Taupō Stream Catchment Stormwater Improvements

This project is on hold because of budget constraints. For more information please see the Porirua City Council Long Term Plan consultation document here - refer page 23

This is a joint update from Porirua City Council and Wellington Water.  

As you are aware from our previous updates, Porirua City Council has been considering recommendations from Wellington Water on stormwater works to reduce flood risk the Taupō Stream/James St catchments. 

Wellington Water presented an update on the Stormwater Improvements projects across the Plimmerton area to Councillors in April. This included an update on the Taupō Stream/James St catchment study and resulting scope and estimates. Following the workshop a recommendation paper was prepared for consideration by Council. 

You can find more information about Wellington Water’s recommendations on the Council website:  

• View the Plimmerton Stormwater Improvement Update from Wellington Water which appeared at a Workshop of Council on 27 April 2023. 
• Read the DRAFT Technical report providing advice to Porirua City Council following the above workshop (27 April 2023), noting this has not yet been considered by Councillors. 

The Council deferred consideration of these recommendations while it worked through the Annual Plan process, which has involved looking at all expenditure in the light of affordability for ratepayers across Porirua.  Council has not included any extra budget for Taupō Stream/James St in the Annual Plan, deferring this issue for further consideration. 

Longer-term funding decisions are complicated by the Affordable Water Reforms process, as there is not yet clarity about the timelines for establishing the new water entity in this region, entity “G”. 

What this means for Plimmerton residents is that Wellington Water will continue works within the existing approved budgets, but unfortunately it will take some time to get clarity on additional longer-term funding for the full scope of works recommended. 

The $17.9 million already committed to this work includes $1 million for debris catch nets in the reserve. Work on the debris catch nets is underway. 

Taupō Stream/James St recommendation 

The results of Wellington Water’s investigation in this catchment are that it would cost an estimated $40-$63m to resolve flooding of 20-25 floors + SH59 road in a 30 year rainfall event. 

Wellington Water has identified a three stage approach: 

• Stage 1: East. An initial stage of work is recommended (circa $10m - $16m) to reduce overland flow from Camborne around James St + Greys Rd buildings by upsizing the existing Greys Rd pipes and James St intakes/outlets. 
• Stage 2: West. The second stage (circa $14m - $22m) is to ‘open up’ the choke points in the Taupo stream (primarily two vehicle bridges and the overgrown stream banks) so it is ready for the increased flow from the northeast. 
• Stage 3: North. The third stage (circa $14m - $22m) is to allow increased flow from the northeast to the Taupo Stream by constructing additional box culverts under SH59 and Ulric St and to attenuate the northwest flow from the Taupo Swamp by constructing a retention bund at the south end of the Plimmerton Domain fields. 

Wellington Water recommended progressing with design and consenting and Stage 1 works. 

Next steps 

The next step is to review what can be achieved within the existing budget, while continuing to work on proposals for longer-term funding. 

We recognise that this is not what the community wants to hear and apologise for the lack of certainty about the long-term future. Wellington Water and Porirua City Council will continue to work together to make progress where we can. 

Please contact Olivia Dovey at Porirua City Council on Olivia.dovey@poriruacity.govt.nz if you have any questions. 

Ngā mihi 

Olivia Dovey (Chief Advisor to GM Infrastructure, Porirua City Council)  

Lyndie McMillan (Wellington Water Project Director, Karehana)  

Terry Sage (Wellington Water Project Director, Taupō Stream/James St) 

Find out more about progress on the project with Wellington Water's  March 2022 update  to the community on reducing flood risk in James Street/Taupō Stream catchment.

You can read and download the update here

Read the November 2021 project overview here.