Lake Rotorangi was formed in 1984 as a reservoir for hydroelectric power.

The lake was formed by building an 80-metre high earth wall dam near the end of Ball Road in South Taranaki District.

The dam created then filled the Patea River valley for a distance of about 46 kilometres to make the longest reservoir of its type in New Zealand.

The Pātea Dam is owned by Manawa Energy (formerly Trust Power) and rated at 33 MW output (115 GWh per annum).

It is also a public camping ground, used in the summer time for various water sports.