Iwi seeks plan about lake weed

The Onepoto intake structure. During Cyclone Gabrielle the water was one metre over the orange line, says chief wholesale officer Tracey Hickman. Picture by Zita Campbell

Tūhoe say Genesis has ignored a promise to engage with them on an invasive weed growing in Lake Waikaremoana, in northern Hawke’s Bay.

“We spoke to them, we wrote to them, and they ignored any response,” said Tūhoe Te Uru Taumata chief executive Kirsti Luke.

The iwi want to make a plan to eradicate the invasive weed Lagarosiphon in Lake Waikaremoana, which is co-owned by Māori and the Crown (DoC), and then leased from the Crown to Genesis for energy production.

The weed contamination issue made headlines in early January, when Te Urewera Board deputy chair Chris Finlayson accused Genesis of neglect.

The energy company had agreed to meet with iwi on the issue, but “it has been months and still no response”, said Luke.

The spread had been caused by lake levels being too high and lowered too quickly, causing a bloom to happen through sunlight and oxygen exposure, she said.

“It spreads it to a level of invasion.”

Luke said the power company had ignored all communication from them.

Genesis media and communications manager Chris Mirams said when Lagarosiphon wa exposed during low lake level events, extreme dryness occurred, the plants died and exposed shorelines resorted initially to fine sediments. 

"Over time some terrestrial plants colonise beaches until lake levels rise again. 

"This is typical of the dynamic nature of the Waikaremoana shoreline where lake levels vary by 3 metres under the current operational regime. This is a natural process and does not cause the spread of Lagarosiphon."

The company had an operational plan using “a range of tools, tactics and monitoring approaches” that worked well until 2018, he said.

Genesis had no data on the extent of the current weed incursion.

“However, a NIWA dive survey funded by Genesis in 2019 did not detect any Lagarosiphon on survey lines.”

During a recent media tour of the power plant, a Genesis worker said the weed had been brought in on outboard motors and boat trailers.

Finlayson has also raised the weed issue, writing to Genesis on February 12.

“I had a Zoom meeting with the general manager to discuss the possibility of board members of Te Urewera and Genesis meeting at Lake Waikaremoana to discuss issues arising from the lease by Genesis.”

The letter suggested that both parties could meet to set out their respective positions and find a positive resolution.

“I’ve never had a reply to that letter, which is somewhat disappointing,” Finlayson said.

He said he wanted to meet with Genesis to sort out the issues between the two parties in person and not through the media.

Mirams said they had not received any communications from Finlayson. 

It was important to remember the lake was in Māori ownership and that the Crown held the lease for the lake, he said.

“Genesis has an operating easement to store and release water to operate the power scheme. It also means Genesis has very limited ability to actively manage weeds in Lake Waikaremoana.

“Prior to the Tūhoe Treaty Settlement (2014) there was a long history of significant collaborative efforts from many organisations, including Genesis, to control weeds in the lake.”

He said Genesis helped fund a response to an incursion of the weed from 2012 to 2016, including dive teams using suction dredging, hand weeding and lake-wide monitoring that showed significant progress in managing the incursion.

Genesis sent a proposal for further weed control around the lake shore in 2021 to Te Uru Taumatua (TUT) operations and followed up several times, and offered to fund this work, he said.

“This offer was not taken up.”

Wairoa Mayor Craig Little said if the weed issue had been caused by management of the water level, then Genesis did have a responsibility to help Te Uru Taumatua.

“If they’ve made a lot more money out of the lake levels being so high — high lake levels obviously equate to high dollars — then they need to try to work with the local iwi to actually see what they can do together. I think that would be a good partnership.

Mayor Little said Te Uru Taumatua were the first ones that came to their community in Cyclone Gabrielle.

“They dropped $500,000 into our mayoral fund. That’s the largest contribution ever made, and it was about putting people back into their homes,” he said.

“At the end of the day, they’re really struggling for funds and resources, and they need all the help they can get, because they’re doing a great job in encouraging people to come back.”