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Published: 2005-02-11 00:00:00

The demand for water for dairy pasture irrigation in the Waikato over the next 50 years is likely to be second only to that from hydroelectric generation, this week’s Environment Waikato Environment Committee meeting heard.

Dr Ed Brown told the Committee that farms most likely to convert to pasture irrigation were those where rainfall and soil characteristics limited grass growth making irrigation economically viable.

“Dairy research shows that increased pasture utilisation through increased stocking rates and improved pasture management is the greatest profit opportunity available to New Zealand pastoral farmers today,” he said.

Environment Waikato had developed a model to calculate which land was physically suitable for pasture irrigation and identified an area of up to 600,000 hectares if there was no limit on water availability. Ninety five percent of this land could be irrigated profitably at an average dairy payout of $4.20 – which meant there was potential for a large increase in the amount of irrigated land in the future.

However, in much of this area irrigation would be limited by water availability and in many areas by quality. The model also assumed that all farmers had access to sufficient capital to purchase irrigation equipment.

“If there is only moderate irrigation growth over the next 20 years, demand would be able to be met in most catchments by the currently available surface water and groundwater.”

However, the model did not cover an increase in water demand from other uses such as industry, stock water, frost protection and municipal supply.

Accelerated irrigation growth could mean that modelled water demand could easily far exceed water availability throughout the Region.

As more water bodies became fully allocated an increasing number of water takes would be assessed under discretionary rules. Under the current ‘first in, first served’ allocation system water resources could be fully allocated and not account for other future needs such as community supplies.

Cr Steve Osborne questioned whether the Council was moving fast enough on water allocation issues as water restrictions had occurred on the Waihou River in recent times and now towns were wanting to pump water out to rural areas.

Cr Jim Howland said consent processes were looking at better uses of water and, for the first time, had included re-using treated water in a consent process.

Water Allocation Project Manager David Speirs said metering was now required on all water takes to encourage efficient water use and to allow for trading and transferring of permits. Another major issue was how to secure supply for domestic water use.

“We can protect existing requirements but it is hard to project forward 50 years and be fair to everyone.”
Environment Committee Chairman Paula Southgate said the council needed much greater monitoring information to make sure water allocation was effective. Fair allocation of water was a major challenge for everyone.
For more information contact:
Dr Edmund Brown or David Speirs
Ph (07) 856 7184
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