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Manawatu-Wanganui region

Water Quantity

Every drop of water we take is one less for someone else who may need it or for the creatures who inhabit our waterways. Demand for water for agriculture, water supply and industry has more than doubled in our Region over the past 16 years, with the greatest increase occurring between 1997 and 2004.

Demand for water varies across the Region and in some places this demand has already reached or exceeded available volumes. These areas include the Upper Manawatu, Upper Whanganui and Oroua catchments as well as the Makakahi, Mangapapa, Tutaenui and Makara Water Management Zones.

Horizons' have one of the most comprehensive water metering programmes in New Zealand. All new consented surface and groundwater water takes must be metered and larger takes are required to return data on water use either manually or by telemetry. Our Region is well placed to meet national regulations around water metering and Horizons was used as a case study of best practice management in the development of these regulations.

Water quantity management is one of the core roles of Horizons Regional Council.

The Region has some of the most valuable water in the country. On average an estimated 4,752,000 m³ is taken per day for hydroelectricity generation – that’s enough to fill 1,901 Olympic-sized swimming pools. All of this water comes from surface water sources and more than half is exported to Waikato as part of the Tongariro Power Scheme. The remainder is used for smaller power schemes.

A further 1,340,228 m³ per day is drawn from the Region’s water sources for agriculture, industry and town water supplies. This is enough to supply the day-to-day needs of over 4.4 million people, irrigate 26,805 ha of pasture or fill just over 536 Olympic-sized pools. This has increased from 558,527 m³ per day in 1997.

The Horizons’ monitoring station on the Manawatu River in Palmerston North has the longest continuous flow record in the country. They currently monitor:
• Rainfall at 46 sites;
• Continuous river level/flow at 65 sites;
• Soil moisture at nine sites;
• Water use at 281 sites;
• Groundwater level at 138 manual and 19 automated sites.

Horizons also processes up to one thousand manual measurements of river flow every year. Up-to-date information is available online via the Rivers and Rainfall and WaterMatters section on Horizons’ website.

Key issues for water quantity in the Region include:
• Demand versus availability;
• Impacts of water takes on river health, fish and other aquatic species;
• Impacts of groundwater takes on rivers and lakes; and
• Salt water intrusion.

Regional Summary
Water quantity data in this region

Regional councils collect information about how much water is available and manage resource consents for those wishing to take water from rivers or groundwater supplies. Use the buttons below to view regional information on: how much water is available, where it comes from and how its used.


Rainfall {{waterAvailable.rainfall}} Runoff to sea {{waterAvailable.runoff}} Groundwater available: {{waterSource.groundwater}}
{{waterSource.groundwaterPercentAvailable}}% of total available
Surface Water available: {{waterSource.surfacewater}}
{{waterSource.surfacewaterPercentAvailable}}% of total available
Town supply
  • How much water is there in this region?

    Rainfall and runoff in this region

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    Rainfall and runoff

    Relative Volume Source Volume
    Rainfall total:
    {{waterAvailable.rainfall }}
    rainfall Rainfall Total {{waterAvailable.rainfall}}
    Runoff total:
    {{waterAvailable.runoff }}
    runoff Runoff to sea {{waterAvailable.runoff}}

    The table above shows the average amount of rainfall the region receives each year and how much of that flows out to sea. These are approximate figures only.

  • Water consents: where does water come from?

    The split between surface water and groundwater

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    Consented water by source

    Relative volumes
    Amount available to consent Surface water:
    available to consent
    available to consent
    Volume consented Surface water:
    volume consented
    volume consented
    Source Amount available to consent Volume consented Consented as a percentage of available
    surface water ground water {{item.source}} {{item.amountAvailable}} {{item.volumeConsented}} {{item.percentageConsented}}
    {{}} {{}} {{}} {{}}

    The table above shows how much water is available to use compared with the amount that is actually consented for use. It also shows how much of this water is surface water and how much is groundwater.

    Total groundwater allocation is calculated as Daily Max Volume over 100 days for irrigation takes and Max Daily Volume over 365 days for all other uses. 

    Total surface water available to allocate is underestimated as there are some sub-zones where there is there is little to no hydrological or ecological information to enable a limit to be defined. Although it appears there is plenty of surface water to go around it is important to talk to Horizons as it is not available everywhere.


  • Water consents: How is water used?

    Consents by use in this region

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    Annual consented water use by type

    Overall annual volume for {{waterAvailable.year}}
    Relative breakdown
    Activity Percentage of total consented Total volume Number of consents
    {{item.displayText}} {{item.displayText}} - - No data available {{item.breakdownPercentage}}% {{item.totalVolume}} {{item.numberOfConsents}}
    Total {{}}% {{}} {{}}

    The above table shows the proportion of water consented for irrigation, industrial, stock, town supply and other. It excludes hydro electricity. In this region/management zone {{hydroUsage.totalVolume}}/year is consented for hydro-electricity and makes up {{hydroUsage.percentageConsented}}% of the total water volume consented for this region/management zone

    The water used for hydroelectricity generation in this region is considered to be some of the most valuable water in the country. On average an estimated 4,752,000 m³ per day is taken for hydroelectricity generation in this region. All of this water comes from surface water sources and more than half is exported to Waikato as part of the Tongariro Power Scheme. The remainder is used for smaller power schemes.

Surface Water Zones Groundwater Zones