Water will remain a key issue

 Water quantity and quality have been in the headlines throughout the holiday season. Heavy rainfall in some areas, drought in others and concerns about ‘pollution’ everywhere – valid or not.

Launching the Land Air Water Aotearoa (LAWA) website in December, Minister Nick Smith pointed out that it was beaches in urban areas that were attracting attention over safety for swimming. Early in the new year it was, again, the Piha lagoon that made the news because of high E. coli later tracked to leaking septic tanks.

Water quality is a New Zealand issue; national standards for water quality announced by the government last year are designed to improve the way fresh water is managed. 

In particular, the ‘The National Policy Statement for Freshwater Management 2011’ requires that councils set freshwater objectivesfor freshwater bodies that reflect national and local aspirations, and to set flow, allocation and water quality limits to ensure those objectives are achieved. It also requires councils to manage efficiently within those limits, avoid over-allocation and address existing over-allocation. Councils must manage land use and water in an integrated way and involve iwi and hapū in freshwater decision-making.

Reflecting national and local aspirations requires consultation and agreement but conflicts continue. 

The Ruataniwha dam decision hinged on keeping nitrate in rivers at or below 0.8 mg dissolved inorganic nitrogen per litre of water. This figure was identified last year by expert witness ecologists as being critical for river health. NIWA (National Institute of Water and Atmospheric Research) scientists, however, have indicated that ‘grading nitrate concentration for high conservation value systems (99% protection) is 1.0 mg N as nitrate per litre, and for 95% protection is 2.4. 

Of further note is that in the UK, the River Thames has a nitrate concentration of over 6 mg N/L, and is home to over 120 species of fish. These fish have returned to a river that was, due to sewage discharge, considered to be biologically dead at Tower Bridge in 1985.

The Thames is now regarded as healthy at least in part because of the fish population.

The debate on water quality is important in the decisions about water storage and irrigation. Concerns hinge on the fear that increasing irrigation opportunities will lead to intensification in agriculture, resulting in more nutrient loss to waterways. What doesn’t appear to have been considered is how irrigation water is applied on farm – yet research involving the Precision Agriculture Centre at Massey University, with researchers from Landcare, has shown that variable rate irrigation (VRI) has the potential to reduce nitrogen loss, reduce energy and water requirements, and increase production. 

VRI allows farmers to apply water only where necessary, avoiding leaching and surface runoff. Specifying type of irrigation involved in the proposed irrigation schemes could go a long way to alleviating community concerns about water quality.

The government’s overview of freshwater reform states that New Zealand receives 608 billion cubic metres of water annually, but uses only 1.8% (excluding hydro-generation).

 It is the 597 billion cubic metres of water that is currently running out to sea (via hydro-electricity generators in some cases) that is of concern. Farmers across the country would be happy to apply it to the land. VRI would allow them to do so efficiently, protecting waterways while increasing production from the soil. The International Year of the Soil can be used to raise awareness of the fundamental relationship between soil and water in agriculture, and allow some progress on managing both.

• Jacqueline Rowarth is professor of agribusiness at the University of Waikato.