Central Plains Water Ltd Central Plains Water Ltd

Our story.

Switching irrigation water sources to provide a more environmentally sustainable solution for Canterbury’s agriculture.

Over the past century, the Canterbury region has developed as one of New Zealand’s most important agriculture, cropping and seed production regions, proudly underpinning Canterbury’s identity, and the nation’s economy.

Our world-leading food and fibre products are internationally sought after and with New Zealand’s population predicted to grow to just under six million by 2030, this demand will only increase. To meet that demand, farmers and growers need access to irrigation to enable the production of food and fibre our population will require. Without this, as demand increases prices will also increase, resulting in more imports to fill the food gaps. Water is the limiting factor.

Even the best farming systems are limited by soil moisture and the reliability of seasonal rain does not suffice in scaling up food production. Our rural areas that sit at the foot of the Southern Alps are likely to become some of the country’s drought hotspots, having already experienced two seasons of droughts in 1988/1989 and 1997/1999.

The Central Plains Water (CPWL) story began in 1883 with talk of establishing an irrigation scheme to service farms on the Canterbury Plains, with the first approach to central Government made by the then Malvern County Council. However, it wasn’t until 51 years later that the idea gained significant momentum.

Stage 1.

Located within the Selwyn District Council boundary, between the Southern Alps, SH1 and the Waimakariri and Rakaia Rivers. Stage 1 of the scheme was the largest irrigation project ever undertaken in the South Island. Opening in 2015 with an investment of $157 million, the project saw 13 bridges, 12 pump stations and 130 kilometers of underground pipeline constructed. Successfully switching irrigation from groundwater abstraction.
In early 2014, the construction of stage 1 saw irrigation delivered to 23,000 hectares of productive farmland in an area bordered by the Hororata and Rakaia rivers, introducing 300 million cubic metres of low-nutrient alpine water into the catchment to replace groundwater abstraction.

  1. The Rakaia River intake is located approximately 8 kilometres downstream of the Rakaia Gorge Bridge.
  2. Before entering the main headrace, the intake water is conveyed into flow control structures and sediment retention ponds and passes through a fish screen.
  3. A 17-kilometre-long canal delivers water from the Rakaia River into a piped distribution network.
  4. The terrace headrace was constructed with an engineered fill embankment ‘bench’ rising to around 15 metres before water enters a bench cutting into the terrace race for the remainder of its length.
  5. The headrace travels north for approximately 10 kilometres through to Leaches Road, following the most practical route through farmland.
  6. A piped reticulation system, controlled by a central computerised control system, distributes water to the stage 1 area, providing water to the farm gate at a pressure equivalent to a head of 40 metres.
  7. Since the completion of stage 1 construction on 1 September 2015, the scheme has delivered water 24 hours a day, seven days a week during peak irrigation season.

 

Schemes Stage One

A 17-kilometre-long canal delivering water from the Rakaia River into a piped distribution network.

Schemes Stage One
Schemes Stage One

Stage 2.

Located between the Selwyn and Waimakariri Rivers, with a total construction cost of $182 million stage 2 was the largest dryland conversion in the scheme, significantly helping to alleviate pressure on the aquifers critical to Canterbury. Stage 2 saw the installation of 12 pump stations, 3 pressure-reducing stations and a 23 kilometre long, subterranean large-diameter (2.5m) Glass Reinforced Plastic (GRP) pipeline.

  1. With an area approximately twice the size of stage 1, stage 2 provides the infrastructure for shareholders to switch from groundwater to low-nutrient alpine-sourced water to replenish flow in the lowland streams.
  2. Supported by consented and stored water from Lake Coleridge, stage 2 is entirely an underground gravity-fed pipeline distribution network utilising run-of-river water from the Rakaia River, supplying pressurised water to the farm gates – no on-farm water pumping.
  3. Since the completion of stage 2 in 2018, an additional 20,000 hectares of irrigated land has been achieved between the Selwyn and Waimakariri Rivers.
Stage Two
Stage Two
Stage Two

Sheffield.

Sheffield, covering approximately 4,600 hectares commenced operations in November 2017. Physically separate to stages 1 and 2, built to supply irrigation water, stock water and water for firefighting from the Waimakariri and Kowai Rivers (which are subject to similar low flow restrictions to those applying on the Rakaia River). With an investment of 42 million dollars, construction included a 2.5MW pump station, 2 million cubic metre storage pond and 37 kilometres of pipeline, helping to provide storage during periods when run-of-river abstraction is restricted.

