The purpose of the rehabilitation works included increasing the water storage capacity of the reservoir by 55% and improving spillway discharge potential to meet the new 1:100,000 AEP flood requirements.

The project challenges, mainly due to the presence of high tailwater level right downstream of the Fusegates and highly perturbed approach channel conditions at the spillway, required a detailed physical scale model analysis in order to optimize the design, reduce the cost and minimize the risks.