The 2025-26 irrigation season has shown us once again that there’s no such thing as an average when it comes to describing the climate factors that drive irrigation demand and supply. While some aspects of it can be described as near-average, there have been some interesting extremes thrown into the mix.
We started off the irrigation season with high groundwater levels – among the highest recorded in the past 20 years in some parts of the Canterbury Plains – which relieved pressure on the supply side for irrigators that are subject to adaptive management conditions based on spring trigger levels.
In their end-of-summer climate summary, Earth Sciences New Zealand reported that summer temperatures were near or slightly below average for most of Canterbury, and rainfall was well above normal for most parts of the region. However, illustrating that averages never tell the full story, Winchmore recorded its lowest mean summer temperature since records began there in 1949.
Despite recording above-average rainfall for the summer, Christchurch was the driest of the six main centres. A lot of the variance from the average rainfall was driven by the storm that came through in mid-February. Banks Peninsula bore the brunt of this, with Akaroa receiving 243 mm of rain on February 16th, its highest daily rainfall total since records began there in 1977. As a result, Akaroa’s summer rainfall was also a record at more than three times the average. While rainfall totals from this storm were much less dramatic on the Plains, some lower Plains rainfall stations recorded around 80 mm of rain over two days.
Canterbury went into summer with lower-than-average soil moisture levels and ended the meteorological summer (December – February) with soil moisture sitting above average (largely due to the mid-February rain). Of course, the three months of meteorological summer are far from the full story when it comes to the irrigation season in Canterbury. As we’ve discussed in these columns previously, a long tail-end of the irrigation season, stretching into April or even May, can catch people out. This can be either through water resource pressure resulting in irrigation restrictions, or through seasonal allocations being exhausted.
To get an indication of how the irrigation season stacked up overall, we’ve modelled irrigation demand using climate data from Lincoln, with daily rainfall and evapotranspiration measured from 1960 through to the end of April 2026. This modelling shows that the total demand for the 2025-26 irrigation season was slightly below the long-term seasonal average. The first half of the season, particularly September – November, was tracking well above average. Things took a turn in January: although January accounts for 20% of the season’s total water use on average, the modelled value for this year was only 7%. Despite the large rain event, February was an above-average month, as were March and April. Our modelling for this year runs through to the end of April, but anecdotally irrigation has continued into May in some areas.
Despite ending up near the average overall, the 2025-26 irrigation season has illustrated the variability that we can get between months. This kind of variability reinforces that irrigation decisions need to be responsive to current conditions, rather than based on seasonal norms or expectations. A month such as January this year with abnormally low irrigation demand has the potential to catch you off guard. What might feel like the irrigation season winding down early can just be a lull, and knowing when to start up again is important, highlighting the importance of actively keeping track of soil moisture to guide accurate irrigation management decisions.
ENSO and New Zealand water resources
El Niño and La Niña represent the two extremes of the El Niño–Southern Oscillation (ENSO), a naturally occurring fluctuation in Pacific Ocean Sea‑surface temperatures that typically operates on a three‑to‑seven‑year cycle.
The importance of irrigation performance checks.
Performance checks are also important to meet Farm Environment Plan requirements associated with your property land use consent, you need to demonstrate that your irrigation system is designed and operating efficiently.
Do your effluent ponds leak? How do you know?
Most dairy effluent storage pond owners believe that their ponds are not leaking, particularly those that have been synthetically lined.
Measuring Water to Manage it Well
From September 2026, all water takes greater than 5 litres per second will need to be measured and recorded every 15 minutes, and the data telemetered directly to the Regional Council.
Renewing Your Resource Consent
The article I wrote for the last Canterbury Farming publication generated much interest and feedback.
Renewing Consents
The end of 2025 brought news of a huge amount of proposed change in the resource management space – too much to cover in one article.
A New Chapter for Farming Resource Consents
The major overhaul of the Resource Management Act (RMA) introduces two replacement laws: the Planning Bill, focused on enabling development and land use, and the Natural Environment Bill, dealing with environmental protection and management.
Understanding Source Water Risk Management Areas (Drinking Water Supply Protection Zones) and What They Mean for Rural Landowners
Source Water Risk Management Areas (SWRMAs) are becoming an increasingly important part of New Zealand’s drinking water safety framework, and for rural communities in particular, they can have real and lasting impacts on how land is used.
Consents – they need your attention!
Consent renewal isn't automatic. Understanding what councils are looking for and getting your application right matters more than ever.
We got off lightly, this time.
In Canterbury we’ve been fortunate to have been spared from the drought conditions that have been experienced over the 2024/25 summer in the top of the South Island and parts of the North Island, although parts of North Canterbury have been very dry at times.
Leaky effluent ponds? Prove it!
One of the drivers for proving that effluent storage ponds are not leaking, is the need for farms to operate at a minimum of Good Management Practice (GMP). Ideally the farming operation should be operating at better than GMP.
Will your irrigation consent be renewed?
Consent holders are now frequently asking questions about the renewal process and whether it is going to be possible to renew their irrigation consent.