019|url=https://www.thecitizen.co.tz/News/Shift-Sh1-4tr-Tanesco-debt-to-govt--says-PIC/1840340-5033700-format-xhtml-149vgwlz/index.html}}{{cite news|first=Kilasa| last=Mtambalike| title=Troubled Tanesco Risks Losing Access to Gas Pipeline| publisher=The East African| date=14 April 2018|url=https://www.theeastafrican.co.ke/business/Tanzania-tanesco-debt-gas-pipeline---/2560-4393530-47u3ycz/index.html}}{{cite news| first=Fumbuka| last=Ngíwanakilala| title=Tanzania Seeks $200m World Bank Loan to Clear Arrears of State Utility|publisher=Reuters|date=16 January 2017|url=http://www.reuters.com/article/tanzania-power-idUSL4N1F63OC|archive-url=https://web.archive.org/web/20170117033901/http://www.reuters.com/article/tanzania-power-idUSL4N1F63OC|url-status=live|archive-date=17 January 2017}} This financial situation could delay or stop payments to the contractors which would harm or derail construction.

Additional risks come from the choice of the two contractors. According to their public profiles, Dye claims that neither company has had experience of dam construction, and rather primarily builds commercial and residential buildings and transmission lines. {{Quote|text=This is deeply surprising given both companies inexperience. Arab Contractors reportedly worked on Aswan Dam in the 1960s, but would only have been one of many sub-contractors on the Russian-led project. A review of their website reveals that the company has been involved in the construction of buildings over the last decade, not on any large hydraulic or power-generation projects. Meanwhile Elsewedy appears mainly to have built transmission lines, not complex electro-mechanical systems.|author=Barnaby Dye}}

This lack of experience is notable given the size of Stiegler's Gorge Dam and the degree of hydrological flux in the Rufiji River. There has not been a supervising, 'owner's engineer' appointed to ensure the quality of construction.

This contracting arrangement and the appointed companies entail important risks. Some of these are technical, concerning the construction of a project that stands up and functions (producing electricity) for the intended 50 years. This will depend on the accuracy and rigour of hydrology, sediment, climatic and hydropower studies and the engineers' ability to accurately implement complex designs. There would also be a project management issue in undertaking infrastructure on this scale with recruitment estimated at 4000 plus personnel and a number of sub-contractors. Neither company appears to have experience of management on this scale. In its most extreme sense, this raises questions about dam safety, both in the construction phases and in the end product. A number of dam collapses such as the St. Francis Dam (USA) or Malpasset Dam (France) stemmed from poor studies and insufficient engineering standards.{{Citation needed|date=February 2021}}

Another risk concerns environmental and social impacts. Given inexperience, the companies are unlikely to be familiar with mitigation codes of practice that could limit impacts, e.g. stopping dumping of soil in the river or in handling waste. There are also concerns over dam safety for workers, given the long history of accidents on dam projects before extra industry efforts in the 21st century.{{cite book| title=Past African cases of worker deaths during construction include: Cahora Basa Dam Allen F. Isaacman and Barbara Isaacman, Dams, Displacement, and the Delusion of Development: Cahora Bassa and Its Legacies in Mozambique, 1965/2007 New African Histories| publisher=Ohio University Press| year=2013}}{{cite book| first=Julia| last=Tischler| title=Light and Power for a Multiracial Nation: The Kariba Dam Scheme in the Central African Federation| location=Basingstoke, Hampshire| publisher=Palgrave Macmillan| year=2013}}{{cite journal| first=Barnaby| last=Dye| title=The Return of ìHigh Modernismî? Exploring the Changing Development Paradigm through a Rwandan Case Study of Dam Construction| journal=Journal of Eastern African Studies| volume=10| issue=2| date=2 April 2016| pages=303–324| doi=10.1080/17531055.2016.1181411| s2cid=147971438}}

