Critical shortage of good data on use of precious water resource

This started as an investigation into who uses our water, how much, and for what.

A year, 15 Local Government Official Information and Meetings Act requests and one Ombudsman's investigation later, I still don't have reliable answers.

Given all water takes greater than 5l/s had to be metered by 2016, you'd think it would be easy to get good data on how much water is being used, and by whom. You'd be wrong.

An official  request to every regional council met wildly different responses. Auckland Council refused to provide any data, until the Ombudsman intervened. Waikato Regional Council initially failed to provide actual annual use figures for 80 per cent of its consents, including six of the 20 biggest consent holders. Greater Wellington also had huge data holes, including urban water supply figures, and reported use in one case was 350 times what the consent allowed.

Northland said it would take 125 hours and $9262 to manually extract the numbers. Ecan (Environment Canterbury) couldn't break it down by consent, because that involves manual work.

Some councils don't record annual volumes for consents that are monitored based on daily or weekly rates.

It turns out I'm not the first person to ask this question. Ministry for the Environment boss Vicky Robertson said in the ministry's Our Fresh Water 2017 report "A key takeaway from this report is the need to get better at collecting and reporting consistent data on fresh water ... More than half the water allocated (or consented) by councils is for irrigation, but we do not know how much of this is actually used."

Forest and Bird conservation advocate Kevin Hackwell says the lack of reliable information about how much water we're using, and for what, is "a huge issue".

"Here regional councils are, required by law to manage our water resource, it is a really contentious resource that they manage, and they don't have the basic bloody data."

As former prime minister Sir Geoffrey Palmer famously pronounced, New Zealand is a pluvial nation. With annual rainfall sufficient to fill Lake Taupo nine times, our rainfall figures per person are high by international standards.

But - as NIWA hydrologist Daniel Collins points out - averages are meaningless when there's so much regional variation.

"Rainfall is anything but even. A quarter of the water falls on the West Coast alone - well over 10 metres per year in some places – while parts of Otago and Canterbury receive less than 30 centimetres a year."

Climate change will exacerbate that, with less rain expected in the north and east - especially in summer - and more in the west and south. As the ground warms, more rain will also evaporate, reducing the amount that sustains our rivers and aquifers. And at the same time, dry farms and hot, thirsty mouths will need more water, Collins says.

"In most cases water demand is projected to increase, but the opportunity to abstract water in these areas is generally expected to decline."

So it would be helpful to know how much we're using now, to better understand what the future holds.

"We need to improve our water security and shift towards a more drought-resilient society. This doesn't necessarily mean securing more water. We also have to think about getting by with less – a society and economy with a smaller water footprint – and about building the resilience of people and nature to inevitable water shocks."

GNS head of hydrogeology Stewart Cameron also thinks we need to know more about our water resources - specifically what lies beneath. There are 200 mapped aquifers in New Zealand, which feed the country's rivers and springs and supply about a third of Kiwis' daily supply. But we don't know enough about what's in them, or how they work, Cameron says.

"The aquifer systems in New Zealand are relatively poorly understood, because New Zealand hasn't invested enough in fundamental knowledge acquisition for a long, long time."

Soaring extraction is depleting groundwater in some areas, including Southland, Otago, Marlborough, Tasman, Bay of Plenty, Gisborne, Northland and almost all of the Canterbury Plains. In extreme cases, such as the once-swimmable Selwyn River, falling aquifer levels can suck the life and flow out of the rivers.

"There's kind of hotspots where agriculture is able to be intensive if they can access water and I guess you'd say water was allocated without adequate knowledge," Cameron says. "And now they have to play catch up, because they'd made some bad decisions."

While irrigation efficiency is improving, there could be a lag time of decades or hundreds of years before the effects reach the land's deep reservoirs, Cameron says.

"Some areas - if the right practices are put in place - will improve reasonably quickly. Others haven't seen the worst yet and will continue to decline. I don't think New Zealand is doing enough at the moment, as a nation, to clean up our waterways. We're still on a very slippery slope down. Because our economy is agriculture based."

THE DETAILS

NORTHLAND

Northland Regional Council failed to provide any actual use data for its water consents. It said to do so would take its staff at least 125 hours and cost $9262.50

Based on consented volumes, its biggest metered users are public water supplies (62 per cent), pasture irrigators (19 per cent), horticulture (11 per cent - mostly avocado orchards) and quarrying (2 per cent).

