Irrigation Scheme Operation

Guidelines for the Operation of the Waimakariri Irrigation Scheme

The Waimakariri Irrigation Scheme, like most irrigation schemes, resembles an arterial system in that race sizes get smaller as side races are fed and water supplies are made. All of the races have been designed to carry the volumes required to supply the shares they service. The third and last upgrade of the scheme from 14000 to 18000 hectares was completed in 2002. No spare water will be available, in theory, in any race.

In total, the scheme has nearly 250 kilometres of irrigation race and it takes up to 48 hours for water from the Waimakariri River to reach those shareholders furthest from the intake. As a consequence, requests for water, or to cease supplying water, must take this lag time into account.

PLEASE NOTE

THE SALE AND TRANSFER OF SHARES IN WIL IS GOVERNED BY THE CONSTITUTION OF WIL. RESTRICTIONS MAY APPLY WHICH MAY RESULT IN A TRANSFER BEING REFUSED.

A full explanation of restrictions to the sale and transfer of shares is covered in the FAQ's section of this site. The Board recommends this is read closely for those wishing to sell or purchase WIL shares.

Ordering Water

When water is required water it must be ordered at least 48 hours ahead of the required time.

Requests for water should be faxed to the Race Manager on 03 313 0074 and must include the following information and

· Which property the water is for
· The start up time and date
· The stop time and date
· Flow rate

Which Property / Which Race

Water is only available to properties that have been formally identified by the shareholders and at a flow rate that matches their share allocations. All races have been designed for specific volumes and shareholders must take their ordered water entitlements from the designated location.

Start Up & Shut Down Procedures

At least 48 hours notice is required from Shareholders who wish to take, or cease taking water. This is required because it takes that amount of time for the water to travel through the system and reach all shareholders' properties. Shorter notice periods are possible in some cases with due regard being given to the lag times involved.

Volumes and Flow Rates

Each share entitles the irrigator to 0.075 litres of water per second per hectare. Shareholders may hold a minimum amount of 6 shares/ha (.45 l/s/ha), or 7 shares/ha (.525 l/s/ha), or 8 shares/ha (.6 l/s/ha) or a 9 shares/ha (.675 l/s/ha). The maximum number of shares that can be owned by any irrigator is 9 shares/ha with a corresponding flow rate of 0.6 l/s/ha which is the maximum that can be used in conformity with the Company's Resource Consent.

Continuous Supply

Because of the nature of the race system and the impossibility of managing a start/stop scenario, water must be taken as a continuous block. It is not uncommon for some farmers to start in the spring and continue irrigating right through until the autumn; perhaps their only break being a notified shutown.

Stop/start supplies, however, are difficult to manage. They often create unacceptable by-wash flows and can breach the conditions of our resource consents.

Because of this water flows are not available for daytime-only irrigation. Water will only be supplied continuously over a number of consecutive days and nights in any one week. Where very small volumes are involved it may be necessary for the irrigator to construct a holding pond from which their supplies are drawn as required. Smaller irrigators may need to form groups to help them achieve acceptable flow rates.

Monitoring Your Flows

All irrigators are required to measure the amount of water they are taking from the scheme. This must be done to the satisfaction of Waimakariri Irrigation Limited. This will involve the fitting of a flow meter that records the flows on an instant basis and accumulates volumes during the season. The measuring device must be recorded continuously to an accuracy of plus or minus 5 per cent.

Various systems exist for measuring water volumes including mechanical flow meters, pressure loggers, power use loggers, and different forms of measurement system that is best for you will depend on the on-farm irrigation system you install.

WIL has fitted at its own cost, flowmeters to all pumps that draw over 35 litres per second.

IMPORTANT SUMMARY NOTE FOR IRRIGATORS

• Water must be ordered at least 48 hours before it is needed.
  
• When water is no longer required, 48 hours notice must also be given.
  
• All notices regarding supply are best given by fax to Phill Reid at (03) 313 0074
  
• Contact Phill Reid if you have any problems on 021 570 544,
  
• or WIL on phone (0800) 855 559
  

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