This included a far larger dam wall of around 100 metres (330 ft) that aimed to transform the valley to an artificial environment, providing water for agriculture.

[9] 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.

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.

[9] By the 1970s, the Norwegian NORAD development agency had taken on the Stiegler's Gorge Planning, producing detailed feasibility and construction designs.

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.

[12] The World Bank questioned the need for a dam at Stiegler's Gorge, given their calculation of limited growth in Tanzania's electricity demand.

[16] 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 decision gave renewed purpose to Rubada, the agency tasked with implementing the dam, who started actively lobbying for the project and meeting companies.

Magufuli has been vocal in denouncing any critics of the dam[21] and his interior minister threatened that opponents would be jailed in a public speech.

[23] The dam is being built across the Rufiji River, at Stiegler's Gorge, in the Selous Game Reserve, Pwani Region, approximately 220 kilometres (137 mi), by road, southwest of Dar es Salaam.

The power station and reservoir lake are planned to occupy approximately 1,350 square kilometres (520 sq mi), within the game reserve.

[28] In October 2018, after diplomatic negotiations between Tanzania's President Magufuli and Egypt's President Sisi,[29][30] 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,[31] at a budgeted cost of US$2.9 billion (TSh6.558 trillion).

[1][34] In April 2019, the Tanzanian government made an upfront payment of US$309.645 million, representing approximately 15 percent total cost of construction.

[41] The Stiegler's Gorge Hydropower Project will therefore significantly increase the installed capacity on-grid in Tanzania, supporting power for industrialisation and electrification.

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.

[46][47] 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.

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.

[37] 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.

[39]This lack of experience is notable given the size of Stiegler's Gorge Dam and the degree of hydrological flux in the Rufiji River.

This will depend on the accuracy and rigour of hydrology, sediment, climatic and hydropower studies and the engineers' ability to accurately implement complex designs.

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.

[63] Poaching was the primary reason for placing the UNESCO World Heritage Selous Game Reserve on a list of endangered sites.

[64] 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 knowhow to enforce anti-poaching measures.

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.

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

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.

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.

[78] The river's wet season surge, because it brings a large volume of fertile sediments, also supports an algal bloom in the ocean delta.

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.