Lake Rotorua has a "surprising" amount of plastic pollution, a study has found. Photo / Ben Fraser
Lake Rotorua has a "surprising" amount of plastic pollution, a study has found. Photo / Ben Fraser
Lake Rotorua has levels of plastic pollution comparable with lakes in Europe and the United States, a new study has found.
University of Waikato associate professor and freshwater ecologist Dr Deniz Özkundakci, who helped author the newly published global study looking at plastic pollution in lakes, said the results for Rotorua were both surprising and disappointing.
The study included samples taken from 38 lakes across 23 different countries and six continents - including Lake Rotorua.
Lake Rotorua was found to have high levels of plastic pollution and the highest levels of the three New Zealand lakes in the study.
The other two lakes were Lake Taharoa in Northland and Lake Wiritoa near Whanganui.
Özkundakci said levels in those lakes were elevated but not to the degree of Lake Rotorua which showed levels of plastic pollution comparable with lakes in Europe and the US.
“However – and of concern – the density of population around Lake Rotorua is a lot smaller than some other significantly polluted lakes from the study,” Özkundakci said.
The study measured levels of small plastic particles.
University of Waikato associate professor and freshwater ecologist Dr Deniz Özkundakci. Photo / Supplied
Plastic pollution of lakes can impact sources of drinking water and can be damaging to organisms living in and around lakes. However, Rotorua’s drinking water comes from springs and bores.
Speaking to Local Democracy Reporting, Özkundakci said the study represented an early warning sign about plastic pollution in lakes, and he hoped further local studies would be carried out.
“It’s a chance for us to take action and actively safeguard our lakes from further damage.”
Özkundakci, who works with the Bay of Plenty Regional Council as chairman of the lake and freshwater science programme, said plastic debris in freshwater systems was severely understudied in New Zealand.
“The invitation to contribute to a global study was an important opportunity to get baseline data on some of our lakes.”
He said a nationwide survey of plastics would be a good starting point.
Rotorua Anglers Association president Pete Otto said Lake Rotorua was an important lake for anglers.
“We really do not want it contaminated because it’s open all year.”
He was aware of Rotorua Lakes Council using litter traps on stormwater outlets, which he said was a great thing.
Lakes Water Quality Society chairman John Gifford at Lake Rotorua. Photo / Laura Smith
Rotorua’s Lakes Water Quality Society chairman John Gifford said the study highlighted “how invasive urban development was on the environment”.
Millions of dollars have been spent in recent years on projects to improve water quality in the district and he said if that was to be maximised future development needed to be carefully considered
Rotorua Lakes Council infrastructure and environmental acting deputy chief executive Regan Fraser said it had not yet had time to digest the research and would do so alongside the regional council and Te Arawa Lakes Trust.
“The presence of plastic is not unexpected and may mainly have come from plastic litter so the study serves as a good reminder that everyone has a role to play in keeping our lakes clean and that we need to take responsibility for how we dispose of our waste.”
Included in its relevant pollution mitigation for lakes and waterways was that Rotorua’s treated wastewater passed through membrane-filtration at the wastewater treatment plant so there were no microplastics in the discharge.
There were also gross pollutant traps on key stormwater outlets from the CBD and road sweeping to prevent litter from being washed into drains.
The council had extended its kerbside recycling to lakeside communities and provided bins at reserves as well as worked to educate the public on waste responsibilities.
It was also looking to trial mesh filters in cesspits where there was a lot of litter
Rotorua mayor Tania Tapsell said any pollution in the lakes was a concern.
“The protection and preservation of our lakes is a top priority for our council and community.”
“As a council, we invest a significant amount into interventions to prevent pollution of our environment, including the many lakes that are dear to our community.
“This is a stark reminder of why people need to consume and dispose of plastics responsibly to ensure our lakes are kept clean and beautiful for future generations.”
She said she would raise the research at the next Rotorua Te Arawa Lakes Strategy Group meeting.
Te Arawa Lakes Trust chairman Geoff Rolleston said incorporating the strengths of mātauranga Māori, tikanga, intergenerational knowledge, and the rich experience of Te Arawa was of utmost importance in enhancing the health and well-being of its beloved Rotomoana.
The implementation of ‘Uwhi’ or Harakeke weed mats was one facet of a comprehensive systems-change solution, he said.
“We are well aware there is still much work to be done, but in the meantime, our support for local champions, rangatahi, critical thinkers, and change agents will significantly contribute to the advancement of these fundamental principles.”
The Bay of Plenty Regional Council was unable to respond by deadline.
Laura Smith is a Local Democracy Reporting journalist based at the Rotorua Daily Post. She previously reported general news for the Otago Daily Times and Southland Express, and has been a journalist for four years.
