Current river works
Here you can find information on our current river maintenance works we are undertaking across the region through targeted rates from river rating districts.
This includes operational tasks such as:
- weed control
- tree maintenance or removal
- infrastructure inspections.
Monthly river works plan: We also provide a monthly work plan that provides an overview of upcoming and current river works operations by area and river. Download the work plan—Kaikōura to Waitaki February (PDF file, 571.71KB)
Annual work plans: Find out what flood protection and drainage scheme maintenance activities are planned in your rating district from July 2025 to June 2026. Download work plans: southern region (PDF file, 2.7MB), northern region (PDF file, 1.86MB), central region (PDF file, 3.7MB)
Need more information or help? Contact our customer advisory team via our online form or call 0800 324 636.
Note: Dates given are indicative, as weather may delay work completion.
Ruataniwha/Cam River - Cox Rd and SH1 native planting
What: We will undertake riparian native planting of approximately 900 plants along the banks of the Ruataniwha/Cam River during April and May. Site preparation will involve grass scraping, the use of organic herbicides, or grass grubbing. Preparation is expected to begin in early April, with planting occurring progressively from early April through May. The planting at SH1 will focus on infilling gaps within the existing WDC asset.
Where: True left bank of Ruataniwha/Cam at Cox Road. True right bank of Ruataniwha/Cam at SH1, downstream of the SH1 bridge.
When: April and May 2026.
View areas of planting areas in green
Ashley River culvert inspections
What: We're going to be carrying out inspections of culverts using a CCTV camera van operating along the stopbank, in the areas marked red on the map. The inspections help us check the condition of culverts that are part of the flood protection system and plan future maintenance. A vehicle and crew will be present while inspections take place.
Where: Along sections of the Ashley stopbank, including areas where public walking and cycling tracks are located. See map.
When: Starting Monday 16 March, with work expected to take approximately one week, weather permitting.
🚧While the work is underway, there may be minor disruption for track users. Please take care around the vehicle and crew.
View area of Ashley River culvert inspections
Ōtukaikino Creek – Willow Control Works
What: Willow control works will be carried out at three locations along Ōtukaikino Creek. The work includes mechanical and hand felling, as well as drill‑and‑fill treatment, targeting crack willow, grey willow and alder. These trees are being removed to improve river flow capacity during high flows and flood events. In several locations, trees are encroaching into the channel and creating blockages that increase flood risk.
Where
- The Groynes to Dog Park area (both banks): Trees will be removed using mechanical and manual felling. In‑channel blockages will be cleared by working from the riverbanks. Appropriate measures will be put in place to manage sediment and reduce environmental risks during the works.
- Upstream of Dickeys Road Bridge (both banks): Follow‑up drill‑and‑fill treatment will be undertaken in areas that have been previously cleared.
- Waimakariri Reserve (true right berm): Trees will be removed using a combination of mechanical and hand felling. This work will improve flood flow capacity and reduce the risk of debris and obstructions forming during flood events. Clearance at this site will be staged, taking place over autumn 2026 and the following two summers. Replanting with appropriate native vegetation will be carried out at the mechanical felling sites once removal works are complete. Best‑practice river management and environmental controls will be applied at all sites.
When: Clearance at this site will be staged, taking place over autumn 2026 and the following two summers
🚧 Please expect temporary track closures on the work areas on the maps - signage will be in place when closed.
Figure 1: The Groynes to dog park target area
Figure 2: Dickeys Road bridge target area
Figure 3: Waimakariri Reserve target area
Ōrāri stopbank - Notice of operations
What: We are refurbishing (rebuilding) existing stopbanks along the Ōrāri River River to bring them up to meet design heights. This will help them better protect surrounding land from flooding.
Where: Along the Ōrāri River, on the true left bank (the left-hand side when facing downstream), between the State Highway 1 bridge and the KiwiRail bridge.
When: March 2026
Why we’re doing this work: The current stopbank crest is lower than it should be and requires rebuilding to meet our bank batter (sloping sides of the stopbank) and crest design criteria. This work will improve flood resilience within the Ōrāri scheme.
Area of work in red
Ashburton Hakatere River north branch gravel extraction
WHAT: We are extracting gravel from the riverbed for to help with flood protection.
WHERE: The north branch of the Ashburton Hakatere River upstream from Walkhams Road (see map).
WHEN: Early March – end of April 2026.
WHY: This work is taking place on the north branch of the Ashburton Haketere River, upstream of Walkhams Road. It includes removing gravel from the riverbed, where severe aggradation (build-up) has decreased the flood capacity within this narrow reach of the river. The gravel will be stockpiled and available for other construction projects of significance to the local community.
The area of work is in red
Forestry Harvesting at ‘Grassy Banks’ site on Ōpihi River
WHAT: We are harvesting of around 27 hectares of poplar forest on the southern bank of the Ōpihi River. The area is being harvested for timber and will be replanted in another forestry crop, the species is to be confirmed.
Parts of the river, including access tracks and roads, will be closed to the public while harvesting takes place.