There are also significant concerns over poaching which has been a longstanding issue in the Selous Game Reserve.{{cite report| title=Reactive Monitoring Mission Selous Game Reserve (United Republic of Tanzania), 02 - 11 December 2013 |author=Tilman Jaeger |author2=Guy Debonnet |author3=Nelson Guma | publisher=UNESCO World Heritage Centre - IUCN | date=January 2014|url=https://whc.unesco.org/en/documents/129161/|access-date=2019-07-31}} Poaching was the primary reason for placing the UNESCO World Heritage Selous Game Reserve on a list of endangered sites.{{cite report| title=Convention Concerning the Protection of the World Cultural and Natural Heritage| year=2013| url=https://whc.unesco.org/archive/2013/whc13-37com-20-en.pdf}} The increased presence of people and steady flow of construction traffic, as well as logging camps, provides substantive opportunities for poaching and smuggling, especially if the companies do not have know-how to enforce anti-poaching measures.{{cite report| title=UNESCO Expresses Concern over the State of Conservation of Selous Game Reserve| journal=Official World Heritage Committee Communication| date=22 February 2018| url=https://whc.unesco.org/en/news/1785}} Thus, the choice of the contractors magnify the pre-existing risks of undertaking the Stiegler's Gorge project.

There are a number of risks to the effective functioning of the Stiegler's Gorge Hydropower Project, if it is completed. One of these comes from climate change. It is unclear if the total rainfall in Tanzania will increase or decrease, but studies suggest that precipitation's variability will increase.{{cite journal|first=Declan|last=Conway|display-authors=etal| title=Climate and Southern Africaís Water–Energy–Food Nexus| journal=Nature Climate Change| volume=5|issue=9 | date=21 August 2015|pages=837–846| doi=10.1038/nclimate2735|bibcode=2015NatCC...5..837C|hdl=10568/68001|url=http://eprints.lse.ac.uk/63308/1/Conway_Climate%20and%20southern%20Africa%27s%20water.pdf|hdl-access=free}}{{cite journal|first=Declan|last=Conway|display-authors=etal| title=Hydropower Plans in Eastern and Southern Africa Increase Risk of Concurrent Climate-Related Electricity Supply Disruption| journal=Nature Energy| volume=2|issue=12| date=1 December 2017|pages=946–953|doi=10.1038/s41560-017-0037-4|bibcode=2017NatEn...2..946C|s2cid=12895244|url=http://eprints.lse.ac.uk/86348/1/Conway_Hydropower%20plans_2017.pdf}} This is important as it will affect hydropower production, decreasing the dam's electricity-generation reliability. This is particularly important in the context of hydro-dependency. Tanzania gets the majority of its electricity from hydropower. A failure in these dams in the dry season is the key reason for the country's power failures, which happen frequently.{{cite report| title=Program Document on a Proposed Development Policy Credit For a Second Power and Gas Sector Development Policy Operation| journal=Eastern Africa Country Cluster 1, AFCE1 Africa Region |location=Washington, D.C.| publisher=The World Bank| year=2014}}{{cite report| title=Program Document on a Proposed Development Policy Credit For a First Power and Gas Sector Development Policy Operation| journal=Eastern Africa Country Cluster 1, AFCE1 Africa Region| location=Washington, D.C.| publisher=The World Bank|year=2013}} This vulnerability will increase if the Stiegler's Gorge Dam is completed. If brought online today, a failure of the Stiegler's Gorge Hydropower Plant would reduce power production by 58.3%.

The other risk comes from sedimentation. A report highlighted the vulnerability of the reservoir to rapid sedimentation. This is because of the existing sediment load in the Rufiji River and the high levels of erosion likely to occur around the reservoir. Higher sedimentation would decrease the reservoir's capacity to store water. Such a reduction would reduce the reliability of the reservoir, as it would make it more directly dependent on precipitation.

Another fiscal danger comes from the ability of Tanzania's electricity utility, TANESCO, to sell the hydro-plant's energy. Given Tanzania's current peak capacity of around 1.05 GW and installed capacity of 1.5 GW, there are persistent doubts about whether Tanzania can sell the dam's energy. A number of reports cast doubt on the ability of the Tanzanian economy and electrification schemes to absorb the dam's demand.{{cite report| first=Joerg| last=Hartmann| title=Economic Feasibility of the Stieglerís Gorge Hydropower Project, Tanzania| location=Amsterdam, Netherlands| publisher=OECD Watch| year=2019| url=https://www.oecdwatch.org/2019/02/14/the-true-cost-of-the-stieglers-gorge-hydropower-project-in-tanzania}} Without such sales, the government will not easily recoup their investment. These reports also suggest that selling to the regional grid, to neighbouring countries through the Southern and Eastern African Power Pools, is unlikely to work given that both trading schemes are insufficiently institutionalised. There also appears to be a high level of distrust between countries when it comes to relying on others for power.{{Citation needed|date=February 2021}}

Academics and consultants have established the Stiegler's Gorge Dam's impacts. They have argued that the significant level of environmental and social effects constitute an important trade-off in pursuing Stiegler's Gorge Dam.

