IRRIGATION
The drying of our spring-fed streams is mainly caused by a huge increase in water takes by large inland dairy farms, added to the smaller effects of taking water from aquifers closer to the coast, plus a series of relatively dry winters.
Yet Environment Canterbury (Ecan) is still receiving applications from farmers for permission to take more water. Ecan has brought in a zoning system but it is based on a very incomplete understanding of the underground network of aquifers. Also, Ecan doesn’t know how much water is actually being used because it is not measuring water usage.
Irrigation in Canterbury is on a very big scale:
- Peak allocation of water for Canterbury is equal to 180 times the flow of the Avon River (290 cumecs, or cubic metres per second).
- Most of this water is used for irrigation (80%).
- Two big irrigated dairy farms use more water than the whole city of Christchurch
- More than half of all NZ water use is in Canterbury (58%).
- Most of NZ’s irrigated land is in Canterbury (70%).
In the next ten years the use of water for irrigation is projected to double. Where’s all that water going to come from? It’s more than the total combined flow of our two biggest rivers, the Waitaki and Rakaia. Does this sound as though we’re heading on a sustainable path of development?
OVER-ALLOCATION
A big part of the problem is over-allocation, which means letting the water-users take too much.
Anyone wanting to take water from wells or rivers needs a resource consent, issued by Ecan. Unfortunately Ecan is not managing our water properly. In some places, Ecan has even allocated more water that actually exists!
Farmers on the Canterbury plains used to farm mostly sheep. They used to just take artesian water for home use and for stock to drink. Then some started using it for irrigation so they could grow crops and farm dairy cows. They took some of this water from rivers, some from wells.
Gradually the dairy farmers got Ecan to let them take more and more water. Soon they were taking so much that rivers began drying up. Soon the water was not flowing freely from wells any more, and they had to start pumping it up. This made the water level in the aquifers fall even more. Then they had to drill deeper wells and have more powerful pumps that use enormous amounts of electricity to bring the water to the surface.
By this time, they were taking water out of the aquifers faster than it could be naturally replenished. Springs that used to be fed from the aquifers stopped flowing and the spring creeks dried up. More streams are shrinking or drying up all the time.
INCREASING POPULATION
Of course town and city dwellers use water too. But irrigated farming takes the lion’s share of our water – 80% of it. If the population of Christchurch doubled, it would only use as much water as two more large dairy farms. And new dairy farms are still springing up all the time.
While town and city dwellers put up with water restrictions during the hot summer months, big corporate-owned dairy farms go on using water that belongs to everyone, as fast as they can suck it up out of the ground or drain it out of our rivers. The more of our water they take, the bigger their profits.
THE 'DOUBLE WHAMMY'
Intensive farming hurts our environment not just once but twice – a ‘double whammy’. This is because more animals mean there is more fertilizer, urine and dung on the land than there used to be.
When it gets washed into the ground and streams, there is less water to dilute the pollution. So the pollution is more concentrated.