Executive Summary
This report summarises the results of the 2006 survey of water take consents for consumptive use (including drinking water supply, industry, irrigation and stock water supply). It follows on from and updates a similar survey in 1999. It also draws on information from work in the intervening years; national water accounts, agricultural census (2002) and monitoring of surface-water flows.
Number of consents
There are currently close to 20,000 consented water takes in New Zealand. The majority of coldwater consents are taken from groundwater (66%), with 29 percent from surface water (run-of-river), 3 percent from storage (dams and lakes) and 2 percent from geothermal sources. Irrigation accounts for the greatest number of consents (78 percent) followed by industry (11 percent) and public water supply (9 percent). While stock water supply accounts for only 2 percent of consented takes, it should be borne in mind that the vast majority of takes for stock water are non-consented as they fall within permitted activity and/or reasonable use criteria.
Figure ES-1: Consents (number) by source
Text description of figure:
| Consents by source | Percent |
|---|---|
| Groundwater | 66% |
| Surface water | 29% |
| Storage | 3% |
| Geothermal | 2% |
Figure ES-2: Consents (number) by use
Text description of figure:
| Consents by use | Percent |
|---|---|
| Irrigation | 78% |
| Industrial | 11% |
| Public | 9% |
| Stock | 2% |
Volume of water allocated
Nationally the total allocation rate is 679 cubic metres per second (m3/s), equal to about double the average flow rate of the Waikato River. Two thirds of this allocation is from surface-water sources (run-of-river and storage) and a third from groundwater. Irrigation accounts for 77 percent of allocations, public water supply for 11 percent and industrial use for 9 percent.
Figure ES-3: Distribution of allocation (m3/s)
Text description of figure:
| Distribution of allocation (m3/s) | Percent |
|---|---|
| Surface water | 60% |
| Groundwater | 33% |
| Storage | 6% |
| Geothermal | 1% |
Allocation from source:
- Surface water (run-of-river) 60%
- Groundwater 33%
- Storage 6%
- Geothermal 1%
Allocation by use:
- Irrigation 77%
- Public 11%
- Industry 9%
- Stock 3%
Regional distribution
Figure ES-4:Regional water allocation (m3/s) by source
See
figure at its full size (including the text description).
Canterbury: 55% (373 m3/s)
- 56% surface water
- 43% groundwater
Otago: 18% (125 m3/s)
- 88% surface water
- 6% storage
- 6% groundwater
Others: 27% (177 m3/s)
- 48% surface water
- 17% storage
- 35% groundwater
Allocation trends
Nationally, water allocation increased by approximately 50 percent between 1999 and 2006. The figures below show the increases in allocation by council.
- Allocations increased by less than 50 percent in: Auckland, Canterbury, Hawkes Bay, Otago, Northland and Taranaki.
- Allocations increased by more than 50 percent in: Bay of Plenty, Southland, Waikato, Gisborne, Greater Wellington, Manawatu-Wanganui, Marlborough and Tasman.
Figure ES-5: Regional water allocation (m3/s) 1999 and 2006
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figure at its full size (including the text description).
Annual allocations
The total annual allocation is close to 10 billion cubic metres per year (Bm3/y) which is equivalent to about 17 percent of the volume of Lake Taupo. This is just over 4 percent of the annual water balance (as per National Water Accounts). As indicated in the figure below, the annual allocation as percent of the annual water balance varies between regions. In the regions with high irrigation and/or drinking water demand (Canterbury, Otago, and Wellington), it is greater than 10 percent.
Figure ES-6: Annual allocation as percent of annual water balance
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figure at its full size (including the text description).
Surface-water allocations
The study included determination of allocation of surface water takes as a percent of mean annual flow and mean annual low flow.
The figure to the right shows allocation as percent of mean flows (per catchment). While there are some limitations to the approach (due to monitoring site locations), it does show relative pressure on catchments. It shows high levels of allocation for major catchments on the east coast of the South Island, particularly in Canterbury and Otago.
Figure ES-7: Allocation as a % of mean annual flow
See
figure at its full size (including the text description).
Consented irrigated area
- Total consented irrigated area is 970,000 hectares.
- The majority of the area is in Canterbury (66 percent) and Otago (14 percent).
- As indicated below, 75 percent of the area is in arable crops and pasture.
Figure ES-8: Consented irrigated area crops (%)
Text description of figure:
| Irrigated crops | Percent |
|---|---|
| Arable | 43% |
| Pasture | 31% |
| Other | 20% |
| Horticulture | 5% |
| Viticulture | 1% |
The area increased by 55 percent over that reported in the 1999 survey (600,000 hectares). The figures below show the growth in consented irrigated area for the 16 councils. The apparent decrease in consented irrigated area for Northland, Auckland and Gisborne reflects tightening of consenting and recording processes.
Figure ES-9: Consented irrigated area (ha) 1999 and 2006
See
figure at its full size (including the text description).
Water use
Water use as a percent of allocation within catchments and groundwater zones varies during and between years. This study presented a number of case examples which show an upper use of 80 percent of allocation but ranging down to 20 percent. The variation in percent of use reflects the variability of demand but also highlights a constraint to the current consent process which is based on a high level of supply reliability. The figure below is an example of water use from the lower confined aquifer on the Waimea Plains, Tasman District. It shows weekly water use as percent of allocation for three irrigation seasons (2000/01, 2003/04 and 2005/06).
Figure ES-10: Water use Waimea Plains - lower confined aquifer
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figure at its full size (including the text description).
