The Need

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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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River health

The Waimea River flows from where the Wairoa meets the Wai-iti near Brightwater, into Tasman Bay near Appleby. The river feeds the area’s aquifers and groundwater, providing water to homes and businesses.

The aquifers are the Nelson Tasman region’s natural, low-cost water storage system. Normal river flows keep these natural storage systems charged and full, which secures a supply of water for urban and rural needs at the same time that it maintains a healthy river ecology.


A healthy river is critical for the sake of the environment, to protect the community’s drinking water supplies, and so it can be enjoyed safely for fishing, swimming and other recreation.

How the dam would help the river

The Waimea Community Dam would release water into the Waimea River in times of low flow to supplement the natural river flow and ensure a healthy river ecosystem. With the dam, the minimum flow in the river will not drop below 1,100 litres per second. That will result in a healthy river, maintaining natural, cultural and recreation values.

Under a no-dam scenario, the minimum river flow allowed will be 800 litres per second to protect our aquifers from the threat of saltwater intrusion contaminating our drinking water supply. However, it does not protect the natural ecosystem of the river and is unlikely to meet the national freshwater standards. The consequences of that may be that the Council is forced to consider even greater water use cuts when our planning rules are up for review again in 2025.

Click here for more information on saltwater intrusion.

Meeting requirements

The Government’s National Policy Statement for Freshwater Management sets out requirements for maintaining freshwater quality that the Council is required to meet. Based on a recommendation by water ecologists at Cawthron Institute, a minimum flow of 1,100 litres per second is the best, lowest flow possible that would still maintain the river’s health. It is expected that this minimum flow will meet the objectives of the national requirements.

Freshwater Investment Fund $7 million grant will boost biodiversity

The Waimea Community Dam project will receive a $7 million grant from the Government’s Freshwater Improvement Fund. The grant is recognition the dam will improve the health of the Waimea River and biodiversity in the surrounding area.

The money can only be used for the capital costs of the dam related to improving freshwater quality and biodiversity. Collectively, the work funded will provide a significant investment for native biodiversity and indigenous ecosystems on both public and privately-owned land.

In addition to the Dam creating a new minimum flow in the Waimea River, some of the other biodiversity / environmental benefits of the project are:

  • The salvage, propagation and establishment of at least three new populations of the nationally rare plant New Zealand shovel mint. New Zealand Shovel Mint, Scutellaria novae-zelandiae and also known as NZ Skull Cap, is only found in the Nelson-Tasman and Marlborough regions. It is a threatened species and nationally critical. The soft woody herb grows up to 30cm tall and has creeping stems, small dark green oval leaves, and hairy white flowers appearing August to March.
  • Re-creation of extensive tracts of rare lowland alluvial native forest in the Waimea River Park through native tree plantings Waimea River Park will have extensive native plantings along its berms to re-create rare lowland alluvial native forest as part of the dam biodiversity programme. The Park covers about 394 hectares of land alongside the Waimea River. In the past the area has been managed by the Council primarily for river control and soil conservation. However, TDC is in the early stages of a significant development plan for the area to enhance conservation values, preserve historic sites, and provide for greater public access and recreation.
  • A pest management area in the upper Wairoa Gorge in partnership with DOC to conserve and enhance populations of a rare land snail (Wainuia nasuta).The land snail Wainuia Nasuta is a carnivorous land snail and a threatened species. Its shell grows up to 31mm in diameter and it is found in the northeast part of the South Island.
  • Restoration of a nationally-rare freshwater coastal wetland on Rough Island, including improving protection to rare or uncommon plant species
  • Investment in weed control in the upper Wairoa Gorge Conservation area, particularly to curb Old Man’s Beard and allow native forest to regenerate
  • Three other rare plant species transplanted into new sites in the Wairoa Gorge conservation area, ensuring the species persist in the Lee River catchment near the dam and reservoir site

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Regional economic prosperity

The Waimea Plains holds some of the most fertile productive land in the South Island, producing fruit, vegetables and boutique crops such as hops and grapes. It is of national strategic importance and its loss of productive capacity would be significant.

The Dam is expected to bring growth in higher value crops and, therefore, increased economic activity and value to everyone who lives in the region.

Waimea plains

Unlike many other areas of New Zealand, the Waimea Plains are not dairy intensive and the Dam is the only large irrigation project that is not dairy-focused. Rather, the Dam will use nature’s infrastructure to keep the river healthy and recharge the aquifers that irrigate our high value crops. The project is a strong contributor to the regional economy and the health of the river without causing negative side effects generally associated with other irrigation projects.

Nelson Tasman businesses need water security to keep and grow their workforce and plan business growth. Without it, many small and medium businesses in the region will be forced to reduce operations or close down and the jobs they provide will be lost. Summer water rationing and reduced water allocations will affect all business on the Plains and dramatically affect the regional economy today and in the future.

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Community supporters

“Council’s partnership approach has made the dam the most cost-effective solution to the region’s water shortage. It allows us to solve four issues with one, cost-effective, solution – urban and commercial water shortage, river health, meeting the social and recreation needs of the community and preventing salt intrusion into our drinking water supply.”
— Tasman District Council Mayor Richard Kempthorne (TDC media release)
“We see this project as essential to secure the future prosperity and sustainability of our fantastic and vibrant region.”
— Waimea Nurseries Director Bruno Simpson (
“I think the Waimea Community Dam is a no-brainer. We collectively, as a community, need to do all we can to get it over the line… It is inconsistent with Nelson’s strong environmental brand that water quality gets so bad in summer that it can kill dogs. The only practical solution is the Waimea Community Dam that will store water during high floods and replenish the river during summer.”
— Minister for the Environment and Nelson MP Dr Nick Smith (

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