The Waipori River is located about 64 km to the west of Dunedin, rising in the Lammerlaw Mountains. After winding through a course of about 24 km the River emerges into a valley 1.5 km wide and 27 km long, with a drop of only 30-metres.

The valley outlet is a narrow gorge which sharply drops 165-metres over only 4 km. The Waipori River joins the Taieri River near Henley, 30 km southwest of Dunedin.

It is this natural river flow, which rushes down the steep slopes of mountain ranges, roams through a relatively level plateau, before rushing through a rocky gorge, which makes this natural resource the ideal setting for generating hydro-electricity. The river’s level plateau provides the perfect setting for the scheme’s storage facility (Lake Mahinerangi) while the steep, narrow gorge provides the fall necessary for the water to drive the turbines.

The name Waipori means “Dark Water” in Maori.  This is appropriate because the water is often muddy as it is stained by the peat in the swamps at the head of the river.

Following the first steps towards generating electricity from the Waipori River in May 1900, on 27th April 1907 the Waipori Hydro-Electric Power Station was commissioned.

The water was diverted out of the Waipori River by a 3-metre timber crib dam and conveyed for about 2.7 km in a wooden flume, constructed of locally sourced timber, 6 feet wide and 4 feet deep.  The power station contained two 1,000kW 2400 volt three phase generators driven by Pelton Wheels, operating under a head of approximately 206-metres.

The electricity generated was transmitted to the Halfway Bush Substation via two 33kV lines and two 3.3kV lines were constructed to distribute power throughout the city.

As a result of progressive development, the Waipori Hydro Scheme today consists of four generation stations. Waipori 1A delivers 10 MW, and Waipori 2A, 3 and 4 deliver 58 MW, 7.6 MW and 8 MW respectively.

The scheme has a total average annual output of 192 GWh. 

While supporting a valued sports fishery, Lake Mahinerangi is also recognised as possessing areas of reasonably high amenity value. Downstream of the Lake, the Waipori River provides a valuable in-stream habitat for a number of native and exotic fish species.

In 2003, the scheme was granted the Resource Consents necessary to allow its continued operation for a further 35 years.