The key controversy of the proposed Stiegler's Gorge project concerns its environmental impacts. An obvious concern is the location of the gorge in the middle of the Selous Game Reserve World Heritage Site. Firstly, the dam will flood over 2.2% of the reserve's total area, roughly equivalent to the size of Andorra, reducing its forest and riverine habitat.{{cite report| last=Havnevik| first=Kjell J| title=Tanzania: The Limits to Development from Above| location=Dar es Salaam Tanzania Nordiska Afrikainstitutet| publisher=Mkuki na Nyota Publishers| year=1993}}{{cite journal| first1=Stéphanie| last1=Duvail| first2=Olivier| last2=Hamerlynck| title=The Rufiji River Flood: Plague or Blessing?| journal=International Journal of Biometeorology| volume=52| issue=1| date=10 October 2007| pages=33–42| doi=10.1007/s00484-007-0105-8| pmid=17562084| bibcode=2007IJBm...52...33D| s2cid=38904808}}

Additionally, the dam project would be directly above the main area of biodiversity in the reserve. This consists of a large wetland, marsh and savanna area. The Rufiji River plays a central role in creating this environment. In the wet season, this river has a particularly strong hydrological surge. This force of water during the wet season changes the Rufiji River's path, creating a shifting pattern of oxbow lakes, dried river channels and wetland. Collectively this creates a rich habitat contrasting with surrounding dry savannah.{{cite journal| first=Raphael B. B.| last=Mwalyosi| title=Environmental Impacts of the Proposed Stieglerís Gorge Hydropower Project, Tanzania|journal=Environmental Conservation| volume=15|issue=3|date=September 1988|pages=250–254| doi=10.1017/S0376892900029398| s2cid=86760666}}

The Rufiji River has a strong seasonal variation. In the wet season, it floods a large area of land, irrigating the soil and spreading nutrient sediments. The wet season also refills and connects lakes in the Selous Reserve.

Building a dam will change this seasonal river pattern and withhold sediment. It will create a more constant hydrological discharge, reducing the wet season flood. This will undermine the ecological irrigating and fertilising services of the river. The Stiegler's Gorge Dam will therefore harm the wetland areas of the Selous and the wide variety of mammal and bird life that use it, including numerous waders, storks and herons as well as hippo and crocodiles. Large, land-based mammals from elephants to lions also benefit from the presence of the water, particularly in the dry season.

The Selous contains a number of endangered species, including lion, Sanje crested Mangaby, wetland crane, lesser kestrel, Udzungwa red colobus monkey, Udzungwa forest partridge and rufous-winged partridge. Impact assessments indicate these could be affected by a future project.{{cite report| title=Situation Analysis Report of Initial Scoping Process of the Stieglerís Gorge Hydropower Project| publisher=OSEL Odebrecht Servicos no Exterior| location=Dar es Salaam, Tanzania| author=(Arms on Environment)| year=2015}}{{cite journal| first=Olivier| last=Hamerlynck| display-authors=etal | title=To Connect or Not to Connect? Floods, Fisheries and Livelihoods in the Lower Rufiji Floodplain Lakes, Tanzania| journal=Hydrological Sciences Journal| volume=56| issue=8| date=December 2011| pages=1436–1451| doi=10.1080/02626667.2011.630002|doi-access=free}}

The dam will mean that downstream oxbow lakes are cut-off, become more saline from evaporation and will reduce in size. Cutting-off the lakes will also prevent the regeneration of fish stocks, particularly migratory fish. A study by Duvail et al. found that these negative impacts would occur even with a mitigating flood release of 2,500cms.{{cite journal| first=Stéphanie| last=Duvail| display-authors=etal| title=Jointly Thinking the Post-Dam Future: Exchange of Local and Scientific Knowledge on the Lakes of the Lower Rufiji, Tanzania| journal=Hydrological Sciences Journal| volume=59| issue=3–4| date=March 2014| pages=713–730| doi=10.1080/02626667.2013.827792| s2cid=129576155|doi-access=}} For instance, this proposed water release would end at least two of the downstream lakes.

