Wild weather continues to lash Northland with widespread flooding and slips. Video / Kevin Thorne / Rachel Ward / Scott Thomson
Despite a deluge of rain over the weekend, residents in Whangārei and Paihia are being asked to reduce water usage this week after storm-damaged treatment plants left reservoirs low.
Whangārei and Far North District Council warned residents to urgently conserve water on Saturday after Friday night's downpour left water treatment plants in Whangārei and Paihia out of action.
While most affected plants are now operating again, councils are asking people to conserve water this week after reservoir levels dropped dramatically.
Whangārei District Council water services manager Andrew Venmore said the Friday night storm - what meteorologists described as a 1-in-500 year downpour - impacted both the Poroti Water Treatment Plant and the Whau Valley Water Treatment Plant, therefore affecting Whangārei city's water supply.
The Poroti plant was completely flooded leaving all pumps underwater. Venmore said they need to be replaced or dried out and repaired which would take "several weeks".
"Effectively that treatment plant is no longer useful for the short term," he said.
The Hātea River after the 1-in-500 year downpour. Photo / Paul Shaw
Meanwhile, the storm washed debris into the Whau Valley Dam - turning it into the colour of the Hātea River - and as a result the Whau Valley Water Treatment plant struggled to cope with quality of the water.
It had to be shut down temporarily and was brought back to a normal flow about 6am yesterday.
With the plants out of action, water from the reservoirs was being used. This caused levels to drop dramatically - the main reservoir at Fairway Drive dropped to 13 per cent on Saturday night.
"We were within half an hour maybe of running out of water last night (Saturday)," he said.
"They're all really low at the moment and we're trying to get more water in them. That's why we're needing people to save water because if we can't save more water than we're producing, we will run out."
The Whau Valley Dam a few days before the storm. Photo / Tania Whyte
Venmore advised people to use as little water as they can. Do a full load in the dishwasher rather than half, or wash them by hand; only do laundry if you need to but if it can be put off until later in the week then do so, have shorter showers and only flush the toilet if you need to.
"Certainly don't go around water blasting the house or driveway - I know that might be tempting for a lot of people given there is a fair bit of mud and debris around the place. But if people can avoid using water to clean-up, for at least a couple of days."
The Paihia Water Treatment Plant - which was damaged in the deluge - is also now back in operation but Far North District Council infrastructure manager Andy Finch said the priority now was to recharge storage reservoirs to ensure backup supplies are available.
"I want to thank households and businesses for reducing water consumption yesterday. This helped get us through the immediate crisis.
"However, we still need all those connected to the Paihia supply from Waitangi to Opua to continue conserving water for the time being while reservoirs refill."
Finch said it will take at least two days for the reservoirs to re-charge, particularly the large Paihia reservoir.
Meanwhile, the Russell Wastewater Treatment Plant is no longer overflowing and the treatment plant is working at full capacity to meet demand.
The council has spoken to the Northland District Heath Board about the spill and it is advising people not to collect shellfish or swim in the wider Uruti Bay area for at least five days.
It said all harbours in the district should be treated with caution following very heavy rains as waterways will likely be impacted by pollutants from various sources, such as farm runoff or private septic tanks inundated by flood waters.