AUCKLAND

After initially refusing to provide any of the data requested, Auckland Council did produce actual use figures, after the Ombudsman intervened.

The lion's share of Auckland's water goes to its residents (86 per cent), followed by industrial users (3.2 per cent). More than three quarters comes from dam water.

WAIKATO

Waikato Regional Council initially failed to provide actual use figures for 80 per cent of its consents, including six of the 20 biggest users. Because consents were often granted by daily or monthly rates, it did not always record the annual volume used.

Additional figures filled some gaps, but still provided no 2016 values for big users Solid Energy, Taharoa Ironsands and Carter Holt Harvey. Other values were wildly out, with one farm reporting use of 25 million cubic metres, against a consented maximum of 65,000. 

Based on consented annual limits, town supplies are the biggest water users, followed by agriculture, timber processing and quarrying and mining.   

BAY OF PLENTY

Bay of Plenty Regional Council could not provide actual use data: "Although upon receipt of water-use records, the Regulatory Compliance team immediately checks for compliance with consented volumes, any further analysis is done through a water-data management database which requires some manual uploading of the records."

Six months on from the end of the water year those records still had not been manually uploaded. "Collation of this information would be extremely labour intensive so may incur a cost".

Commercial and industrial uses and public water supplies both make up about 30 per cent of consented volumes, followed by pasture irrigation. The majority of consents (70 per cent) draw from surface water rather than groundwater.

GISBORNE

Gisborne Council could not provide actual use figures in a usable format.

HAWKE'S BAY

Hawke's Bay provided some of the most comprehensive data, although some consents still had no metered use details.

Based on 2016/17 actual use, cropping, public water supplies, orchards and pasture irrigation are the region's biggest water users. Three quarters of its water comes from aquifers not surface water. 

TARANAKI

According to the data provided, town supplies and energy are Taranaki's biggest water users. However, several irrigators holding large consents had no annual use data recorded, and reported irrigation volumes were 18 times less than the total consented amount.

The vast majority of water use is from surface water.

HORIZONS

The Horizons region, which stretches from Ruapehu to Horowhenua and west to Whanganui, only supplied recorded annual volumes for half its metered consents. Based on the data provided, pasture irrigators are the biggest water users, followed by town supplies and meat processing.

About half its water comes from aquifers.

GREATER WELLINGTON

Greater Wellington's data has many holes and wild results cast doubt on its reliability. A golf club with a consent to use 199,000 cubic metres a year reportedly used 350 times that - 69 million m³, or more than the entire town supply of Auckland.

By consented volumes, drinking water is the biggest user at almost 60 per cent, followed by irrigation (28 per cent) and stock animals(11 per cent). 

TASMAN

Irrigation makes up about 65 per cent of Tasman's metered water use, followed by town supplies. The water source (surface or groundwater) was not provided.

MARLBOROUGH

Large numbers of Marlborough consents have no actual use recorded, despite requiring meters. In explanation, the council said "not all meters are required to have telemetery as yet or the permit may not be being utilised".

Based on the recorded use data provided, pasture irrigation, crops and grapes are the thirstiest users.

CANTERBURY

Ecan provided water use figures by activity, but could not break the numbers down to individual consents, as the process of comparing actual use to consents is complex: "It goes without saying that this doesn't stop us from assessing compliance with consents but it does mean that when our [staff] assess compliance with consent conditions they spend quite some time in pulling information together from a range of sources."

WEST COAST 

West Coast Regional Council failed to provide any actual water use figures: "Our current water meter data receipt and data management systems do not make this data easily trackable. This is something we are currently working on to ensure that we can fulfil monitoring requirements."

Based on consented volumes, water bottling is the biggest user, followed by irrigation and drinking water.

OTAGO

Otago did not provide use types, so no overall pattern of use could be established. The data also appears to include multiple duplicates.

SOUTHLAND

Pasture irrigation makes up the majority of metered water use in Southland. About 85 per cent of the water comes from the ground rather than rivers.

Source: https://www.stuff.co.nz/environment/108707532/how-do-we-use-water-we-still-dont-really-know