Auckland’s ‘very dry’ long-range forecast reinforces need to save water

Upper Mangatawhiri Dam 8 August 2020
Upper Mangatawhiri Dam, 8 August 2020
Credit: Chris Hannent

A long-range weather forecast reaffirming earlier predictions of an extremely dry Spring means it’s now more important than ever for Aucklanders to save water.
Auckland received 40 per cent less rainfall than normal in Auckland between November 2019 and May 2020, making it the region’s worst drought on record.
Despite recent rainfall, Auckland’s total dam storage level is currently 60 per cent, when normally at this time of year it would be above 80 per cent.
MetService meteorologist Georgina Griffiths says August looks likely to deliver some decent rainfall to Auckland, but that’s where the good news ends.
“Our long-range models have always been keen on a drier spring for Auckland. The latest forecasts continue to signal an extended run of well-below-normal rainfall between September and December. The main culprit is expected to be frequent high pressure on our weather maps, meaning a lower turnout for the rain makers.
“There is the possibility of tropical storms providing a good dose of rain early next year, but it really is too early to tell, and even if they do arrive, we would need the rain to fall in the right places.”
Last month, thunderstorms that flooded the Coromandel and Northland almost missed the Hūnua Ranges entirely.
“We can expect some intermittent easterlies, which may bring good amounts of rain, but the Hūnua Ranges are often sheltered from these systems.”
Watercare head of servicing and consents Mark Bourne, who is coordinating the drought response, says the latest seasonal forecast means outdoor water restrictions will likely continue into summer.
“Aucklanders have been making really impressive water savings since restrictions began, and if we can all continue to keep our water usage down, even if we do have a very dry spring, we should start summer with our dams above half full.
“We are also making steady progress on a number of projects that will give us an additional 40 million litres a day by Christmas, compared to what we had available last summer. With these new sources, careful management of our existing sources and continued savings by Aucklanders, we expect to avoid the need for more severe restrictions.”
This month the completion of the Pukekohe East reservoir will allow the Waikato Water Treatment Plant to treat and deliver 175 million litres of water a day (MLD). Currently it is treating up to 165MLD, which is up 15MLD from last summer.
“In September we will be returning the Hickey Springs Bore in Pukekohe to service. Construction is underway on a modular treatment plant that will provide up to 5 million litres a day.
“Meanwhile we have demolished the old Papakura Water Treatment Plant to make way for a new plant that will treat water from Hays Creek Dam. We will be treating up to 6 million litres a day from this dam by Christmas, and next year will be able to increase this to 18 million litres a day.”
An upgrade to the Onehunga Water Treatment Plant, which treats water from an underground aquifer, will also increase production by another 4MLD in December.
Bourne says daily water consumption figures show Aucklanders have been consistently heeding the call to save 20 litres per person every day.
“Our target for August is 405 million litres of water a day, and our rolling weekly average is well below that at 392 million litres a day. That’s a tremendous effort – under normal circumstances we had anticipated daily demand of about 430 million litres at this time of year – so to be under 400 is something to be really proud of.
“We’re also very pleased to see so many businesses in the outdoor cleaning, car washing and construction industries are supporting our water saving efforts by using non-potable water in their daily operations.”
With outdoor water restrictions likely to remain in place over summer, anyone wanting to install a rain tank is encouraged to do so as soon as possible.
“Auckland Council recently waived resource consent fees and streamlined the process around installing rain tanks, so if this is an option you’re considering, now is the time to do it,” Bourne says.
Aucklanders who rely solely on rain tanks for their drinking water are advised to check tank levels regularly and order water early as private water carriers are expecting high demand.
Click here for water saving tips.