Fraser said immediate containment was in place, but full recovery “may take weeks or months depending on environmental conditions”.
Though fast-moving, choppy water helped diesel evaporate, recent rainfall had caused seepage from the soil.
He said council staff continued to monitor the streams to track the environmental impacts.
The response had cost more than $30,000 in staff time and $6000 for equipment, Fraser said.
Three council staff were on site by about 3am on August 15, about an hour after the fatal crash.
In darkness and rough terrain, they quickly deployed 3m booms across accessible points of the streams.
Because diesel is lighter than water, both floating absorbent booms and curtain booms were positioned to trap the fuel and stop it from spreading.
The booms, made of hydrophobic plastic, acted like filters, soaking up to 30L of oil before sinking when full. They were checked daily and replaced as needed to remain effective, and were still in place this week.
A flexible pipe, known as a flexi flume, was also installed below the site to divert stormwater and reduce the mobilisation of diesel.
Fraser said no fuel had been observed as far downstream as Whakarewarewa or Lake Rotorua.
Booms are still on the Kauaka and Puarenga Streams two weeks after 16,000 litres of diesel was spilt. Picture taken on August 24. Photo / Supplied
Whakarewarewa Living Māori Village general manager Tanya Robinson said several people had reported diesel smells coming from the awa (river) in recent days, a development she described as “absolutely a concern” for the village.
The Puarenga Stream running through Whakarewarewa Village was a taonga (treasure).
“In many ways, it’s the lifeblood of the village.
“It’s central to the kōrero we share on our tours, and no one wants to see serious impacts on the environment,” Robinson said.
People should avoid swimming in the stream at this time, she said.
Robinson said it was fortunate the spill happened outside the peak season of penny diving, the tourism attraction’s famous tradition where children leap into the awa to collect coins tossed by tourists, carrying them in their mouths.
Queen Elizabeth II and the Duke of Edinburgh watch children dive for coins from the bridge at Whakarewarewa during the Royal Tour of New Zealand 1953-54.
She said the community hoped for a clean river by summer, so “that our tamariki can swim in [the awa] and be part of the legacy of penny diving”.
A spokesperson for MOVe Fuel, the company that owned the crashed tanker, said it was working with the regional council, Te Arawa Lakes Trust, iwi and environmental experts from PDP to minimise the impact of the spill.
Environmental experts had carried out soil and water sampling, ecological surveys and the safe removal of contaminated soil.
No effects on marine life or vegetation had been observed, as of August 26 they said.
Company representatives attended a hui on August 22 to engage with iwi and the local community.
MOVe would continue working alongside tangata whenua to define recovery goals that reflected ecological and cultural values.
The spokesperson thanked the community, iwi and the many groups involved for their support and collaboration through the clean-up and recovery effort.
They said monitoring of waterways, marine life and vegetation would continue for a period.
If diesel is seen or smelt, the public is advised to avoid the Kuaka, Tureporepo, and Puarenga stream areas and report any observations to the regional council’s 24/7 Pollution Hotline on 0800 884 883.
Police continue to investigate the crash on behalf of the Coroner.
Annabel Reid is a multimedia journalist for the Bay of Plenty Times and Rotorua Daily Post, based in Rotorua. Originally from Hawke’s Bay, she has a Bachelor of Communications from the University of Canterbury.