French engineering, design and project management firm Artelia has been picked to replace Deltares—an independent Dutch institute for applied research in water and subsurface—in a contract to study the impact of the $4 billion Great Ethiopia Renaissance Dam (GERD) on the flow of the Nile River.

The Tripartite National Committee (TNC) of Sudan, Egypt and Ethiopia selected Artelia on Dec. 29 after a three-day meeting in Sudan’s capital Khartoum attended by water and foreign ministers from the three countries.

Artelia will now partner with another French firm, BRL Ingenierie (BRLi), a subsidiary of BRL Group, in carrying out technical studies on the potential impacts of GERD on the flow of the Nile, particularly on downstream countries Egypt and Sudan. The dam, which also is expected to generate 6000 MW of electricity for export, is being constructed on the Blue Nile by Italian construction company Salini Impregilo SpA.

In September, Deltares pulled out of the study contract. In a statement, Deltares said: “After three months of negotiations on possible cooperation for the studies with BRLi…Deltares had to conclude that the conditions imposed by the TNC and BRLi on how the studies should be carried out did not provide guarantees for Deltares that an independent high-quality study could be carried out.” Deltares did not elaborate on what the “conditions” were.

The dam is in Ethiopia, source of 85% of the Nile River’s water, 20 km upstream of its border with Sudan. The project involves construction of a 145-m-high roller-compacted dam with a 74-billion-cubic-meter capacity reservoir, but with an estimated active total storage of 59.2 billion cubic meters. The reservoir will cover an area of 1,874 km². A 5-km-long, 50-m-high saddle rockfill dam with bituminous surface sealing is also being constructed. Some analysts warn that it may take up to seven years to fill the reservoir, with negative consequences to downstream countries—particularly Egypt.

It is not clear why the study by the two French firms will be important since the dam is reportedly more than 60% complete. Motuma Mekasa, the Ethiopia minister for water resources and energy, said in December, “the construction works of the dam project are ongoing and will not stop.”

In May 2015, the three countries signed a ‘Declaration of Principles’; a 10-point document that outlined the role of Ethiopia, Egypt and Sudan in ending a four-year dispute in the sharing of the Nile water. Egypt, which gets a quota of 55.5 billion cubic meters of the Nile water—an equivalent of more than 90% of its water needs—has raised concerns on the impact of the project on the country’s water security.

The Artelia-BRLi study will be the second in three years. An earlier one by a 10-member “International Panel of Experts” was submitted to the three governments in May 2013. With no known studies about the dam’s impact on Nile River’s flow to reference, the experts relied on vetted documents supplied by the Ethiopian government, in addition to at least four site visits.

The experts’ report says Ethiopia’s document on the project’s hydrological study “is very basic and not yet at a level of detail, sophistication and reliability that would befit a development of this magnitude, importance and with such regional impact as GERD.”

The team also said the original design of the dam was altered “due to various new hydrological, geological and geotechnical findings,” but no details have been provided to explain reasons for the change of the dam’s design or that of project components such as the saddle dam, seepage control and the spillways.

“The stability of the main dam and other structures should be verified under construction of the additional geological and geotechnical findings,” the report noted.

The experts warned that with the construction of GERD’s reservoir, power generation at Egypt’s High Aswan Dam downstream could drop by 6% “due to the general lower water levels in Lake Nasser.”

“Should the filling [of the reservoir] occur during dry periods, the High Aswan Dam will reach minimum operating level during at least four consecutive years, which would significantly impact on water supply to Egypt and cause of loss of power generation at High Aswan Dan for extended periods,” the report states.

International Rivers, an NGO for the protection of rivers, also says the massive reservoir will evaporate an estimated 3 billion cubic meters of water per year, “three times Egypt’s annual rainfall and enough to meet the basic needs of up to 500,000 people.”

Egypt said in December it is “satisfied” with the outcome of the Khartoum meeting and expressed optimism that the country will have a “strategic partnership” with Ethiopia and Sudan.

Ethiopia’s Foreign minister Tedros Adhanom said in a statement in December that the agreement on Artelia as a replacement for Deltares showed progress on ongoing negotiations over GERD, which he said “will be useful to the three countries.”