Ten years ago, there were almost none of the big water sprayers that can now be seen on the Canterbury plains.
Farmers add fertiliser and sometimes spray cowshed effluent on the ground as well. All this stimulates the growth of grass and increases the productivity of the land.
WELLS
Much of the water you see being sprayed about comes from wells. Some of them go down hundreds of metres. The only way to bring water up from that depth is to have a pump down the bottom to push the water up. You can’t suck water up from so far down. These pumps use huge amounts of electricity. Some dairy farms have power bills of hundreds of thousands of dollars per year.
RIVERS
Irrigation races are cleverly designed to feed water over large areas of farmland. They slope downhill just enough to keep the water flowing to where it’s needed, up to 50 km away. The races branch into smaller channels, then into small ditches through farm paddocks. The water they spread on to the land comes from rivers such as the Waimakariri, Kowhai, Ashley and Hurunui.
THE REAL COST OF IRRIGATION
This water comes at an environmental cost which the users don’t pay. The effluent soaking into the ground is contaminating the shallow aquifers where everyone’s drinking water comes from. Some aquifers are being pumped dry faster than rain and underground flow can replenish them. This means our dried-up streams are going to stay dry unless we do something to reverse the process.
The Kowhai River used to be an important spawning river for salmon – not any more! Some years the Ashley dries up in places during summer. And the Selwyn River was once regarded as the best trout stream in the world with annual spawning runs in excess of 40,000 trout. Today that doesn’t seem imaginable, with 87 trout being counted during the 2005 spawning run.
LAKE ELLESMERE - A 'SHOCKING' EXAMPLE
This big coastal lake once had world-wide status for biodiversity and cultural significance. Now it has been recently described by an Environment Court Judge as “eutrophic, green in colour and seems devoid of any riparian management.” Describing the lake and the streams flowing into
it, the Judge also said that the Court was “shocked at the ever present effluent smell from
all these waterways and the clear evidence of
poor management, effluent levels and contamination.”