In March 1949 the government committed to building at Tamblyn's Orchard and plans were prepared to enable work on the diversion channel to start in June 1949. In October 1949 at the request of the Ministry of Works, Dr. John L. Savage - a former Chief Design Engineer of the United States Bureau of Reclamation - visited the site and provided advice on the proposed design options. While an earth dam was more suitable at the wider Pleasant Valley location after considering various options it was decided in October 1950 that due to the geology at Tamblyn's Orchard a solid-concrete gravity dam would be more appropriate. Another consideration was that the Ministry of Works and Development (MOW) had limited experience with the construction of earthen dams and its only engineers with the necessary experience were engaged on the Cobb Power Station.