WHERE: The poplar forest is on the Southern side of the Ōpihi River at the top of Seadown Road, between the SH1 bridge and Waipopo Road.
WHEN: The harvesting crew are aiming to start on the week of 2 March 2026. The operation is expected to take 10 weeks.
WHY: These poplars were planted for flood protection. As they have matured, harvesting them is now the best way to manage the trees and make use of their value. The income generated will be reinvested into flood protection work across the Ōpihi catchment.
The area of work is in blue
Ashley Rakahuri River tree maintenance
WHAT: Removal and trimming of overgrown and fallen trees within the berm
WHERE: North bank of the Ashley Rakahuri River upstream of the SH1 bridge
WHEN: Early March to end of April 2026
This work is located on the north bank of the Rakahuri River upstream of the SH1 bridge and includes removal and trimming of overgrown and fallen trees within the river’s berm.
Removing and trimming back overgrown trees allows for increased flood resilience as it allows flood flows to move through unobstructed and reduces debris loads during flood events, which can cause erosion and damage to bridges.
The area of work is in red
Hinds River stopbank improvements
WHAT: Repairing stopbank along the Hinds River
WHERE: Two locations along the Hinds River stopbank
WHEN: Late February through April 2026, depending on weather and river conditions
Essential stopbank repair works are planned at two priority sites along the Hinds River as part of the Regional Infrastructure Funding (RIF) Flood Resilience Tranche 1 programme. This project is co‑funded by central government via MBIE‑Kānoa – Regional Economic Development & Investment Unit.
The project includes several improvements to strengthen the stopbank and improve long‑term flood protection:
- Removing and fully rebuilding approximately 435 metres of stopbank at Site A, where buried tree stumps are affecting stability.
- Raising approximately 300 metres of low stopbank at Site B.
- Completing several smaller repairs to address individual defects.
- Removing and managing on‑site waste materials as required.
These repairs will improve the resilience of flood protection infrastructure within the Hinds catchment. Addressing known defects now will help ensure the stopbank continues to perform as intended during flood events. The rebuild at Site A is particularly important due to the presence of buried tree stumps, which compromise long‑term stability.
The different work areas
Courtenay Stream floodgates construction
WHAT: Replacing the Courtenay Stream floodgates in Kaiapoi
WHERE: At the confluence of Courtenay Stream and the Kaiapoi River
WHEN: Work begins the week of 2 February 2026 and is expected to be completed by October 2026
The current floodgates were built in the 1940s and are now due for renewal.
This upgrade is co‑funded through the Government’s Regional Infrastructure Fund (RIF), administered by Kānoa – the Regional Economic Development & Investment Unit. It also forms part of our 30‑Year Infrastructure Strategy (30YIS), which accelerates essential flood‑protection upgrades across the region.
The project includes removing the old structure and building new floodgates in the same location, starting with environmental controls, site setup, fencing, and public access changes. The upgraded structure will improve flood resilience, make maintenance safer for staff, and provide much better fish passage.
To keep the stopbank track open during construction, a temporary bridge will be installed over Courtenay Stream next to the work area.
The different work areas
Tree control at Ruataniwha Cam River
WHAT: Follow up tree control via targeted methods (drill and fill, cut and paste, and targeted spraying). Targets are willow seedlings and juveniles, willow stumps, and topped willows requiring follow-up control. Hawthorn and other wilding exotic trees will also be controlled.
WHERE: True right bank (300 meters) of Ruataniwha Cam River, downstream of SH1 bridge.
WHEN: February to March 2026
Location of tree control
Ruataniwha Cam River stopbank remediation works
WHAT: Stopbank remediation works
WHERE: Ruataniwha Cam River at SH1
WHEN: Januray to March 2026
We’re remediating a stopbank on the true-right bank of the Ruataniwha River to bring it up to design height and profile.
This site is highly visible from SH1 and works will be completed by a mix of Environment Canterbury staff and contractors.
This work is co-funded through the Regional Infrastructure Fund (RIF) Flood Resilience Programme and is a part of our 30 Year Infrastructure Strategy.
On the true right bank of the Ruataniwha River, downstream of the SH1 bridge. Total length of bank being upgraded: approx. 300m.
Works scheduled to start week on 19 January 2026 and anticipated to be completed in approximately 8 weeks.
Orange line indicates work
Weed cutting and removal from Huritini Halswell River
WHAT: Weed cutting and removal from Huritini Halswell River
WHERE: Huritini Halswell River (see map)
WHEN: From Monday 12 January to Thursday 30 April 2026
We are carrying out our annual weed cutting work, including the raising of the weed barrier in Huritini Halswell River, so we can cut and collect weeds from the waterway.
This is an essential part of river maintenance to help control excessive macrophyte growth which raises water levels and contributes to flooding and drainage issues in the catchment.
We’ll be using a weed cutting boat and the cut weed will float downstream until it is captured on the weed barrage (a type of net) and removed via a dragline.
The barrier is in the Huritini Halswell River near Motukarara and Greenpark Huts and cutting in the river will occur from the mouth of Te Waihora upstream.
