Current river works

Here you can find information on our current works operations. Dates given are indicative as weather may delay work completion. 

We also provide a monthly workplan. This plan is an overview of upcoming and current river works operations by area and river. Download workplan - Kaikōura to Waitaki (PDF file, 253.38KB).

For any queries call 0800 324 636.

Targeted weed control works

Starting early February to March 2024

We will be surveying the rivers first to identify islands in the riverbed that require weed control and then spraying targeted weed species (specifically willows, gorse, alder, poplar, broom and lupins) growing on these specific islands.

Signage indicating that spraying is underway will be placed at all spray operation refilling stations and public access points on the river. Public access will be restricted during operations.

WHAT: Targeted weed control using helicopters for aerial spraying

WHERE: Please see the detailed maps below of the rivers

WHEN: Early February through to March, as weather permits

Why do we control weeds in the riverbed

Healthy waterways are central to a healthy environment. Our rivers are important places of cultural and ecological significance ki uta ki tai. Our waterways are vulnerable to harmful weed infestations, so we need to manage weeds for flood control and biodiversity protection

Our staff and contractors carry out weed control measures in the open riverbed to help flood flows pass through and enhance biodiversity values. Left unchecked, invasive weeds are a significant flood risk, occupying the channel and forcing flood water towards neighbouring communities and farmland. Weed growth can also contribute to the loss of aquatic habitats and nesting areas for native birds.

Find out more about weed control work, including the type and method of control we use.

Areas of spraying

Northern areas

Central areas

Southern areas

Fairway weed spraying in Hekeao Hinds River

Starting mid February 2024 for up to three weeks

In February we are starting a programme to remove weeds that are spreading and constricting the Hinds River fairway.  

We will be using vehicles with mounted spraying equipment for targeted spraying, commencing the week following Waitangi Day holiday week. 

Weed control clears the active part of the river channel that carries fast flowing water during floods. Clearing the active channel also allows for better habitat and improved biodiversity.

Access to the river may be limited while the works take place for health and safety reasons.

WHAT: Ground spraying for targeted weed control, to increase free flow of the river within the fairway

WHERE: The Hekeao Hinds River Downstream of the Pooles Road River crossing to 200m upstream of Long beach Road river access

WHEN: Spraying from early February

Huritini Halswell River Weed Barrage

Starting mid-February to May 2024

We have engaged contractors and are about to start physical works to replace the Huritini/Halswell Weed barrage. The proposed works include upgrading and replacing the existing temporary weed barrage across the Halswell River. The new barrage will provide a more robust solution with a longer service life and will continue to ensure we can maintain the weed cutting programme on the Halswell River into the future. 

This operation will involve:  

  • The temporary storage of materials (rock, piles, and machinery) 
  • Carting rock by truck and trailer to site along both Sportsman Avenue and along the true left bank spoil track (access from Ducks Pond Road) [February]  
  • Temporary bank stability works to create a platform to access the river [February/March]  
  • Installation of 10 piles across the river by use of excavator [March]  
  • Installation of rock lining in the riverbed [April].  

Works are being done in accordance with resource consents: CRC235345 & CRC235346. Access to the river via the Greenpark Huts boat ramp will be maintained for the duration of works.   

WHAT: Installation of a new Weed Barrage  

WHERE: Huritini Halswell River – Greenpark Huts at the end of Sportsman Ave  

WHEN: Mid-February to mid-May 2024   


Cam River/Ruataniwha tree maintenance

Late November to early-2024

From late November, we will be carrying out maintenance works on willows in the Cam River to improve the flow capacity of the river and reduce flood risk. This work will involve topping and trimming back these trees and, in some cases, their removal.   

Bank disturbance will be kept to a minimum and no native vegetation will be removed.  

Many of these trees are in poor health and pose a risk to the community, as they could fall onto banks/tracks or into the river, impeding water flow, which could lead to out of channel flooding. 

This work will be undertaken by contractors and Environment Canterbury staff. 

WHAT: Maintenance and removal of willow trees     

WHERE: Cam River/Ruataniwha, starting at Bramleys Road and working downstream towards SH1 

WHEN: Monday 27 November to Christmas, then from mid-January to late February 2024 

Targeted control of Russell lupins in Upper Waitaki

November 2023 to February 2024

We are starting targeted weed control of Russel lupins in the Upper Waitaki from mid-November 2023 through December, followed by ground-based spraying in February as weather permits.   

