Clutha Upper Waitaki Lines Project FAQs

What work is needed to finish the Clutha to Upper Waitaki Lines project (CUWLP)?

The CUWLP comprises five pieces of work to increase capacity to and from the lower South Island. Two of these, to better facilitate southerly flows (ie into Southland), have already been completed. Three tranches of work remain to be completed to better facilitate northerly flows (into the Waitaki Valley):

  • Duplexing the Roxburgh–Livingstone line section of the Islington-Roxburgh line with a duplex conductor
  • Thermally upgrading the Cromwell–Twizel section of the Roxburgh­–Twizel line
  • Duplexing the Aviemore–Benmore line with a duplex  conductor

At this stage we are planning for a special protection scheme to be enabled on the Aviemore–Benmore line and not undertake the duplexing of this line at this time.  We expect that scheme to be enabled around winter 2021.

When did Transpower decide to proceed with the remaining parts of this Project?    

In June 2020 we announced our decision to continue with the Roxburgh–Livingstone duplexing and the Cromwell–Twizel thermal upgrade.  Enabling works for both projects had earlier commenced following a funding agreement with both Meridian and Contact Energy signed in December 2019.   The cost of the remaining work is estimated to be $100m.

What has changed since New Zealand’s Aluminium Smelter’s (NZAS) recent announcement?  

Following NZAS’s recent announcement, we have undertaken an assessment of the acceleration of the remaining sections of work for the project.  We are now targeting an estimated completion date of May 2022 - a year earlier than had originally been planned. It is possible that further acceleration initiatives during project delivery could lead to a slightly earlier date, but this will only be known as the project progresses on the ground.

What will accelerating the project mean in practical terms?

It will mean putting more work crews (up to about 130 people employed by our service providers and Transpower directly) on the project, undertaking more project works concurrently and accelerating procurement, consenting and access approval processes.

What are 'duplexing' and 'thermal upgrade'?

Duplexing involves the stringing of a second conductor (wire) where only one existed previously, while a thermal upgrade increases an existing conductor’s capacity to carry more electricity, by operating at a higher temperature.

Will this impact on Transpower's other programmes of work?

Accelerating this project will require us to reschedule other work in our programme.  We are working through the detail of this but believe we can reschedule other work without creating undue risk from an asset health perspective.

Does Transpower have property rights and environmental consents to complete CUWLP?

Based on our experience so far, we believe most of the remaining CUWLP works will not require the negotiation of easements or other formal land access rights.  We do however need to work with landowners to agree timing of the work to be as least disruptive as possible to their operations. 

The consenting process is well underway to enable the works to proceed; however, many activities are covered by the National Environmental Standard for Electricity Transmission Activities (NESETA), where consents are not required. At some locations, Heritage Approvals under the Heritage New Zealand Pouhere Taonga Act 2014, may also be required.

If the Tiwai aluminium smelter closes prior to this project being completed would the transmission network be able to move electricity north?

The CUWLP increases capacity into the Waitaki Valley for all generation south of it. If Tiwai closes prior to completion of this project, then we may not be able to fully dispatch generation from southern hydro lakes on the power system.

How much more capacity will this project provide?

When completed, the project will almost double the existing capacity (from around 600 MW to around 1000 MW) at n-1 conditions (ie allowing for the loss of any one of the connecting circuits).  This compares to around 600 MW that is used by the Tiwai Smelter currently.

What impact does this project have on the potential pumped storage project for Lake Onslow?

The CUWLP project will bring capacity through to the upper Waitaki Valley over our existing lines. It is now more important because of the decision by NZAS to leave Tiwai. These lines would also be used to transport any electricity generated at Lake Onslow. However, further project work would be required.

What does approval of Transpower’s project under the fast-tracked consenting process, mean?

Transpower welcomes the Government’s approval of its application for the Clutha Upper Waitaki Lines Project (CUWLP) under the COVID-19 Recovery fast track consenting process. This means that if needed we can rely on getting environmental approvals to do the work faster, and with more certainty, than the normal regulatory process would allow.


We made the application to support our objective of completing the project by May 2022 which will expedite the delivery of renewable electricity northward. Because this commissioning date is a year earlier than we had initially planned (June 2023), the fast track provisions will provide us with valuable options and will assist in the event normal consenting timeframes become problematic.