New Zealand's growing thirst for water

Lower Nihotupu Dam in Auckland's Waitakere Ranges. Photo / Brett Phibbs

Demand is up but minister insists supply is far from being in danger, reports Jamie Morton.

Newly published data has shown New Zealand has become thirstier for water, with the country's weekly allocation for water increasing by a third in the space of 10 years.

But despite dramatic increases in water use, Environment Minister Nick Smith says there's still more than enough to go around - and room to use more.

A sharp rise in the amount of water being allocated for uses such as irrigation has been highlighted in a new section of Land, Air, Water Aotearoa (LAWA), an online environmental monitoring website run by the Government, regional councils and the Cawthron Institute.

It showed how by 2010, the most recent year for which data had been collected, activities such as irrigation had been allocated nearly twice as much water as they had been a decade before.

The Canterbury, Southland and Otago regions accounted for the lion's share of the total amount of water allocated each week - around 86 per cent - and while in Southland's case the reason was hydro generation, the main water use in Canterbury and Otago was irrigation.

Between 1999 and 2010, the largest increase in allocation was in Canterbury with a growth of 98.2 million cubic metres a week - a 65 per cent change.

Other regions such as Auckland, West Coast and Nelson had the majority of their allocated water for public drinking water supply and manufacturing processes.

On average, the percentage of water used of the maximum allocated was around 65 per cent, although most regions used less than half of their allocation.

The 2010 figures showed how Auckland had used around 69 per cent of its allocation, which was mostly consented for drinking water.

In all that year, the country had been allocated 27 billion cubic metres of water to use or drink - enough to fill half of Lake Taupo.

Fran Wilde, chairwoman of Local Government New Zealand's regional sector, said water had a "vital input" for the industrial, primary and tourism sectors which the country relied upon, and some regions were approaching water resource limits where water demand outstripped supply.

"This can constrain economic opportunities and put pressure on our river ecosystems."

The Green Party's freshwater spokeswoman, Catherine Delahunty, was concerned at the increase in the water take for irrigation.

"The LAWA research shows the water allocations are out of balance, unfair and will not protect water quality."

But Andrew Curtis, chief executive of the lobby group Irrigation New Zealand, said the big increases had already happened and in most regions, takes from the ground or rivers for irrigation had now been fully allocated. He expected new consents to have tapered off since 2010.

"The issue in New Zealand has never been water - there is plenty of water there, particularly if you store it - the challenge is more how the water is used and that comes down to the water quality side of things, and how we minimise footprints of intensive agriculture."

Dr Smith said the Government had an active reform agenda around setting limits on both nutrients and water allocations.

"We don't have a water shortage in New Zealand, but we have some areas at times of the year when we have water constraints."

Compared internationally, New Zealand had an abundance of fresh water and was ranked fourth out of 30 OECD countries for the size of its renewable freshwater resource on a per capita basis.

Dr Smith said the amount of freshwater available in the country equated to around 145 million litres per person each year - and we used about 1.8 per cent of the resource.

"So while the growth looks dramatic, we have plentiful resources and potential for further economic development from that freshwater."

The LAWA website would be updated later this year with more data on freshwater, as well as air quality monitoring.