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Pest plant control over water

Image - alligator weedOperations under Resource Consent 124871

Every year Waikato Regional Council carries out targeted spray operations to control invasive pest plants growing in our rivers, lakes and wetlands.

This work is important to protect the environment – and in particular agricultural production – from the impacts of these pest plants, as well as to improve biodiversity.

Council holds a resource consent for the application of agrichemicals to air where they may enter water and the coastal marine area within the Waikato region. 

This consent allows the use of specific herbicides for controlling pest plants that cannot generally be controlled with glyphosate.

Resource consent details

Consent no: 124871

Consent description: Aerial application of agrichemichals to air where it may enter water and the coastal marine area within the Waikato region. 

What pest plants are we controlling?

The pest plants to be controlled in 2019/20 include, but are not limited to the list below. These plants all grow in and around aquatic or marine areas, which means the herbicides we use may enter water.


The resource consent permits the use of the following herbicides.

Spraying will be by knapsack, hand spray equipment (e.g. gun and hose/mist blower) or helicopter using low drift nozzles.

Active ingredient Example brand name
Haloxyfop-R-methyl Agpro Haloxyfop 100, Gallant™ Ultra
Imazapyr isopropylamnine Unimaz™ 250 SL
metsulfuron-methyl Agpro Meturon®, Associate® 600WDG, Escort®,
Triclopyr trimethylamine salt Garlon™ 360
Polyether modified polysiloxane Agpro Organosilicone, Pulse penetrant

Note: Glyphosate use is a permitted activity in the Waikato Regional Plan.

Where are we spraying?

Image - using the mapClick on the link below to see a map of operational areas for 2019/20. Operational areas are shown on the map with purple shading.  


Use the Search bar in the top left-hand corner to search for your address and see where spraying is happening in relation to your property.

When are we spraying?

Application may occur at any time during daylight hours, providing weather and tide conditions are suitable. 

As these pest plants are difficult to control, two to three follow-up applications may occur over the next 12 months. It is unlikely that spraying will occur during duck shooting season. There will be no spraying on public holidays.

See the list of scheduled spraying operations at the bottom of this page.

Image - using the maps - image 2Register for notifications

You can be notified by email or text message of specific times when spraying is happening near your property.

Use the map to identify the operational area you want to be notified for. Click on the area and then click "Sign up for notifications". This will direct you to an online form to register for notification.


Scheduled herbicide control operations

Below is a list of scheduled spraying operations. This list will be updated regularly so please check this page for updates.  Click here for past spraying operations.

Date Location Control type Herbicide Map number/s Target pest plants
17 Oct - 7 Nov 2019 Komakorau Stream Knapsack Metsulfuron 80 Alligator weed
14 Oct - 4 Nov 2019 Tuhikaramea Stream Knapsack, gun & hose, mistblower Metsulfuron, Glyphosate 77 Yellow flag iris
9 Oct - 30 Oct 2019 Lake Whangape and Whangamarino River Helicopter Metsulfuron  6, 8 Alligator weed
9 Oct - 30 Oct 2019 Whangape Stream Mist blower Metsulfuron 6 Alligator weed
3 Oct - 24 October 2019 Waikato River from Mercer Bridge to Ngaruawahia Mist blower Metsulfuron 5A, 5B, 9, 10A, 10B, 11A Alligator weed
3 Oct - 24 October 2019 Whangamarino River and Wetland Mist blower Metsulfuron 8 Alligator weed
19 Sept - 3 Oct 2019 Waimaori Road - Toreparu Stream Knapsack Metsulfuron 55 Alligator weed
19 Sept - 3 Oct 2019 Ruapuke Stream Mouth Knapsack Metsulfuron 36 Alligator weed