Forum - Let's crunch the facts and the debate on irrigation

The Labour Government’s decision to cut additional funding for new irrigation plans has sparked debate over the value of irrigation to agriculture and the economy in recent weeks. According to the 2017 Manifesto on water policy, Labour will “Honour existing commitments, but remove Crown subsidies for the funding of further water storage and irrigation schemes”, a measure falling under the government’s wider aims to improve water quality nationwide, and “restore our rivers and lakes to a truly swimmable state within a generation”.

For Dr. Mike Joy, senior lecturer in Ecology and Zoology at Massey University’s Institute of Agriculture and Environment, the negative environmental impacts of intensive irrigated systems are undeniable.

In an August article entitled “Damn the dams” Joy lambasted current farming practices, affirming his interpretation of the national “quest” to drive up agricultural production, intensive land use and water storage schemes are being pushed ahead, while adverse environmental impacts are downplayed or outwardly denied. 

The article points to assertions irrigation reduces ground and surface water levels, thereby suggesting it diminishes natural water flow, and as a consequence raises temperatures, alters sediment movement and increases nutrient concentrations. Such effects, Joy believes, render rivers “unsuitable as breeding grounds or as habitat for aquatic life, as well as destroying them for human recreational use”.

Additionally, the article cites secondary impacts on water quality, affirming irrigated farms “discharge more nutrients and other pollutants than non-irrigated farms due to the higher stock numbers that irrigation allows”.

These sentiments were shared in June in a report by Greenpeace. The report claimed irrigation “drives water pollution by allowing more intense livestock farming, helps leaching of contaminants and reduces water flows so contaminants are not diluted”.

Sound science?

It is important to keep in mind the statements of Joy, and other like-minded environmentalists, may be informed as much by the purposes of activism as the need to provide a balanced scientific argument.

In April, Doug Edmeades published a piece for NZ Farmer which touched on this point, suggesting Joy could be termed an “'Issue Advocate' pushing a point of view, rather than “a scientist who proceeds logically, cognizant of all the data”.

This seems particularly apparent when looking at the central idea around which much of the anti-irrigation rhetoric is pinned: that intensified irrigation automatically equals more dairy intensification.

According to statistics from Dairy NZ, fewer than 2,000 of the nation’s herds use irrigation; only around 16%. In fact, Andrew Curtis of Irrigation New Zealand says over half of New Zealand’s irrigated land is not used for Dairy Farming, but for a range of other exploits like cropping, sheep farming, and fruit, vegetable and wine growing.

Furthermore, environmentally slanted arguments tend to ignore the huge benefits of irrigation to the economy - the statistics and examples suggesting irrigation's environmental effects may actually be fairly limited - or the fact irrigation schemes can be environmentally beneficial.

In a recent edition of “The Country”, Jamie McKay pointed out that, at the 2017 annual river awards, the Pahau River in North Canterbury, situated in one of the most intensely irrigated catchments in New Zealand, was awarded the supreme prize for most improved river, achieving E coli reductions of 15.6 percent per year for the last decade.

This fact was mentioned during an “Irrigation Edition” of the show in which McKay hosted head of the Environmental Protection Agency Jacqueline Rowarth.

Rowarth ruffled feathers in an interview with the Otago Daily Times, where she spoke of the “great boon” irrigation can provide to the environment when carefully managed, and suggested that in its support of the agricultural economy, irrigation facilitated environmentally friendly projects like controlling rabbit populations and preventing the spread of wilding conifers. As expected, Joy and prominent Greenpeace leaders were quick to dismiss these notions, suggesting Dr. Rowarth was “out on her own” in her views.

However, she clearly isn't alone. Asked to offer his thoughts on the current debate, head of Irrigation New Zealand Andrew Curtis was similarly supportive of irrigation schemes as both a valuable asset to the national economy and a potential benefit to the environment.

Curtis pointed out that, as we move into the dryer, hotter summer months, irrigation becomes integral in providing a consistent food supply for towns and cities, and helping to reduce food shortages or price spikes due to drought.

