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Rotoiti Weed Spraying Update

18 November 2021

24 hour stand-down on swimming, fishing and taking water for irrigation or domestic supply is recommended

Spraying was successfully completed on Thursday 18th November at the following sites:

* Te Waiiti Point

* Gisborne Point

* Te Ruato Bay

* Hauparu Bay

* Ōkahutoroa Bay/Cherry Bay

A 24 hour stand-down on swimming, fishing and taking water for irrigation or domestic supply is recommended.


Lake weed is a problem in shallower water around the lake. Weed like Hornwart enjoys the cleaner water due to the wall in Okere channel that directs Rotorua water into the Kaituna river.

LRCA has regular discussions with LINZ (which has responsibility under Settlement Act), Boffa Miskell (manages the programme), and BoPRC (Biodiversity responsibilities), particularly to highlight the problem areas brought to LRCA attention by members, and to query when some areas are not sprayed.

Below is the email received this week confirming the spring lakeweed spraying plan, which is the largest area to be sprayed.

You can open the Rotoiti map here and zoom in on your bay. In each location with historical weed, there is a red circled zone. The yellow shaded areas identify the areas to be sprayed this time.

You will see there are some areas with no yellow shading, meaning no spray this time, and other areas where only part of the red circle are being sprayed.

We have spoken to LINZ (and Boffa Miskell) who are engaged by LINZ to manage the spray programme, and record below the reason they provided for minimal OR no spraying in some locations.

Hot Springs - 0 hectare – weed evident at drop off only – outside zone

Manupiura Bay 0 ha - minimal weed

Tapuakura (Curtis Road) - 0 ha - Weed identified at each end of bay, but evidence of sediment that would prevent effective attachment of diquat gel to the weed, so no spraying.

Hauparu Bay – 1 ha - weed evident at eastern end only

Whangamoa Road (west end) 0 ha – hornwort around rocks, dirty with sediment

Kuharua (Lees Pt) – 0 ha - patches of relatively dense native underwater plants – outside scope of spray programme

We understand that diquat will only adhere and be effective on healthy weed that is free of sediment. Before each spray plan is determined, divers inspect every location to determine evidence and condition and weed. We are seeking more information about this to share with our membership.

You are welcome to advise LRCA of concerns about the spray programme and we can discuss with LINZ and Boffa Miskell.

From: BML Biosecurity

Sent: Sunday, 31 October 2021 12:53 PM

Subject: Aquatic Weed Spraying - Te Arawa/Rotorua Lakes

Kia ora koutou,

Aquatic weed spraying is scheduled to be carried out in the Te Arawa/Rotorua Lakes from Monday 8th November and will continue intermittently until Friday 10th December 2021.


This work will be carried out via boat-based boom spraying using the herbicide diquat in gel form at the following sites at Rotoiti:

Wairau Bay

Ōkahutoroa Bay/Cherry Bay

Ōkawa Bay

Teal Bay

Te Weta Bay

Ōtaramarae Boat Ramp

Te Ārero Bay

Gisborne Point

Ōkere Inlet

Te Akau Peninsula

Te Waiiti Point

Te Ruato Bay

Hauparu Bay

Here is a map showing where work will be carried out.

All work is dependent on suitable weed, water and weather conditions and is subject to change without notice.


Advertisements will been placed in the Rotorua Daily Post to inform lake users of the control work.


Warning signage will also be erected at official boat ramps 24 hours before work is taking place.


If you have any questions in relation to this work, please feel free to call us on 0800 638 943 or keep up to date with treatment progress on the LINZ website.


Further updates on projected works will be provided on Sunday 7th November once we have a better idea of the weather forecast.


Ngā mihi,


 Boffa Miskell.