[1] The lake has a maximum length of 12 kilometres (7.5 mi), and lies on the western side of Maungatua, above and to the west of the Berwick Forest.

[2] However, there was no storage built into the original scheme, and in the first year of operation, low flows in the river led to constraints on the generating capacity.

Between 1907 and 1913, some storage lakes were created on tributaries, including an early concrete arch dam on Pioneer Creek.

In 1920, the Dunedin City Corporation Empowering Act was successfully pushed through Parliament, against opposition from mining interests, to enable the use of the Waipori River as a hydro-electric reservoir.

Lake Mahinerangi was formed by this new 20.4-metre (67 ft) high dam, and an additional powerhouse of 3,000 kilowatts (4,000 hp) capacity was commissioned.

[4] The Waipori hydro-electric scheme includes a network of four dams and power stations and produces a maximum output of 84 megawatts (113,000 hp).