Final lake weed removal scheduled for Thursday and Friday

Final lake weed removal scheduled for Thursday and Friday

9 March 2022

A clean up will take place tomorrow and Friday to remove what’s left of washed-up weed causing a stink for users of the newly developed Rotorua lakefront.

The clean-up is a joint effort between Te Arawa Lakes Trust, Toi Moana Bay of Plenty Regional Council and Rotorua Lakes Council.

The weed was originally washed ashore by high winds related to Cyclone Dovi, however an initial clean-up using a purpose-built lake weed harvester was hampered by low summer lake levels. Much of the weed in shallow areas was not able to be recovered by the harvester.

It is hoped this week’s clean-up will round up most of the weed that can be reached from the lake edge and is creating an odour. A digger will be used from the shore, to avoid contact with the lake bed. Staff from Te Arawa Lakes Trust will be on hand to assist with manually moving weed into the digger reach area. Rotorua Lakes Council staff will then retrieve the weed from the lake edge and will be responsible for disposal of the lake weed.

The work may also cause a smell near the site for a couple of days.

Toi Moana Bay of Plenty Regional Council Lakes Operations Manager Andy Bruere says weed is always in the lake, however when exposed to shallower waters it can become a problem for lake users.  

“In this case high winds caused it to come away from the lake bed and left it stranded near the shore where it’s creating an unpleasant odour as it decomposes.”

Rotorua Lakes Council’s Sport and Recreation and Environment Manager Rob Pitkethley said more than 300 tonnes of weed has already been removed by the harvester, and some has naturally dissipated.

“It will be good to remove as much as possible of what’s left so people can continue to enjoy our redeveloped lakefront and we’ll keep working with our Rotorua Te Arawa Lakes Programme partners on plans for dealing with any future occurrences,” says Mr Pitkethley.

Environment Manager for Te Arawa Lakes Trust Nicki Douglas says the pest weed bed we are working to remove is located over a traditional koura bed.

“We are hoping to see the recruitment of native plants, establishing habitat for koura on the lakebed as a result of the removal of this weed.”

A plan is now also underway for the two councils and Te Arawa Lakes Trust to work together to ensure a more streamlined clean-up for any future lake weed stranding. This includes obtaining consent to allow the weed harvester and an excavator to work together, especially in the shallow areas to enable a quick removal of weed.

Te Arawa Lakes Trust Environment Manager Nicki Douglas says a solution the trust intends to investigate is to plant a Raupō Belt across the bay to catch the dispersed weed and prevent it from arriving at the lakefront.

“This restores the natural state of the lakebed and addresses the weed location issue. But it is also a longer term solution.”

It’s hoped this option will address any lake weed stranding caused by future summer cyclones, which are becoming a regular occurrence due to climate change.

Te Arawa Lakes Trust, Toi Moana Bay of Plenty Regional Council, and Rotorua Lakes Council are partners of the Rotorua Te Arawa Lakes Programme tasked with restoring and protecting the lakes for future generations.