Story: Irrigation and drainage
Page 4 – Irrigation after 2000
By 2006 about 776,000 hectares were under irrigation, three times as much as in 1985. This accounted for 77% of all water allocated for managed use. In Canterbury, which had 400,000 hectares of irrigated land in 2006, irrigation used 7–14% of the region’s total water resource.
In 2002/3 irrigated land contributed a net $920 million to New Zealand’s economy, 11% of the total farming contribution to the gross domestic product. It has been projected that further irrigation developments by 2013 of up to 470,000 hectares could earn an additional $660 million per year.
Water resource investment
For irrigation to expand, it was recognised that dam storage needed to be increased, and river flows need to be sustained. However, it has proven difficult to identify water resources suitable for storage, the process of applying for consents to take water can be expensive, and the financial investments required are large, despite attractive economic returns.
Large-scale community projects also involve inter-generational issues, with large costs lumped onto the present generation, but benefits continuing for an unlimited period into the future.
Irrigation problems in Canterbury and Otago
In 2007 Canterbury had the largest irrigated area in New Zealand, and the largest annual volume of water consented for use. However, consent reviews were likely to reduce entitlements, and so new applications were unlikely to be successful.
In Otago in 2007 water resources were heavily over-allocated where traditional mining rights were still in place. When these expire in 2021, water allocation will probably be reduced to protect the environment.
The problems evident in Canterbury and Otago in the early 2000s are expected to occur also in the other irrigated regions of New Zealand.
Likely water management changes
Unless there are changes to current and planned water management, new irrigation operators are likely to find it increasingly difficult to gain access to water that is reliable enough to justify the investment.
Many farms are changing from the old border dyke system to centre pivot spray irrigation, which uses about half as much water to the same effect. The cost of this is about $7,000 per hectare.
In future, existing and new irrigation operators are likely to be subject to more onerous consent conditions, requiring improvements in water quality and more efficient use of water. More measurement, monitoring and reporting will probably be required, higher charges imposed by regional councils, and tougher penalties for non-compliance.
Water trading rights will probably be available in the future, and water meters required to measure water used. South Wairarapa plans for water meters to be in place for all users after 2009.