With no significant rainfall since November, a man-made lake supplying water to South Canterbury farmers has forced an end to irrigation 10 weeks ahead of the usual season close on May 31.
The level of Lake Opuha, near Fairlie, dropped below 373m (4%), which brought the 2023-24 irrigation season to an end on March 19 for Opuha Water Ltd (OWL) shareholders and water users.
Environment Canterbury issued a Water Shortage Direction to OWL, which allows the minimum environmental flows to reduce to three cumecs, transitioning to natural flows where inflows into the lake equal outflows from the dam with the lake level 370m (0%).
The primary objective of this approach is to preserve the river connectivity for as long as feasible.
This is a situation that no one in the community wanted to see eventuate, South Canterbury irrigation co-operative OWL chief executive Bjorn Triplow said, but it is important to acknowledge that the Opuha Dam has done exactly what it was designed to do – provide environmental flows, community supply and reliable irrigation to the South Canterbury community.
The dam generates electricity for the national grid for about 4000 households and supplies water to 16,000 hectares of farmland.
“Unfortunately, the persistent El Niño weather pattern we are experiencing along the east coast has pushed the dam to the limits of what it can provide,” Triplow said.
The prolonged absence of meaningful rain resulted in a “strikingly low” lake level coming into autumn.
“Ordinarily, the lake undergoes several filling cycles through the year, but this pattern has been disrupted.”
It has been almost a decade since the lake dropped so low with lake storage plummeting to within 50mm of zero in the 2014-15 summer.
The Ministry for Primary Industries recently declared a medium-scale adverse event in the top of the south, which has now been extended to include all districts in the Canterbury and Otago regions, based on the extended period of very dry conditions affecting the livestock sector in particular.
Meanwhile Irrigation NZ is pressing ahead with water storage projects it proposes as a critical component of climate adaptation and land use change.
IrrigationNZ chief executive Vanessa Winning said NZ has demonstrated to the government the need for enabling policy to build resilience from droughts, floods and “those times in between”.
She said early engagement with the key ministers in the collation has set the stage for new policies endorsing water storage.
Geared towards national, regional and local on-farm adaptation, these policies focus on securing water availability for land use, particularly in areas with highly productive soils and those supporting horticultural production.
IrrigationNZ participated in the consultation for changes to the fast-track consenting regime.
Winning said it’s pleasing to see the government demonstrating support for projects that need help managing the resource management minefield, reducing reliance on river run and supporting the infrastructure needed to grow food and support the environment.
IrrigationNZ has presented four projects it is eager to begin, with details on the Bill review and project list now expected in early April.
“Focusing on water management, we’re seeing a shift towards strategic climate resilience and support for farmers transitioning land use. Fast-track consenting and funding for water storage projects mark a significant change.”
Key focuses include groundwater release, managing over-allocated catchments, community engagement, integrating with drinking water and renewable energy, and supporting iwi and hapu to thrive while improving the environment of our flora and fauna.
“We need to get the balance right. There is enough water for all if we capture and store it properly.
“If we do this well, we will keep our social licence and support our communities to manage through changing climatic conditions, provide choices for productive use and help our communities prosper.”
While new projects are exciting, Winning said it’s crucial to improve water efficiency and outputs to demonstrate leadership in water management.
This credibility is vital for discussions with regulators and communities, especially evident in schemes and irrigators in Canterbury and Otago.
Water infrastructure projects proposed by IrrigationNZ for the coming year in order of priority are Tuki Tuki in Hawke’s Bay; Falls Dam, North Otago; Wairarapa scheme revamp; and Klondyke water storage, Mid Canterbury.
“We expect these projects to employ a robust decision-making process.
“They are genuine whole-of-community projects and it will be crucial to have the community on board to join up solutions where everybody wins.
“People do understand if we are going to build resilience for our farming communities, particularly growing industry such as horticulture, then water storage is the genuine enabler,” Winning said.
“Like everyone else, we are now waiting on government to put the [fast track] list out.”
