Water management

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Water management

Summer 2001 drought

In 2001, a one-in-24 year drought resulted in the Waimea River drying up almost completely, leading to severe water restrictions. In seven of the last 10 years, water rationing and restrictions have been required to manage the water resource while a more sustainable approach has been developed. Read the full story about the 2001 drought, the ‘Big Dry.’

Water take rules

In 2015, the Council introduced new ‘water-take’ rules intended to protect the natural values of the Waimea River, provide a more appropriate allocation of water and meet national guidelines for freshwater management. The new rules, which will come into effect in November 2018, introduce a minimum flow for the river to prevent it from drying up completely in times of drought.

Triggers for rationing

To make sure the minimum flow can be achieved, the water-take rules also introduced new rationing triggers for both rural water permit holders and urban homes and businesses.

If there is no dam, these rules will have a significant impact on residents’ way of life beginning in the summer of 2018. Additionally, the river flow will not be allowed to drop below 800 litres per second.

Average water used in common household tasks

Source: Combined data from BRANZ Studies in Auckland, Kapiti Coast, Waitakere Council and Metrowater.

Understanding summer water rationing for your household

Rationing for urban homes and businesses will also kick in earlier in dry periods and will be much harsher than in the past.

Without a dam, people in Richmond, Brightwater, Mapua or Redwood Valley (that’s 20,000 or so residents) will have to cut their water usage by 25 – 50% nearly every summer, with urban water rationing predicted in summer nine out of every ten years.

Dam benefits chart 2

At Stage 3 rationing – which happens about 50 days most summers – urban households will have to cut back by at least 25 percent, or to approximately 525 litres per day. (In summer, in Richmond, current household use is 700 litres per day.) That may mean giving up your shower or bath each day, or only doing a load of wash every third day.

Serious water rationing at Stage 5 will happen once out of every 6-10 years and last an average of 30 days. At this stage, urban households will have to cut water use by 80 percent, or a maximum of 140 litres per day. This means showers or baths every third day, flushing the toilet only once a day, and a load of wash once a week.


Daily urban water 'budget' (summer)

daily urban water budget

Rural water allocations and permits

Water permits have been reassessed to achieve an overall reduction in the rural water take. That has potentially catastrophic consequences for rural businesses’ ability to operate. Rationing for permit holders will kick in earlier in dry periods and be more stringent, making it difficult to grow crops, with serious consequences for Nelson Tasman’s economic health.

Water permits

The TRMP now defines two classes of water permits:

  • those “affiliated” to the dam where the holder has a water supply agreement (WSA) that is linked to discharges from the operation of the dam; and
  • those “not affiliated”.

Affiliated permit holders will have a very high security of supply. No rationing will be required for this category of permit holder unless there is a very severe drought that exceeds a 50-year probability.

For non-affiliated permit holders, the rationing is as for a ‘no dam’ situation, until the dam operates. From then onwards, the rationing regime is significantly more stringent. Triggers will result in reductions virtually every summer with “cease take” requirements potentially applying.

(New permits issued in 2017/18 will also have a new term of 20 years.)

Urban water supply

For the purposes of providing water to the urban region, Tasman District Council will become a water permit holder with a Water Supply Agreement (WSA), supplying water to urban households.


Rural water users on the Waimea Plains (typically irrigators) will have their own water permits and WSAs that are applied for and registered through Waimea Irrigators Ltd.

For irrigators and those considering not affiliating with the Dam scheme, there is more detailed information to read on the Waimea Irrigators Ltd website.

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