Below Benmore Dam, Waitaki, willow trees grow. A digital painting by Derek Golding.
The dam is the largest earth-filled water-retaining structure in New Zealand. Its core is low permeability clay material, supported by two massive shoulders of river gravel. Lake Benmore has a volume of 1.25 billion cubic metres, about 1.5 times as much water as Wellington Harbour. The dam’s spillway can cope with 3,400 cubic metres of water per second, about 10 times the mean river flow.