Crunch time approaches for Ruataniwha water storage scheme

The dam divided the region. Photo / File

A decision on the future of the controversial Ruataniwha water storage scheme in the Hawke's Bay is looming, with Hawke's Bay Regional Council set to consider a review on its risks at a special meeting tomorrow.

The council is to consider the findings of its review into the scheme and is likely to seek further advice before a formal decision is made on its future at a council meeting on May 31, it said in a statement. The review examines the legal, financial, economic, engineering and environmental elements of the scheme, and the implications of withdrawing from it.

The $275 million water scheme proposes to create a 93 million cubic metre reservoir to store water in the upper Makaroro river to improve river flows for agricultural use in the Tukituki River catchment. It's estimated it would provide irrigation for 25,000 hectares of farm land in central Hawke's Bay. The scheme has divided opinion because it would allow farmers in the often parched central Hawke's Bay to ramp up production but also poses risks to the region's waterways that are already under pressure from agricultural and industrial runoff.

A full uptake of water under the scheme is forecast to increase the region's annual gross domestic product by between $130m and $380m, and create between 1,130 and 3,580 jobs.

The review describes the scheme as an "unprecedented intervention" for any regional council in New Zealand, seeking to generate better environmental outcomes with economic and social benefits via commercial water storage. The council first embarked on a project to address low summer water flows in its catchment in 2012, which developed into the Ruataniwha scheme, with $19.5m invested to date.

"The area of greatest uncertainty and risk for the council relates to the environmental management challenges for water quality arising from land use in the Tukituki catchment," the review says, noting that substantial environmental risks and uncertainty exist for the council in the catchment with or without the Ruataniwha scheme.

Land use on the Ruataniwha Plains is already dominated by intensive livestock production and the review concludes that the scheme will need to facilitate land use away from this to lower forms of nitrogen leaching, such as arable farming, vegetable cropping and horticulture, such as apple and grape production.

It says the Ruataniwha scheme provides a framework with stronger controls on farms, more flexibility and economic upside, as well as improving river flows in dry summer conditions; however, it is not possible to rule out scheme-enabled irrigation making the current nitrogen management challenge worse if it cannot transition land use effectively.