Dr. Sean Avery of the Water Resource Associates conducted a study of the Hydrological Impact of Gibe III on Lake Turkana's Water Levels and Fisheries and published a report in November 2010. The report finds major problems with the construction and commissioning of the dam, including
- As Lake Turkana is dependant on the Omo River for almost 90% of its inflow, this river is the lake’s “umbilical cord”. If the Omo River inflow is reduced, the lake level and associated biomass will fall. If the Omo river flow patterns are modified, the lake ecology will be impacted. The lake is almost entirely within Kenya, whereas the Omo River is entirely within Ethiopia. Hence management of the Omo Basin and lake water resources presents trans-boundary challenges.
- Developments within the Omo Basin will impact the fisheries resources of Lake Turkana. The fish resources are known to decline with flow reductions. The fish resources are also known to depend on seasonal flood-plain inundations that result from natural flood inflows. The proposed regulated Omo flows will alter the flood inflow patterns upon which the lake fish depend, and will alter the transport of nutrients.
- Developments within the Omo Basin, which remove water for consumptive use, especially through irrigation abstraction, will impact the lake through reduced inflows and a reduction in lake levels, and associated with this, there will be a reduction in the water table. The filling of the Gibe III reservoir will cause a two-metre drop in Lake Turkana’s level. Thereafter, the dam alone will not alter the annual water volume inflow volume, except insofar as losses that occur within the Gibe III reservoir. Hence, as long as reservoir losses are proved minimal, once filled, Gibe III alone will not cause lake levels to fall.
- The real challenge to lake levels lies with other consumptive use projects within the Omo Basin, namely extensive irrigation development, which is independent of Gibe III. If the lake level falls, biomass reduces and the fish population falls.