Downpours in west Auckland see spike in dam levels

Photo: Lower Nihotupu Dam in the Waitākeres after the downpour.

The deluge of rain in west Auckland over the past 24 hours is rapidly filling up Auckland’s Waitākere dams and has boosted the city’s total dam storage by more than 7 per cent.
The highest catchments feeding into Waitākere, Upper Nihotupu and Upper Huia dams have all recorded more than 200mm of rain in just 12 hours.
Auckland Mayor Phil Goff says: “The heavy rain over the past 24 hours which has caused flooding in the north and west of the region has also had a significant impact on Auckland’s dam storage levels.
“Total dam storage was at 72.1% at 10am this morning, up from just 64.9% before the downpours began—an increase of more than 7 percentage points.
“Auckland Emergency Management and emergency services are working to support those affected by flooding and we ask everyone to stay safe and call 111 if they are in immediate danger.
“The flooding is also affecting Watercare’s ability to deal with wastewater overflows. These can be reported to Watercare as normal and will be addressed as soon as it is safe to do so.”
Our chief executive Jon Lamonte says: “We’ve had more than a month’s rain in 12 hours in our higher Waitākere catchments.”
The rain means Waitākere, Upper Huia and Upper Nihotupu dams are now spilling, and the lower dams are filling up quickly.
“Upper Huia Dam was just 45 per cent full at 9pm last night, and by 6am it was spilling,” Lamonte says. “Our western dams are much smaller than our Hūnua dams, and therefore they fill up much more quickly in heavy rain.”
The Hūnua catchments received between 30mm and 50mm overnight.

“While this rain is certainly helpful in terms of our water storage, we are still recovering from drought and we need to continue to be mindful of our water use. Aucklanders have done an outstanding job over the past year and we’ll need to keep up the great work with these water savings, especially when the days start getting longer and warmer.”

The deluge has caused varying water quality at Waitākere Dam, and as a result, the Waitākere Water Treatment Plant will be shutdown for at least the next 24 hours.
The rain also means Auckland’s wastewater network has been inundated with stormwater, which is causing wastewater overflows in west Auckland.
“Our crews can’t deal with these overflows until the flooding has subsided, but please do report any overflows on our website – we will clean these up as soon as it is safe to do so,” Lamonte says. “This may take longer than normal, particularly with more rain expected and our backlog growing.”