WHAT IS THE CRITICAL CHANGE PROPOSED FOR THE LOWER WAITAKI RIVER IN ECANS PROPOSED PLAN CHANGE 3?
the Project Aqua Proposal was withdrawn, the Waitaki Catchment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
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.
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
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
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
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
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
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
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
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
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.
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.