Surveying has identified islands in the riverbed that require weed control and we will be spraying weed species (specifically willows, gorse, alder, poplar, broom, and lupins) growing on these islands.   

This is earlier than our regionwide spraying programme as part of our commitment to reduce the amount of agrichemical we use. This is because plant uptake of chemicals is greater in November than at the start of the New Year. With higher uptake, fewer chemicals will be required.

Russell lupins have germinated by February and seeds have likely ended up in the riverbed, so early weed control will help eliminate this seed spread.  

It is unlikely for birds to nest in areas of high vegetation which are the areas being targeted however, we will be completing a drone flight to identify any nesting birds in the area prior to spraying. A flyover will also be conducted prior to spraying to check for the presence of anglers. Spraying will occur in the early morning and late afternoon to avoid bees.  

Signage indicating that spraying is underway will be placed at all refilling spray operation areas and at public access points on the river. Public access will be restricted during operations.  

WHAT: Targeted weed control using helicopters for aerial spraying followed by ground control 

WHERE: Pūkaki, Takapō, and Ōhau Rivers  

WHEN: Mid-November through to December 2023, followed by ground-based spraying in February 2024

Areas of spraying


Upper Waitaki Upstream of gorge Grays to Edwards

Upper Waitaki - Upstream of gorge Grays to Edwards

Upper Waitaki - Pukaki-River

Upper Waitaki - Pukaki river

Upper Waitaki - Ohau River

Upper Waitaki -
Ohau river

Upper Waitaki - Lake George Scott

Upper Waitaki - Lake George Scott

Upper Waitaki - Edwards to LINZ boundary

Edwards to LINZ boundary

Upper Waitaki - Delta to Greys

Upper Waitaki - Delta to Greys

Upper Waitaki - All

Upper Waitaki -

Ashley Rakahuri Karoro/Southern black-backed gull (SBBG) control

September 2023 – February 2024

We are conducting a Karoro/Southern black-backed gull (SBBG) control operation from September 2023 until February 2024 – the nesting season for SBBG – targeting eggs and nests, at the Ashley River/Rakahuri. 

The Ashley River/Rakahuri is home to a number of rare, threatened bird species that nest on the riverbed, such as black-fronted tern/tarapirohe, black-billed gull/tarāpuka, wrybill/ngutu pare and banded dotterel/tūturiwhatu.  

The aim of the control operation is to displace the SBBG population from the estuary as effectively and humanely as possible by removing eggs and nests, without compromising the safety of non-target species or the public. This is to discourage karoro from using the site for future nests, thus assisting with the recovery of threatened braided river bird species. It is hoped the SBBG will move further out of the hapua, making it more-available for the rest of the estuary’s diverse bird population. 

We are also working with Ngāi Tūāhuriri on egg removal for mahinga kai/mahika kai, which relates to the traditional value of food resources and their ecosystems, as well as the practices involved in producing, procuring and protecting these resources.  

WHAT: Karoro/Southern black backed gull control    

WHERE: Ashley Rakahuri River  

WHEN: September 2023 – February 2024  

2021 flood recovery works

2021 - 2024

In winter 2021, constant, heavy rainfall led to flooding throughout Waitaha Canterbury, particularly between the Waimakariri District through to the Mackenzie Country. The extreme weather event caused damage to homes, land and flood protection infrastructure. 

Flood recovery works map 

Immediately following the mid-2021 floods, we assessed Environment Canterbury-owned flood protection and erosion control infrastructure across Waitaha.

The remaining infrastructure repair works have been given a high, medium or low priority to assist with work scheduling. We have an interactive map where you can find more information about our flood repair works, including finished works. 

The Climate Resilience Programme 

As part of the Central Government COVID-19 recovery programme, we have an additional $24.2m investment in river enhancement occurring across Waitaha, as part of the Resilient River Communities Programme. There are six projects being delivered as part of this programme.  

This collaborative funding investment, being made over three years, is enabling us to undertake significant upgrade work, construct new infrastructure and improve existing natural infrastructure, that would have otherwise taken many years to fund through rates alone.  

As the flood remediation works are completed, communities across Waitaha will benefit from increased flood resilience and protection, and enhanced biodiversity in our river corridors.  

Updates on the six projects that make up our Climate Resilience Programme can be found on the project webpages