The Clutha River is fed from Lake Hāwea, Lake Wakatipu, and Lake Wānaka. There were already existing control gates on the Kawarau River at the outlet of Lake Wakatipu and it was decided to control the flows from the remaining lakes. After investigation found that the soil conditions were unsuitable at Lake Wanaka only Lake Hāwea received new control structure. This was commissioned in 1958 and consists of four radial gates housed in an earth dam. The dam raised the existing lake level and currently provides approximately 290 GWh of storage.