Lake Mangamahoe, lake in New Zealand

Lake Mangamahoe is a man-made reservoir in the Taranaki region, situated south of New Plymouth. The water is fed by streams and the Waiwhakaiho River, and the surroundings consist of extensive pine forests with pockets of native bush and regenerating woodland.

Lake Mangamahoe's dam was planned after New Plymouth's electric tramway began operating in 1915, when it became clear the town would face an electricity shortage. The dam was completed in 1931, and from the outset the water was intended both for power generation and as a drinking-water reservoir. Water diverted from the Waiwhakaiho River through a pipeline helps fill the lake, and a pipeline at its northern end carries water about 1.5 km to a hydroelectric power station producing part of New Plymouth's electricity.

The name Mangamahoe comes from te reo Māori. The reservoir was planned from 1915, when New Plymouth's electric tramway opened and the town faced a power shortage, and it was built to serve both electricity generation and drinking water. Water is drawn from the Waiwhakaiho River through a pipeline to fill the lake.

The site is easily accessible with parking, toilet facilities, and picnic areas near the main entrance. Well-marked trails suited to different fitness levels wind around the lake, though some sections can become muddy after rain, so sturdy footwear is advisable.

The dam was planned after New Plymouth's electric tramway opened in 1915, when the city foresaw a power shortage; the finished dam dates from 1931. Water is drawn from the Waiwhakaiho River through a pipeline to fill the reservoir, and a second pipeline at the northern end carries water about 1.5 km to a power station.