Northland's small coastal catchments are set to become the next "victims" of the region's "unrelenting drought," according to the Northland Regional Council, which on Tuesday was preparing to issue water shortage directions in 23 communities, restricting the use of bore water to 'reasonable' household and stock welfare needs.

Water and waste manager Ali McHugh said more than two dozen aquifers were nearing, or quickly heading toward, their lowest levels on record.

"For those drawing water from bores in these areas, this means if that they have not already, they may soon begin experiencing issues such as water becoming noticeably salty and other bore behaviour they have not encountered before," she said.

She expected small, shallow coastal groundwater systems to fall to significantly lower levels than would normally be seen over the next two to three months, raising the real risk of saltwater intrusion.

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"There is a real risk that there will be water that's unsuitable for drinking, or even no water at all, as shallow bores become unable to pump water and deeper bores are impacted by saltwater moving inland," she said.

"If too much saltwater intrusion occurs it could take many months for things to improve to a point where a bore water supply could be used again.

"In these conditions, it's best to pump slowly from a groundwater system into a tank, which allows more recovery time for the aquifer and acts as a buffer if any issues arise with the bore."

Ms McHugh urged people to save all the water they could, if they were not already doing so, and, if possible, reduce pumping rates further.

In small coastal settlements that were heavily reliant on aquifers, she added, most bore water was taken by individuals as a permitted activity, meaning no resource consent was required to take reasonably small amounts to meet daily domestic and stock drinking water needs. However, in drought conditions, most groundwater users were just as much at the mercy of the lack of rain as those who relied on streams and lakes.

Water shortage directions, if issued, would prohibit taking water for irrigation, watering gardens (other than with recycled domestic water from laundries, kitchens and bathrooms) washing cars or boats, water blasting and filling swimming and spa pools.

"We will be monitoring water use, and those found using non-essential water may find themselves facing enforcement action," she said.

Anyone who had a critical need to take water, and was unclear about whether they would be able to do so under a water shortage direction, should contact the regional council on (0800) 002-004.

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WHO'S IN TROUBLE?

The coastal aquifers identified by the Northland Regional Council as susceptible to saltwater intrusion include those at Russell/Tapeka, Taipā to Mangonui, Taupō Bay, Tauranga Bay, Matauri Bay and Te Ngaere Bay. Only one, Kaikohe, of nine more that were expected to be affected "soon," was in the Far North.