Water take rules are changing in November! Do you own water shares?

WIL has a word of caution for water users: the amount of water available to you is changing later this year. Without the Waimea Community Dam, in dry months it is highly likely landowners will have a cease take instruction. If the Waimea Community Dam moves forward but you don’t have water shares through WIL, you are also very likely to have a cease take instruction in dry months.

Starting November 2018 (under the with-Dam scenario), Step 2 restrictions (2,300 l/s at the Irvines/Wairoa Gorge recorder) will mean a 50 percent cut to water use and Step 3 restrictions will mean complete cease take for unaffiliated permit holders. Based on historical flow data, the Wairoa river falls to 2,300 l/s most years. 

Step 1 - Wairoa River
< 2,750 I/s
Step 2 - Wairoa River
< 2,300 I/s
Cease Take - Wairoa River < 2,050 I/s
Allocation after bona fide permit review (m3/week) Allocation under 20% rationing (Allocation x 0.8) Allocation under 50% rationing (Allocation x 0.5)
3,500 2,800 1,500 0

Of course, anyone with water shares can affiliate those shares to access water from the Dam. If you don’t yet own shares, consider the following:

How would last year’s ‘big dry’ have affected me if the pending rules had been in place? 

One way to understand what may be in store is to cast your mind back to the end of last year – the ‘big dry.’ Water restrictions were in place throughout the region.

What if the new water take rules were in place during the big dry of 2017? See the figures below, which were presented to Tasman District Council's Environment and Planning Committee on 8 February.

Rationing was in effect for 28 days and irrigators were cut to 35% of their existing allocation for 14 of those days.

Under the new rules, the cut would have been 50% of the bona fide allocation for 19 days, for unaffiliated permit holders in a with-dam scenario. The flow at the Wairoa at Irvines gauging site was 2,200 l/s on 26th of December – had it dropped to < 2050 l/s a cease take would have been in place.

Without the dam, under the new rules all permit holders would have been cut to 50% of their bona fide allocation for 4 days.

Under the new rules, the takes can only recommence when the 7-day moving mean flow at the Wairoa at Irvines site rises above 6000 l/s. In other words, a substantial fresh (i.e. more than 10,000 l/s) would need to occur in the Waimea River before taking could resume.

Wairoa at Irvines No. of days below trigger flow
Consultation Days < 3000 I/s 33
Stage 1 (20% cut) Days < 2750 I/s 30
Stage 2 (50% cut) Days < 2300 I/s 4
Waimea at Appleby No. of days below trigger flow
Stage 4 (70% cut) Days < 800 I/s 0
(minimum flow reached was 911 I/s)
Option 2 - WITH DAM (for non-affiliated consent holders)
Wairoa at Irvines No. of days below trigger flow
Stage 1 (20% cut) Days < 2750 I/s 30
Stage 2 (50% cut) Days < 2300 I/s 19
Cease Take (100% cut) Days < 2050 I/s 0

Risk and extreme events

We’ve recently experienced two extreme natural events. 

Dr Morgan Williams, local Richmond resident and ex Parliamentary Commissioner for the Environment for 10 years, says that decades of research on our societal responses to the risks of extreme natural events is often to delay agreement on measures to reduce impacts. 

We continue to see the risks of necessary actions as bigger than the outcomes of the natural events themselves, even when the risks they pose are large, systemic and intergenerational – thus affecting many parts of our society, economy, communities and business.

The common element is that the risks are something that is seen as ‘tomorrow’ (not our worry) and the solution has costs or risks that are perceived as bigger (in terms of likelihood or impact on our selves) than the much larger systemic risk needing our attention.

In simple terms this is at the heart of the debates about the Waimea Community Dam. The risks that the dam addresses (security of supply in droughts and maintenance of river flows) are large, systemic, infrequent (but likely to increase in severity), intergenerational and driven by the single biggest risk humanity faces – our changing climate.

SH6, Rocks Road – Nelson City Council Facebook page, 1 February 2018.

The global risks landscape

Extreme weather events top list of risks

What is the impact and likelihood of global risks? Cyclones Fehi and Gita were more evidence of our region’s changing climate: wetter wets, drier dries. The World Economic Forum recently shared a risk analysis that showed risks with the greatest likelihood and impact are extreme weather events. For Nelson Tasman, that means more flooding, droughts and coastal inundation with bigger storm surges.

These risks bring worldwide concern about the security of freshwater supplies. Read the full report here.