New report reveals extent of water abstraction in Canterbury
A new report gives us the best understanding yet of how much water is being used in Waitaha/Canterbury.
The Canterbury Region Consumptive Water Abstraction Report (PDF file, 6.42MB) covers the period between 2014-2021 and uses data from water abstraction points across Waitaha.
Significant improvement in water abstraction data
The report found a significant improvement in the quality and quantity of measured data in the period from 2014-2021.
We received data from as many as 80 per cent of water abstraction points in the 2020/21 water year, a marked increase from 61 per cent in the 2014/15 year.
While the consumptive water abstraction report gives us a clearer picture of how much allocated water is being abstracted, it did not attempt to quantify the effect of this abstraction on the environment.
The new data plays a crucial role in allowing us to manage water resources effectively and efficiently while ensuring compliance with national regulations and consent conditions, especially as we work towards notifying a new Land and Water Regional Plan over the coming years.
We expect that further gains in data reliability will continue as the Resource Management Act rules on water measurement and reporting passed in 2020 are progressively rolled out until 2026.
Water use not the same as water allocation
The report revealed that while consented allocation can shed some light on water use in Waitaha, the volume of water abstracted is only a small fraction of the total consented allocation. In 2020/21, the volume of water abstracted through measured takes was only 19 per cent of the total volume allocated.
The Rangitata River is the only catchment where more than 30 per cent of allocated water is currently abstracted. Typically, more than 80 per cent of the annual consented volume is taken. This is principally because the Rangitata Diversion Race can continue to take water for hydroelectricity generation outside of the irrigation season.
In the 2020/21 water year, more than 3636 million cubic metres of water was recorded as abstracted from Waitaha surface and groundwater sources. That's enough to fill around 1.45 million Olympic swimming pools or cover Christchurch to a depth of 2.5 metres. This figure does not include around 20 per cent of abstraction points not measured, nor permitted activity takes, which tend to be smaller in volume and do not require reporting.