Mangatangi Reservoir

Mangatangi Dam is the largest water supply reservoir of Auckland city with a storage volume of 39 million m3. Dam's crest length is 340m, with a height of 80m and the reservoir area covering 169ha of land. This reservoir was the last of earth dams to be completed in Auckland's water supply projects in the Hunua Ranges and is one of New Zealand's largest dams. With a capacity of 39 million cubic metres, it supplies nearly a quarter of the city’s water demand through a large treatment plant in Clevedon. The project planning started in 1969 and construction was completed in 1977. Construction was delayed by series of events such as earth slips, foundation and excavation difficulties, labour shortages and contractor management lapses.