The River Derwent begins its journey at Lake St Clair and flows in a south-easterly direction. It reaches sea level and becomes an estuary between New Norfolk and Granton. The harnessing of the hydro-electric potential of the catchment area began in 1934 and the last power station was commissioned in 1968. It involved a series of separate developments and included the construction of 16 dams, 10 power stations and a large number of weirs (small dams), flumes, canals, tunnel and pipelines.