Below the Selous Game Reserve is the Rufiji River Delta. This delta area, including Mafia Island, is protected by the highest international level of wetland protection, called the Ramsar Convention. The ecology of this area also depends on the river's seasonal nature.{{cite conference| first=Raphael B. B. | last=Mwalyosi| title=Management of the Rufiji: Delta as a Wetland| book-title=Wetlands of Tanzania| conference =Seminar on the Wetlands of Tanzania| location=Morogoro, Tanzania| year=1991}} The wet season's river-water surge counteracts the saline sea, maintaining a balance of salinity in the delta that underpins its current plant and animal mix. This salinity balance supports the largest mangrove stand in East Africa.{{cite journal| first1=Ian| last1=Brown| first2=Simon| last2=Mwansasu| first3=Lars-Ove| last3=Westerberg| title=L-Band Polarimetric Target Decomposition of Mangroves of the Rufiji Delta, Tanzania| journal=Remote Sensing| volume=8| issue=2| date=9 February 2016|pages=140| doi=10.3390/rs8020140| bibcode=2016RemS....8..140B| doi-access=free}}

The river's wet season surge, because it brings a large volume of fertile sediments, also supports an algal bloom in the ocean delta. This bloom spawns a rapid annual explosion in plankton, which in-turn supports a rapid increase in fish. Migratory whale sharks and other animals also visit the delta area in the wet season to specifically take advantage of this bloom.

By altering the river's flow and withholding sediment, the dam will therefore damage the UNESCO Selous Site, downstream lakes and the Ramsar-protected delta area.

Impacts on the environment will have important socio-economic effects. The river's annual irrigating and fertilising flood creates a rich area of farmland below the park. Typically, this supports recession agriculture that takes place in the dry season. Indeed, the Rufiji valley contains some of Tanzania's richest farmland, including extensive paddy fields. People living in the valley also utilise lakes which are replenished by annual floods. These lakes provide a source for irrigation and a useful fish stock. Therefore, a change caused by the dam will negatively impact people's livelihoods downstream.

Another key impact is on fishing in the Rufiji River delta. This area is Tanzania's economically richest fishery, centred on prawns. Prawns and other fish numbers are underpinned by the river's wet season pulse. Building the Stiegler's Gorge Dam will therefore harm fisheries around the Rufiji delta.

Another direct impact of the dam will be on tourism. This will be twofold. The main photo-tourist area of the Selous is the part of the reserve immediately below the gorge. The remainder of the park is for hunting tourism and will be negatively affected by construction. The building of the dam will bring a visual impact on this area because of the improved roads and large number of vehicles transporting materials to the dam. The hydropower plant will also require transmission lines. The Beho Beho Hills will visually shield the dam itself. Regardless, the short and long-term negative impacts on the wildlife of the park will undermine the reason for hunting and photo tourism.

Particularly large Rufiji floods can significantly damage the communities living along the Rufiji River. This happened in 1968 for instance when floods destroyed crops, houses and infrastructure. However, research demonstrates that many people living in the valley value such large floods, seeing them as a blessing in the longer term, not a plague. This is because of a perception of the floods as agriculturally important. Floodwater spreads more sediment creating rich agricultural conditions in for the following years.

On the other hand, the project is expected to provide employment opportunities and invaluable experience to many Tanzanian engineers.{{Citation needed|date=February 2021}}

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• List of power stations in Tanzania
• Eastern Africa Power Pool
• Southern African Power Pool

{{Reflist}}

• [http://www.diva-portal.org/smash/record.jsf?pid=diva2:12267 Taming Exotic Beauties: Swedish Hydro Power Constructions in Tanzania in the Era of Development Assistance, 1960s - 1990s], Stockholm, 2007, PhD Thesis, by Öhman, May-Britt.

• [http://www.tanesco.co.tz/ Official Website of Tanesco]
• [https://www.hydroworld.com/articles/2017/06/tanzania-s-stalled-2-100-mw-stieglers-gorge-hydropower-project-could-have-new-life.html 2,100-MW Stieglers Gorge hydropower project could have new life] As of 21 June 2017.
• [https://www.wwf.de/fileadmin/fm-wwf/Publikationen-PDF/WWF-Report-Selous-True-Cost-Of-Power.pdf WWF-Report: The true cost of power], June 2017 (critical evaluation of the project)
• [https://www.cambridge.org/core/journals/environmental-conservation/article/environmental-impacts-of-the-proposed-stieglers-gorge-hydropower-project-tanzania/5C06F6165883FAA72BC6538B8D35DEE2 Environmental Impacts of the Proposed Stiegler's Gorge Hydropower Project, Tanzania] As of 1 August 2009.

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