When driving down Woodlands park road from Scenic Drive, you might have noticed what looks to be a very expensive footpath. It turns out it’s actually the historic Huia Aqueduct (or conduit), built in the 1920s, but still supplying all the water that feeds into the Huia Water Treatment Plant.
The aqueduct was the idea of Arthur Mead, later city Waterworks Engineer for many years. Early on in his career he was sent into the Waitakere Ranges to work on the surveying and design of the Upper Huia and Upper Nihotupu dams. He came up with the idea of an aqueduct that would run all the way from Piha, south to Whatipu and Huia and then into the city, collecting water from all the streams along the way.
This never went ahead as his supervisors decided that it was better to focus on the bigger supply that the Hunua scheme would eventually bring. A couple of short sections were built at the time of construction of the Upper Huia Dam. The Huia Tunnel Aqueduct runs 1200m between the Huia and Nihotupu valleys. The Huia Conduit is a 2.4km reinforced concrete box structure that is partly tunneled and partly above ground – including some bridged sections to cross streams.
The route of the conduit section is through private property and the Waitakere Ranges just below Exhibition Drive, around the back of Waima.
Eventually all the other dams were connected to the aqueduct. The Lower Huia is pumped 100m vertically to join the Upper Huia water feeding into the top of the tunnel section. Water from the Lower Nihotupu dam is pumped 113m vertically to join at Mackies Rest. Part way along the Exhibition Drive track, the Upper Nihotupu water now also feeds in.
In 1999 Watercare won the Arthur Mead award for upgrading the Aqueduct. The award is presented by the Institute of Professional Engineers for projects that protect or enhance the environment.
Sadly, another 18 years on the now 90 year old aqueduct is now due for replacement.