Environmental Initiatives

CPWL works closely with our shareholders, stakeholders and regulators to promote and deliver initiatives that enhance environmental outcomes and reduce environmental impacts of the scheme.

Environmental Management Fund

CPWL has established an Environmental Management Fund (EMF) for the enhancement of biodiversity across the catchment. The fully operational Scheme generates approximately $115,000 annually for allocation by the EMF. Applications for funding are considered by a Committee appointed by CPWL. Applications are considered for environmental projects within the Scheme area, or for biodiversity enhancement projects in the Selwyn / Te Waihora.

The following projects will be considered by the EMF:

  1. Minimising nutrient losses to lowland streams and Te Waihora/Lake Ellesmere
  2. Excluding stock from wetlands, riparian margins and beds of rivers and streams
  3. Physical protection or enhancement of indigenous vegetation planting along riparian margins
  4. Indigenous wetland enhancement of indigenous wetland creation, including the development of indigenous wetlands along intermittent streams
  5. Permanent protection of wetland area that may contain mudfish

Funds have been provided for the planting of native species, the development of wetlands, and for research.

Efficient Water Use

CPWL shareholders are required to apply the use of good management practices and CPWL assists with this through the following initiatives:

  1. The shareholders have free access to CPWL's potential evapotranspiration (ET) website that indicates what the last ten days ET has been and what the next three days are expected to be. Shareholders can then order water according to the ET, the main driver of water loss.
  2. There are only 15 hours between the time shareholders can last order water for the next day and the water being available at the farm gate. Other irrigation schemes must order water days in advance. This enables CPWL shareholders to look at the weather forecast, soil moisture and ET and make an informed decision on whether they require water or not.
  3. Shareholders are not required to use the allocated water. In some irrigation schemes if you have ordered water then you are obligated to use it. This is not the case with CPWL. The CPWL intake gate is driven by actual scheme demand (limited by our consented take for the day). Any unused water will stay in the river.
  4. CPWL Shareholders are encouraged to place daily water orders and not to place orders a week in advance.

Aquifer Recharge

The CPWL scheme is part of the Selwyn Waihora Catchment. The Selwyn Waihora Catchment is considered "Overallocated" by Environment Canterbury (ECan). CPWL Shareholders hold groundwater consents for the abstraction of over 200 million m3.of groundwater per annum.

This volume of water exceeds available groundwater quantities, and continued abstraction will deplete the groundwater resource, reduce flows in lowland streams and hill-fed rivers and adversely affect ecological and cultural values.

Prior to the CPWL scheme delivering water to its Shareholders, approximately 100 million m3 was abstracted per annum. With CPWL now fully operational this annual abstraction has reduced to 32 million m3 as groundwater users switch to the CPWL supplied surface water.

This represents a 66% reduction in the abstraction of groundwater since the commencement of CPWL water delivery.

Te Waihora Environmental Management Fund

In addition to the CPWL EMF, funds are made available to Te Rūnanga o Ngāi Tahu for environmental initiatives associated with the restoration of health / mauri of the environment in the vicinity of Te Waihora / Lake Ellesmere.

Te Waihora / Lake Ellesmere Lake Opening

Funding is also provided for the periodic opening of Te Waihora / Lake Ellesmere to the sea to permit the flushing of water from the Lake to the sea.

More detail on the Te Waihora / Lake Ellesmere opening process can be found on the Environment Canterbury website.

Potential Evapotranspiration System

CPWL and Aqualinc have developed a website that permits shareholders to access the daily reference evapotranspiration (ET) for the scheme area. Shareholders can view the ET for the last ten days and the forecast for the next three days.

Potential Evapotranspiration is one of the key pieces of information used to make an informed decision on whether to irrigate the next day.

Selwyn Waihora DairyNZ Initiative

"Meeting a Sustainable Future Selwyn and Hinds"

DairyNZ is working one-on-one with a group of farmers and their advisors to support and explore the options for reducing their farm environmental footprint, while maintaining profitability and considering the strategic objectives of their business. This includes achieving nitrogen reductions and reducing Green House Gas emissions. The objective of the programme is to:

  • Understand options that are available to farmers to reduce their environmental footprint
  • Understand the implications of the options on the overall performance of their production systems, value of the farm and future of the farm
  • Understand what drives a farm's environmental footprint
  • Develop experience in implementing solutions
  • Demonstrate options to other farmers as they are being implemented - not just research
  • Enhance farmers showing confidence in the options available to them
  • Facilitate farmers achieving clarity on the most profitable options to reduce their environmental footprint in different conditions and farm systems
  • Define further needs for research, extension, communication and development of decision support or management tools
  • Promote learning from others
  • Inspire high performance and low footprint farms

If you are a farmer in the Selwyn Waihora area and are interested in becoming one of the supported farms or being engaged with a range of extension activities, please contact the CPWL Environmental Team for more information.

Targeted Stream Augmentation

The Selwyn Near River Recharge project includes the construction of an off-take on the Central Plains Water scheme that supplies up to 3.5m3/s of Rakaia River Water into a leaky basin beside the upper Selwyn River / Waikirikiri during dry periods.

River water discharged percolates through the groundwater system beneath recharging the aquifer, feeding springs that are the source of streams where mudfish live, and supporting flows in the interconnected Hororata, Irwell / Waiwhio and lower Selwyn / Waikirikiri rivers. It is not expected to increase the length of time the Selwyn River / Waikirikiri flows under the SH1 bridge.

Water is only discharged when forecasting indicates that the area is going into a dry period, with water discharged to keep the flows downstream the same as they would be in an average year. If it is predicted to be an average or wet year, then water is not discharged. This means in some years the system will not be used at all. The aim of the project is to:

  • Increase groundwater recharge during dry periods without increasing flooding (ground or surface water) risk.
  • Avoid direct mixing of Rakaia (source water) and Selwyn River water.
  • Minimise future drought effects on aquatic ecosystems in the Selwyn/Hororata/Irwell system.
  • Provide new Mahinga Kai opportunities at the recharge site.
  • An additional benefit is that this location has also been developed for enhanced lizard habitat and the re-establishment of native dryland species in clearings.

The basin is located on the upper Selwyn River in the middle of a pine plantation. The system only operates when the nearby Selwyn River / Waikirikiri is not flowing naturally and does not mix at the surface with natural river water. It primarily operates during winter to compensate for dry winters that result in low river flows the following summer. Monitoring of this project completed in May 2020 will be carried out to understand the impact of the Recharge project.

Other Initiatives

CPWL has completed planting at the Sheffield intake, planting 2,100 trees at the Sheffield Pond, and riparian plantings at the Hororata River Crossing.

Further initiatives include:

  • Donations to the Darfield High School Social Studies Plant Out Day.
  • Establishing, maintaining, and monitoring the Stage 1 and Stage 2 lizard habitat area.
  • Applying to the Billion Tree fund for our shareholders.
  • Providing a local country school with high visibility vests to ensure the children’s safety.
  • Working with Environment Canterbury (Regional Council) to develop an aquifer recharge project.