Isimba dam spillway repairs estimated at sh551b

The government has committed to repairing Isimba Hydropower Dam in Kayunga District to full capacity without affecting electricity supply.

State Minister for Energy Sidronius Okasai made the announcement on March 5, 2025, during a press briefing at Parliament.

His statement was in response to concerns that were recently raised by lawmakers on the natural resources committee touching on the structural defects at the vital national asset.

During an oversight visit, MPs uncovered weaknesses in the dam’s main spillway and embankments, raising fears over its long-term stability.  

The briefing brought together key stakeholders, including Natural Resources Committee Chairperson Herbert Edmund Ariko, Prof. Wang Yongtian the Vice President of China International Water and Electric Corporation (CIWE) the contractor responsible for the project.

Others present included Dr. Eng. Badru Kiggundu the chairperson of the Karuma and Isimba Hydropower Projects Steering Committees, Eng. Dr. Harrison Mutikanga, CEO of Uganda Electricity Generation Company Limited (UEGCL), and Marc Davies, the Resident Project Manager.

The engagement aimed to chart a way forward in addressing the defects. The dam, commissioned in 2019 as part of the country’s push for energy self-sufficiency, is a key component of Uganda’s power grid, making its restoration a priority for the government.

Rehabilitation cost

“The physical repair or construction of a new spillway will cost not less than $50million. That’s not the only cost we talked about, maintenance insurance is calculated at about $90m, then the insurance of the spillway itself has to be determined. When you put this all together, it is not anything less than $150m (sh551.2b). Those are working figures.
They will either go up or go down because we are going to rely on the tests which are going to be done,” Okasai hinted.

“At an appropriate time, we shall come to tell the country what the repairs of the dam are going to cost and that money has to be mobilized. Initially it is at the cost of the contractor (CIWE),” he added.

Prof. Wang, the vice president of CIWE, assured “For us we will continue to take action and work closely with Parliament committees, UEGCL and CIWE and try to complete the repair of these defects and complete the works as quickly as possible.”

Broader environmental impact

While the primary focus is on the spillway, State Minister for Energy Sidronius Okasai emphasized that the government is also assessing the integrity of other components, such as the buffer wall, and evaluating the broader environmental impact.

“Karuma, anything that happens on this dam will also affect it. Anything that affects this dam will also affect the dams upstream which include Bujagali, Kiira, Nalubaale and it would also affect the lake (Victoria). So, we are also looking at the total value chain of electricity generation on the River Nile. We have plans to develop other dams downstream, all are considered in the discussions,” he explained.

PMT test

While some observers have suggested that the serious issues with a dam commissioned just six years ago must be due to poor workmanship, Eng. Badru Kiggundu said it is too early to make conclusions.

“Structural systems are subject to live the design life or sometimes they might come short. This one has come very short in its design life. This is why we are going through this Physical Model Test (PMT)test which will prescribe and evolve to some of the reasons and we shall be reporting back to you as a county. We are also equally concerned. As close as we are to the project on why it has come this early. So, be patient,” he urged. 

Fast forward, Herbert Edmund Ariko, Chairperson of the Natural Resources Committee (Soroti East, NRM), anticipates a delegation of UEGCL, MEMD, and a panel of experts to witness the PMT in Nanjing, China, by the end of this month. Following this, the necessary remedies will be deployed.

 “The contractor is going to create a demo of a spillway to which pressure is going to be applied as though River Nile flows. That model is going to be mirrored on what we expect to be our spillway. When the material members of the spillway are subjected, it will help determine whether or not, the material which was used for the construction of the spillway could withstand the pressures of water, in what capacity and for what period,” Ariko explained.

Henceforth, the technical team has been tasked with urgently assessing the situation to determine the required technical solutions for ensuring dry conditions for inspection and effective repairs by mid-month.

“Currently, inspections being undertaken are either through gadgets of technology or diving underwater. So, the images which are captured are sometimes blurred or impaired by the conditions of water,” he added. 

His talking points were based on resolutions reached during a meeting yesterday involving the government, the contractor, and the committee among others.

No cause for alarm:

Addressing journalists on Wednesday, UEGCL’s CEO, Eng. Dr. Harrison Mutikanga, dismissed alarmist claims.

“Isimba is not falling apart. We are generating electricity; I think since we started commercial operations in 2019, we are contributing on a daily basis about 183 Mega Watts (MW) to the national grid and we have since generated over $200million (equivalent to sh753billion).

We are servicing our debt (sh2trillion) timely. So, the challenge we got on a spillway, like on all large projects, these things happen but the important thing is that we are addressing the challenges we have got. The answer is yes,” Mutikanga affirmed.