The Ōhau channel diversion wall was built in 2008 to divert polluted nutrient-rich water from Lake Rotorua, which otherwise flowed into Lake Rotoiti through a small channel, but critics say holes from corrosion allows water through. Photo: Supplied
Rising discontent at the deterioration of the Ohau channel diversion wall spilled over this week with the district and regional councils at loggerheads.
On Monday RNZ reported on problems with the wall, which was meant to divert polluted nutrient-rich water from Lake Rotorua, stopping it from flowing into Lake Rotoiti through a small channel.
Following this reporting, a letter of demand was given to regional council chief executive Fiona McTavish and chairman Douglas Leeder, insisting the wall be fixed and claiming the council was in breach of its consent to build and maintain the wall.
The demand for action was lodged by the Lakes Water Quality Society and Lake Rotoiti Community Association. It was supported by letters from Ngāti Pikiao Environmental Society and the iwi council of elders Te Kaunihera Pakeke o Ngāti Pikiao, local charter boat operator Pure Cruise Ltd, tourist businesses Hells Gate and Lake Rotoiti Hot Pools, and the Lake Rotoiti Classic and Wooden Boat Association.
Rotorua Lakes Council mayor Tania Tapsell said she found the situation very concerning.
"It's very disappointing that there's been 11 years now since this issue was first identified," she said.
Tapsell was shocked when she saw footage of how badly the wall had deteriorated and said in her opinion the regional council was in breach of their obligations.
"Who steps in when they are the regulator? They would normally be the ones who would tell other people 'You have to fix it', now we are going 'can you just fix your own asset'."
However, the regional council reiterated that the holes in the wall, though unfortunate, were not creating a major source of pollution for Lake Rotoiti.
Council chair Doug Leeder said if tens-of-millions were to be spent on protecting Lake Rotoiti, the council needed to know it was going on the right interventions.
He also said the construction of the wall, which he agreed was a problem, was carried out by the in-house engineering team at Rotorua Lakes Council.
"So the issues of the specification of the materials that were used in the wall, which were clearly sub-optimal, that responsibility doesn't rest just with the regional council, that responsibility rests with RLC [Rotorua Lakes Council] as well," he said.
Lake Rotoiti, which is connected to Lake Rotorua by a small channel. Photo: RNZ/ Libby Kirkby-McLeod
The letter of demand for action was lodged with the Bay of Plenty Regional Council on Monday and was supported by a range of local groups, iwi, and businesses.
Signed by Lakes Water Quality Society chair Jim Gifford and association chair Peter Browning, the letter claimed that the regional council was not doing enough to maintain the wall and protect the water quality of Lake Rotoiti.
"Regional Council response to date has been tardy and inadequate given the ongoing serious detrimental changes to the lake, such as the increased occurrence of algal blooms and reduced clarity," it said.
The letter said they understood that the regional council was wanting to defer action on repairs, possibly indefinitely.
"Further delays by the Regional Council in taking the position that the repairs to the Wall are not urgent is clearly a breach of your own policies, plans, responsibilities and obligations to the Community."
In the letter of demand, the groups said the regional council was in breach of its resource consent to build and maintain the wall in three areas.
"The purpose of the wall is no longer being met as designed, the wall has not been maintained in good condition for the term of the consent, [and] the Regional Council has failed to meet the reporting requirements."
Lakes Water Quality Society chairman John Gifford, at Lake Rotoiti. Photo: RNZ/ Libby Kirkby-McLeod
Leeder said the council did not believe it was in breach. He said the purpose of the wall was to keep polluted water from Lake Rotorua out of Lake Rotoiti but Lake Rotorua's water was no longer such a problem.
"As of today, the latest advice we have is that the water quality from Rotorua - because of the interventions we have put in place - is now not a major determinate of the water quality in Lake Rotoiti," he said.
Leeder said other issues, such as major rain and wind events and rising temperatures which encourage bacteria to grow, could be more to blame for the declining water quality in Lake Rotoiti.
He said the council was making decisions based on "the best science" but agreed the wall having holes so shortly into its 50-year lifespan was concerning.
"It should not have occurred," he said.
Local businesses owners say their livelihoods depend on the health of Lake Rotoiti. Photo: RNZ/ Libby Kirkby-McLeod
Supporting the claims in the letter of demand, Pure Cruise Ltd's director Matt Horder said his group had noticed a decline in Lake Rotoiti's water quality.
"A decline that directly correlates with the continued deterioration of the diversion wall. This is not only a serious environmental issue but a growing concern for those of us whose livelihoods depend on the health and appeal of our freshwater environment," he said.
Hell's Gate general manager Paul Rayner said the livelihood of tourism businesses in the area relies on the health and reputation of the local lakes.
"There is no justification for further research delays," he said.
Ngāti Pikiao Environmental Society co-president Pia Bennett said issues like failures in the diversion wall were a symptom of a bigger problem.
"These developments reflect growing concerns about the governance, protection, and
stewardship of freshwater in the Te Arawa Rotorua lakes region," he said.
Leeder said the regional council took community views seriously and was putting the issue on the council's agenda to discuss at a future meeting.
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