  1. The river intake is located on the Waimakariri River opposite the Kowai River.
  2. Water from the Waimakariri River enters the intake channel where it passes through a rockfish screen and onto the sediment retention pond.
  3. The pump station transfers up to 2 cubic metres per second of water 80m vertically into an open channel supply race, through three concrete drop structures to slow velocity before it enters the 1.6m inlet pipe for the last kilometer to the storage pond.
  4. The Sheffield storage pond is approximately 100 acres in size and holds 2.15 million m3 of water. The pond is lined with 300,000m2 of high-density polyethene to stop any losses through the mainly gravel pond floor.

 

Schemes Sheffield

The 2.15 million m3 Storage Pond delivers 4mm/day of water at a target minimum pressure of 3.5 bar to individual farms.

The road to climate resilience.

135 years after Malvern Country Council made the first approach to central Government, CPWL has realised its vision. We’re now bringing irrigation to the Central Plains of Canterbury, delivering environmental, economic and social benefits to the wider community by increasing Canterbury food and fibre production for local and world markets.

1883 - The beginning

The first approach about an irrigation scheme is made to Central Government by the then Malvern County Council.

1934 - Scheme exploration

The Government begins to explore large-scale irrigation in Canterbury and Central Otago, the two driest regions in New Zealand.

2000 – The early years

The Central Plains Water Enhancement Scheme Steering Committee, a joint committee of the Christchurch City Council and Selwyn District Council, was established.

2003 - Establishment of CPWL

Central Plains Water Limited (CPWL) was established in 2003 to implement and operate the scheme, in 2004, CPWL issued a prospectus to raise funding to support the consenting process.

2012 – Design begins

CPWL received a $5 million loan from the Selwyn District Council to progress to detailed design work of the scheme on stage 1 with a further $5.7 million coming from the Ministry for Primal Industries Irrigation Fund.

2013 – Stored water solution

A way forward in securing a reliable solution for water storage was found when the Government accepted Environment Canterbury’s recommendation to change the Water Conservation Order covering the Rakaia River, allowing the release of water from Lake Coleridge for irrigation when the river is low.

2013 – Consents granted

The Trust was granted resource consents from Environment Canterbury and Selwyn District Council to construct and operate the Scheme.

2014 – Construction Stage 1

Utilising run-of-river water from the Rakaia River, supported by stored water from Lake Coleridge, supplying water for irrigation to the farm gates of 23,000 hectares of land, Stage 1 commenced in 2014. Consisting of 17 kilometres of canal, 130 kilometres of pipeline, 13 bridges and 12 pump stations, delivered in 2016 - on time and budget, construction costs $157 million.

2015 – Best practice agriculture

Farmer shareholders enter into Water Use Agreements covering the supply of water and Farm Environmental Plan requirements to be part of the scheme.

2015 - Award-winning

CPWL won the Champion Canterbury Supreme award and the Champion Canterbury Infrastructure/ med/large category award. These awards recognised the excellence, innovation, and success of businesses.

2016 – Construction Sheffield

Utilising run-of-river water from the Waimakariri River, supplying water for irrigation to the farm gates of 4,400 hectares of land, Sheffield consists of a 20 hectare reservoir (storage pond), 37 kilometres of pipeline, and 7 pump stations delivered in 2017 on time and budget, construction cost $42 million.

2017 – Construction Stage 2

Utilising run-of-river water from the Rakaia River, supported by stored water from Lake Coleridge, Stage 2 consists of 199 kilometres of pipeline, 12 pump stations and 3 pressure-reducing stations, delivered in 2018 on time and budget, construction cost $182 million.

2018 – Turning on the water

In September 2018, 135 years after Malvern Country Council made the first approach for a large-scale irrigation scheme, construction was complete. Low-nutrient alpine water was being provided through a network of underground pipes to irrigate approximately 45,000 hectares of land - delivering environmental, economic, and social benefits to the wider community.

2019 – Groundwater recharge

By providing an alternative source of water switching off groundwater extraction and permanently converting irrigators to low-nutrient alpine water, 55 million cubic metres of groundwater have been retried from use in irrigation. It is this reduction of groundwater usage that has ensured the sustainability of water recourses.

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