Water in Nelson - FAQ

Frequently asked questions on water issues throughout Nelson, including drinking water supply, stormwater intakes, works on Rutherford Street and Devenish Place.

Where are things currently? 

Our focus now is on the immediate recovery. There’s a lot for our teams to do to get Nelson back on its feet, but once this has happened, we will look at how the river behaved during this extreme weather event and whether anything more can be done to protect properties from flooding and slips looking ahead. 

Water supply – do we have enough? 

The situation with Nelson’s water supply is improving. We’ve been able to increase capacity from our Roding reservoir and are no longer needing to take water from Tasman District Council. We are also carrying out repairs to protect the buried duplication pipeline on Maitai Valley Road. This means that normal winter water usage is now fine.  

However, as we are still operating at a reduced capacity and are asking residents to continue to be mindful of their water usage and try and restrict the clean-up jobs that require more water to be used outside of our peak hours (7-9am and 4-8pm). Thank you for your continued cooperation. 

Storm culverts near Nile Street  

Secondary flow from the culvert at Cleveland Terrace affected private property on Nile Street East, as it did in 1970 and 2011. There have been significant stormwater upgrades on this street. Following the 1970 flood, the intake and culvert were upgraded. In 2009, a 1.2m diameter pipe was installed downstream of the chamber on Cleveland Terrace, and in 2019 Council installed a new 1.6m diameter stormwater main on Nile Street East.  

Modern stormwater culverts are built to withstand substantial rainfall events, but the volume of water (along with gravel and debris) experienced in this event was more than any culvert could cope with.   

We are also looking into the flood gate at 231B Nile Street to see what impact it had on the area. However, high flood levels were also caused by the overtopping of the Maitai River stopbank between Hanby Park and 25 Mill Street, as well as the overland flow from Cleveland Terrace. 

Secondary stormwater flow – Devenish Place  

You may have seen a picture of the damaged road at Devenish Place on social media. A slip blocked the intake to the stormwater line, and when nearby Oldham Creek overtopped this caused more stormwater than normal to flow down the road. This eventually resulted in the road’s collapse during the weather event. 

There has been some commentary suggesting that the pipes visible in the photograph are the main stormwater pipes for this road, that is not the case. It is hard to see, but the concrete stormwater pipe, which is 0.9m in diameter, runs across the road left to right and is much bigger than the small white pipes. The smaller white pipes are for wastewater.   

It is common throughout New Zealand for secondary stormwater flow (the natural path that stormwater takes where it exceeds the capacity of the primary stormwater pipe, or where there is a blockage) to travel down roads and other natural topography. By pushing stormwater flow to these places, we reduce the amount that drains that could potentially flow through private property.   

Our roading team have filled in the road temporarily to provide access to residents in preparation for it being repaired as soon as possible. 

Why can’t you reopen Waimea Road/Rutherford Street to ease congestion? 

Work on the stormwater upgrade on Waimea Road/Rutherford Street is ongoing. There are large excavations in the road where stormwater pipes are being installed so it is not possible to pause the works. This work started before the weather event. One lane is open on Rutherford Street, but it is not possible to open the southbound lane on Waimea Road as the entirety of the road is being used for the works. 

Congestion on this road has been reduced now we have partial opening of Rocks Road, but please drive slowly and carefully through the detour, looking out for pedestrians and cyclists. If you can work from home and avoid the road altogether that would be appreciated.