The work will take place in the red area
Regional targeted weed control - aerial
WHAT: Weed control using helicopters for aerial weed spraying
WHEN: Mid-November to December 2025 for South Canterbury, early February to late March 2026 regionwide, as weather permits
WHERE: Canterbury Rivers: fairways, access tracks, stopbanks and around the rivers and drains listed below.
North Canterbury
Kowhai River aerial work
Hurunui River aerial work
Pahau River aerial work
Waiau River aerial work
Conway River aerial work
Waimakariri River aerial work (Map 1 of 5)
Waimakariri River aerial work (Map 2 of 5)
Waimakariri River aerial work (Map 3 of 5)
Waimakariri River aerial work (Map 4 of 5)
Waimakariri River aerial work (Map 5 of 5)
Central
Hakatere/Ashburton River, including Taylors Stream aerial work
Rakaia River aerial work
Waikirikiri/Selwyn River aerial work
Huritini/Halswell River aerial work
We will be surveying the specified rivers to identify islands in the riverbed that contain weed species, before undertaking targeted spraying from a helicopter. 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. An aerial flyover will be conducted prior to spraying to identify any river users.
Why do we control weeds in the riverbed?
Healthy waterways are crucial 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, and we need to manage weeds for flood control and biodiversity protection. Left unchecked, invasive weeds are a significant flood risk, occupying the channel and forcing flood waters towards neighbouring communities and farmland. Weed growth can also contribute to the loss of aquatic habitats and nesting areas for native birds.
What chemicals do we use for targeted weed control?
We use herbicides (glyphosate and triclopyr) under strict controls to manage weed growth in riverbeds and berms under the terms of the resource consents CRC222040, CRC222041 and CRC222043.
Glyphosate is widely used in New Zealand and other countries as a general-purpose herbicide, it is regulated in New Zealand by the NZ Environmental Protection Authority (EPA) and there are laws around its use. Products containing glyphosate are considered safe when the safety instructions on the product labels are followed.
- Read EPA’s statement about glyphosate and information about how glyphosate is regulated in New Zealand
Regional targeted weed control - ground-based
WHAT: Ground-based weed control spraying across Canterbury
WHEN: September 2025 to March 2026
WHERE: Canterbury Rivers: fairways, access tracks, stopbanks and around the rivers and drains listed below.
Northern rivers
- Kaikōura Rivers (Kowhai, Lukes Creek, Middle Creek, Harnetts Creek, Floodgate Creek, Waimangarara, Lyell Creek)
- Kaikōura Drains
- Waiau Uwha River
- Chatterton/Rodgerson River
- Hurunui River
- Ashley river
Waimakariri-Eyre-Cust rivers
- Waimakariri River
- Eyre River
- Cust River
- Cam River
- Kaiapoi River
Central rivers
- Ashburton Hinds Drainage Scheme
- Halswell Drainage Scheme
- Ashburton River (including the main stem, North Branch, South Branch, Taylors Stream, Bowyers Stream, Pudding Hill Stream)
- Hinds River
- Halswell River
- Okana River
- Okuti River
- Opuahou Stream
- Hukahuka Turoa Stream
- Rakaia River
- Selwyn River
- Hororata River
- Hawkins River
- Waianiwaniwa River
Southern rivers
- Hook Drain
- Waihao River
- Waitaki River
- Upper Waitaki Rivers (Takapo, Pukaki, Ohau)
- Taumatakahu
- Te Aitarakih
- Seadown Drains
- Clandeboye Drains
- Rangitata River
- Orari River
- Waihī River
- Temuka River
- Ōpihi River
- Tengawai River
- Opuha rivers
- Pareora River
- Makikihi River
- Otaio River
Why do we control weeds in rivers
Our rivers are vulnerable to invasive weed infestations, and we need to manage harmful weeds for flood control and biodiversity protection. Left unchecked, invasive weeds contribute to significant flood risk by occupying the channel, which can obstruct natural water flow and redirect floodwaters onto riverbanks or stopbanks. This can cause erosion and put critical flood protection infrastructure at risk. Weed growth can also contribute to the loss of aquatic habitats, nesting areas for native birds and reduce native plant populations.
Our qualified staff and contractors carry out weed control measures in the open riverbeds within our drainage channels and on our berms and stopbanks, to help protect our communities from flooding and enhance biodiversity values.
What chemicals do we use for targeted weed control?
Environment Canterbury uses glyphosate (a general broadleaf weed killer), triclopyr (brush weed killer), and surfactants under strict controls to control weed growth in riverbeds and berms under the terms of our resource consents CRC222040, CRC222041 and CRC222043.
Glyphosate is widely used in New Zealand and other countries as a general-purpose herbicide, it is regulated in New Zealand by the NZ Environmental Protection Authority (EPA) and there are laws around its use. Products containing glyphosate are considered safe when the safety instructions on the product labels are followed.
- Read EPA’s statement about glyphosate and information about how glyphosate is regulated in New Zealand
- Learn more about why and how we control weeds in rivers