Onehunga - Geography

Geography

Onehunga is slightly unusual in that it has a substantial underground freshwater source, the Onehunga aquifer, which it owes to rainwater soaking through the lava flows around One Tree Hill. While most of drinking water of the Auckland area is drawn from reservoirs in the Hunua and Waitakere Ranges, around 5% is drawn from the Onehunga aquifer. The up to 20,000 m³ that are daily drawn from the source receive treatment in a local plant before being fed into the freshwater supply network. In contrast, while the waters of Western Springs also seep through the city's lava fields, they are no longer used as a source of drinking water.

The port area of Onehunga is now much smaller than Auckland's east coast port on the Waitemata Harbour, although in the 19th century it was the larger. The wharves are located on reclaimed land bordering a low volcanic crater called 'Hopua', once occupied by a tidal lagoon opening to the southwest, but which was also reclaimed.

Onehunga's southwestern side, near the Mangere Harbour, lost its direct waterfront access in the 1970s, when the Southwest Motorway was built there. Only a tidal lagoon remains on the city side, though as of 2008, there are proposals that the motorway (which is to be widened further) could be sunk into a trench to provide direct access to the harbour again.