If you’re heading for a river or lake in the north or east of the North Island this summer, check the water before you go. Northland’s rivers are already well down, and forecasters favour below-normal rainfall across the region from November to January.
It’s been a dry spring up north. Northland had seen just 30–50 mm of rain in October by the 28th, regional council monitoring manager Jason Donaghy told Farmers Weekly, when the month would normally bring 90–100 mm. The same report has river flows across Northland ranging from below normal to extremely low. September had been dry too, and the council’s mid-October update found September flows lowest through the east, the mid-north and the south of the region.
Northland isn’t on its own. Earth Sciences New Zealand’s latest seasonal outlook, out on 29 October, favours below-normal river flows for November to January overall in Northland, Auckland, Waikato and the Bay of Plenty, and more strongly still in Gisborne, Hawke’s Bay and Wairarapa. Its Hotspot Watch the day before flagged dry ground across southern Northland, the far eastern Bay of Plenty and around East Cape.
The culprit is El Niño, which forecasters expect to rank among the strongest on record, with its peak likely between November and January. It pushes more westerly weather across the country, which tends to leave the north and east dry. Down south, river flows and lake storage remain generally healthy, and wetter conditions are favoured in the west and far south. Meridian Energy’s September operating report put South Island hydro storage at 133 per cent of average on 12 October, while the North Island sat at 78 per cent.
What it means if you’re heading inland
Lower water changes the boating in obvious and less obvious ways.
Ramps are the first thing many people notice. Marine insurer Mariner Insurance’s October El Niño guide warns that some North Island lake and river ramps could be shallower than owners are used to, so it’s worth a look before backing the trailer down.
On the water, less depth brings the bottom closer. Gravel bars, sand banks, logs and rocks that normally sit well below the hull can end up just under the surface, and channels you know by heart may not be where they were. Outboard skegs, props and jet units are the parts that tend to find them first. Taking it slower in unfamiliar or shallow stretches, and keeping a sharper lookout, is worth doing wherever the water is low.
Rivers that are only runnable with a decent flow behind them may simply not have enough water, and the small creeks and side branches are usually the first to go. The live river flow and level gauges regional councils publish online are the quickest way to check before making the drive.
Water quality is the other thing to watch. Low flows and warm water can lead to more algae and cyanobacteria, Hawke’s Bay Regional Council members heard at a recent briefing, 1News reported.
A new gate at Taharoa
Northland lake boaties have one more thing to plan for this summer. As Boating NZ reported, a PIN-controlled gate went up at the Lake Taharoa ramp at the Kai Iwi Lakes ahead of Labour Weekend to keep out the invasive freshwater clam. Taharoa is the only Kai Iwi lake where power boats are still allowed, and you now need to complete Northland Regional Council’s online Check, Clean, Dry self-certification, ideally about 48 hours before you travel, to get the PIN. Hang on to it, as you’ll need it to get back out.
Elsewhere, Otago Regional Council’s Labour Weekend reminder asks boaties to dry their gear for at least 48 hours before moving to another waterway.
Earth Sciences says a rain event in the north in early November is possible, but expects dry spells will win out over the season as a whole.
