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CPWL Water
Stewardship

CPWL Compliance and Oversight Water Stewardship

CPWL provides environmental monitoring data to the Trust, which is independently reviewed by the Ground and Surface Water Expert Review Panel (GSWERP), approved by Environmental Canterbury. The Trust consolidates this information into its annual Sustainability Report, which is then provided to the settlors – Selwyn District Council and Christchurch City Council.

Sustainability report

Surface and Groundwater Monitoring

Monitoring both surface and groundwater is essential to understanding the environmental effects of the CPWL scheme. Since 2014, nearly 3,500 water samples have been collected from 60 sites across the region, helping to track key indicators like nitrate levels and support targeted action where needed.

Long-term monitoring shows that groundwater nitrate trends are consistent with regional patterns observed by Environment Canterbury. Early observations also suggest potential improvements in groundwater quality beneath the oldest parts of the scheme, though further data is needed to confirm these trends. Additional data is being collected across the scheme to strengthen confidence in long-term trends and guide future planning.

By gathering robust environmental data and acting on it, CPWL transparently meets its compliance obligations and contributes to the settlor’s objective of continuous improvement in regional water.

CPWL Compliance and Oversight Water Stewardship

The reliability of alpine-sourced surface water supplied through CPWL has significantly reduced shareholder reliance on groundwater. This shift supports aquifer recharge and enhances flows in lowland streams that feed into Lake Ellesmere, Te Waihora.

Before the scheme was operational, groundwater abstraction made up more than 95% of allocated water in the Selwyn Waihora catchment. CPWL now provides a sustainable alternative, helping address historical overallocation and align with the regional target of an 80% reduction in groundwater use across the Selwyn-Waimakariri and Rakaia-Selwyn zones.

Since the scheme began, groundwater use by CPWL shareholders has dropped by 68% – from 99 million cubic metres in 2014/15 to 32 million in 2022/23. In addition, 18.5 million cubic metres of annual groundwater allocation has been permanently surrendered. These results demonstrate measurable progress toward reducing pressure on aquifers and restoring the natural balance needed for ecological and cultural flows.

Recharging Aquifers,
restoring flows

Near River Recharge

The Selwyn, Waikirikiri Near River Recharge project is a mult-million-dollar initiative that uses alpine sourced water and infrastructure from the CPWL scheme to recharge groundwater near the Selwyn River during dry periods. This helps sustain flows in the in the Selwyn, Waikirikiri and Hororate Rivers and supports ecological health through naturally filtered and high-quality water.

The project was recommended by the Selwyn Waihora Water Zone Committee and included in the Zone Implementation Programme Addendum in 2013. It was funded by Environment Canterbury and the Ministry for the Environment’s Freshwater Improvement Fund, with in kind support from CPWL.

Greendale School students have adopted the recharge site as a living classroom, learning about biodiversity, freshwater systems, and the practice of kaitiakitanga through hands-on monitoring and ecological restoration.

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