After the Project Aqua Proposal was withdrawn, the Waitaki Catchment Amendment Act was implemented to resolve conflicts over access to water from the Waitaki River into the future. A new Statutory Plan would determine the bulk allocation of water for the 3 main activities in such a way that would maximise the benefit to the nation and local communities.  The final plan allocated a "hydro-generation" block of water at flows above 230cumcs, an "irrigation" block at flows between 150 - 230cumecs and an "environmental" block at flows below a 150cumec minimum that would maintain instream amenity and ecological integrity.

What is the nature of the change?

Figure 1 below is a schematic diagram illustrating those broad allocations and how they might be impacted by the naturally varying river.  The squiggly line represents the hypothetical fluctuating flow regime in the river over time.  In the Waitaki the river flow is entirely regulated in all but large flood flows so actually the flow is just the tailwater released by Meridian for optimum power generation. 
The figure also has on it the mean flow of the river at 380cumecs, the default minimum flow of 80cumecs that existed prior to the development of the Plan.
The graph also shows two occasions when the flow in the river  drops below 230cumecs.  Should irrigators be using the full irrigation allocation at those times (i.e. 80cumecs) there are two options to make up the "shortfall"
1.    Meridian provide the extra water required from stored water in the lakes or
2.    the irrigators take the extra water they require from the environmental block so that Meridian do not have to release any extra water for the irrigation (see two blue tongues below 150cumecs marked "deficits").

Figure 1: Concept of water allocation blocks in relation to river flows

The Commissioners who developed the Waitaki Catchment Water Allocation Plan decided the first option was the optimum compromise between all the river interest groups and river values in the best interests of the nation. 

Now the Proposed Plan Change 3 is to change the rules to reverse that so the second option prevails.  Should the shortfall be large the irrigators will be able to keep taking water down to a new minimum of 102cumecs for up to 10 consecutive days, followed by a recovery period of 2 days. This is in effect a direct transfer of water from the local environmental allocation to Meridian Energy for generation.

How necessary is this change?

Figure 2 below shows from real historical data that for mean monthly flows, Meridian has the volumes of water to provide 100% reliable irrigation (up to a maximum of 80cumecs) over and above a minimum flow of 150 cumecs. 

Accordingly, the Society seeks 100% reliable supply block from Meridian for all main stem irrigators grouped above 150 cumecs so that priority irrigation rights within it would be of no material significance to individual irrigators.  Figure 2 shows is this is perfectly feasible.  Legal issues around retaining "priority access" for earlier consent holders are thus resolved as all irrigators effectively get "first priority" rights.

Figure 2:  Actual monthly flows since 1980 compared to seasonal water demand over a minimum flow of 150 cumecs

It may not be possible to implement this until 2025 when Meridian Energy's consent for discharge over the Waitaki Dam comes up for renewal.  But such a delay is not an issue as the above hydrological analysis indicates that in the meanwhile irrigators are not at any significant risk.

The real issue

In appendix 3 of the s32 report under "Waitaki" it says "The major issue is how existing consents to take water will be addressed given the conditions of the new consents i.e. those granted after the Plan became operative".

So if we are in this predicament because of an error in the conditions on new consents then the problem should be addressed by changing the consent conditions not by lowering the minimum flow on the river. 

Essentially, the threat of water shortage is being used by Ecan as a reason to change the Plan when it is really to avoid a legal stouch between them and the farmers over priority access.  We don't believe this is a right, just or wise reason to change the flow regime for all time and further undermine the resilience of the river.

What you can do

If you are concerned about the lowering of the minimum flow then the best thing is to submit to the Plan Change by the 22 August 2014.  If you are on the internet you can find the submission form at the Ecan Website or ask them to send you one.

The Society plans to outline the issues and how it might be resolved at their AGM at the Waitaki Bridge Hall on Wednesday 13 August 2014, at 7.30pm.  Submission forms will be available there.
For further information contact Ian McIlraith, Chairman.