Large pond takes shape

The biggest investment since the Lower Waitaki irrigation scheme was built in the 1970s is taking shape at Ferry Rd.

The Lower Waitaki Irrigation Company has started building a large buffer pond, which will cost about $800,000 (excluding land).

It marks a major change to the scheme, which irrigates about 19,500ha, by meeting the demands of changing irrigation and improving reliability of supply to shareholders on its extremities.

The pond will hold 120,000 cubic metres of water at capacity, and is being constructed primarily to allow the scheme to better cope with conversions from border-dyke to spray irrigation, which is becoming more common across the scheme.

Race manager Ross Bishop said the pond would provide increased security of supply to the scheme's users, by taking out the marked "highs and lows" that occurred now in race levels.

Company chairman Chris Dennison said the pond would bring a range of benefits beyond the immediate supply and demand requirements of the scheme's shareholders, particularly in relation to water-use efficiency through reduced by-wash.

"We are demanding our shareholders become more efficient with their water use, so the scheme must also become more efficient," he said.

The pond would also provide a more reliable supply of water to Oamaru town's water supply and industrial users, including Alliance Group's Pukeuri meat plant, and better quality in floods.

New automation could be put into auxiliary races (which come off the main supply race), for better water capture and re-distribution, as well as ensuring farmers at the extremities of the scheme had increased reliability.

At its deepest point, the pond would be 2.7m deep.

Native shrubs planted on the banks would create a habitat for birds and provide amenity value.

Mr Dennison said the work the company was undertaking "ticks all the boxes across the areas of community wellbeing".

The company's board of directors had put a great deal of time into ensuring the design and operation of the pond would be of the highest standard, with multiple safety mechanisms put in place.

The site was ideal for the pond due to the clay soil, which makes a natural lining.

Work on the pond is due to be completed by August of this year, to coincide with the start of the next irrigation season in the spring.

It is being constructed under a land use resource consent issued by the Waitaki District Council in March.

- david.bruce@odt.co.nz