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Alligator Weed Identified at Lake Whatumā

Alligator weed 2 1920

Hawke’s Bay Regional Council (HBRC) has confirmed the presence of Alligator weed at Lake Whatumā (Lake Hatuma) in Central Hawke’s Bay. 

Alligator weed is an invasive pest and recognised as a severe threat to agriculture and biodiversity.  Listed as an Exclusion Pest under the Hawkes Bay Regional Pest Management Plan 2018-2038, it is very aggressive, has an exceptionally deep root system and spreads readily from only minimal plant matter. 

Iain Maxwell, Hawke’s Bay Regional Council Integrated Catchment Management Group Manager says, “Our biosecurity team identified Alligator weed at Lake Whatumā on 12 April and their initial actions focussed on notifying properties adjacent to the lake and erecting signage to encourage biosecurity measures to limit further spread.”

Alligator weed is already a major problem in Northland and infestations have also been identified in Waikato and Manawatu.  It out competes pastures and crops, is toxic to stock, blocks waterways and drains and may affect whitebait spawning areas.

HBRC have been in touch with mana whenua, all the lake stakeholders as well as the Department of Conservation, Hawke’s Bay Fish and Game and the Whatumā Catchment group. 

The focus this week is on conducting an extensive delimiting survey to determine how widespread the weed has become.  This will include searching the entire Mangatarata Stream as well as any inlets to the lake.

Once the delimiting survey has been completed and the full extent of the outbreak is known, Maxwell says this will enable the Regional Council to finalise a control and management plan with a goal of eradicating the weed and stopping further spread. 

On completion, survey results and the management plan will be shared with all stakeholders and the community.

If you see Alligator weed please email:

For more information, please see this link.





Need more info?

Contact Communications Advisor Brendon Lane | Phone 027 320 3523

24 April 2023

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