He also pointed out irrigation’s huge economic benefit to rural communities, highlighting several studies from both Irrigation New Zealand and the New Zealand Institute of Economic Research that show for every 1,000 ha of irrigation at least fifty new jobs are created, meaning higher employment rates, more income, and a range of benefits from boosted school rolls to protection from the devastating effects of drought.

Whilst ready to acknowledge that “activities on irrigated land can contribute to water quality issues”, he also affirmed a range of actions were underway to address these environmental concerns, from environmental impact reduction plans in Canterbury, to farmers being asked to meet new nutrient discharge limits, and requirements to fence off waterways in intensively stocked areas.

Curtis provides factual support for Dr. Rowarth's assertions on the environmental benefits of irrigation. He cited the Opuha Dam in South Canterbury which is used to keep the Opuha river flowing during drought years and is released to mimic ‘natural freshes’ which flush-out algal growth. A similar effect is expected for a dam being constructed in Waimea.

He additionally pointed to research undertaken by the Foundation for Arable Research in New Zealand which has found “arable farms with irrigation leached less nitrogen than the equivalent dryland farms”.

Murray Doak of the Ministry for Primary Industries acknowledged new irrigation scheme development can increase the risk of nutrient loss to waterways in the locality. However, he also pointed out that nutrient limits are set for schemes as part of their water use consent, and audited farm environment plans are enforced by regional councils to ensure these limits are not exceeded.

Regional council involvement in water use is something often overlooked amongst the general population, particularly from those in urban settings, who tend to assume that farmers can take and use water as they please.

On the contrary, according to information provided by IrrigationNZ, the situation is quite detailed.

Farmers must apply for, and be granted, a water permit by their Regional Council.

The permit is a legally enforceable undertaking involving a ‘take and use’ process describing the site-specific conditions that need to be followed.

All takes from New Zealand rivers have a ‘minimum flow‘ applied to them. This means when a river’s flow drops below a certain level the water take must stop. The permit also states:

  • how much water can be removed at any one time,
  • total water take over the irrigation season, and
  • exactly what this water is to be used for.

A fee is charged for the first application, and a reduced fee is charged for any concurrent applications. Additionally, the applicant is charged hourly rates for the use of water scientists, technicians, and any other persons involved in the take and use of water, and is charged annually for compliance monitoring.

Some may be surprised to discover how intensive a process accessing and using water is for farm-owners, but most importantly, it shows the measures and regulations are in place to ensure that water is being used efficiently throughout the nation and with strict management.

Perhaps for Greenpeace and their supporters, such information needs to be taken on board.

The audited Farm Environment Plans highlighted by Doak have already been implemented in over 3000 farms according to Andrew Curtis.

Furthermore, precision technology is in use in 70 percent of Ashburton farms according to a 2016 study run by IrrigationNZ and ECan, part of the irrigation efficiency programme that looks to reduce costs, improve resource use and minimise impacts on the environment.  These are the areas in which environmentalist efforts should be focused: projects that ensure the continuation of irrigation schemes, but with emphasis placed on their water-use efficiency, and overall benefit to the environment.

Interviewed on The Country this Wednesday, Jacinda Ardern reaffirmed her intentions with regards to irrigation: "There are some commitments that have already been made, and it wouldn't be right for us to withdraw from projects like Waimea given the stage they are at, but going forward we certainly will not continue to subsidise those large-scale schemes".

However, Andrew Curtis (speaking to the Otago Daily Times on Sunday) believes Central Otago is set to see an increase in the “speed and intensity of droughts” in the coming years as a result of the local climate becoming warmer and drier. If this is the case, it would appear that the future intensification of irrigation schemes is not only an inevitability, but a necessity.

Perhaps for Greenpeace and fellow staunch environmentalists focus should be placed, not on preventing these future schemes, but on ensuring they are as eco-friendly and efficient as possible, allowing New Zealand to maintain its "clean, green" reputation whilst keeping the lifeblood of our economy up and running.