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Great news for Rotorua lakes water quality
Lake Rotorua

Great news for Rotorua lakes water quality

Bay of Plenty Regional Council Media Release, 2nd October 2014
The Rotorua Te Arawa Lakes Programme partners are very pleased with the latest annual monitoring results which show most of the lakes in the programme are at, or close to, their water quality target.

Rotorua Te Arawa Lakes Strategy Group Chairman Sir Toby Curtis said the improvements in the lakes were an important result not just for Rotorua, but for New Zealand.

“At a time when many areas across the country are faced with declining water quality it is great to have several taonga improving.  It’s testament to the programme’s innovation and can-do approach,” he said.

Bay of Plenty Regional Council Chairman Doug Leeder said it was fantastic news that many of the lakes had seen significant improvement.

“Five lakes were at their target this year which is an incredible result for the programme and the community,” he said.

General Manager Environmental Delivery Warwick Murray said Lakes Rotorua, Rotoiti, Okaro, Rerewhakaaitu and Rotomahana met their water quality target and Rotoehu, Tikitapu and Rotoma were close.

“We need to recognise and celebrate the achievements to date.  But it is not the time to be complacent.  For the long-term health of the lakes we still have a lot of things to do.  For some lakes this may mean operating as business as usual and for other lakes we have major actions to complete,” he said.

“We have had a deliberate strategy of taking both short-term and long-term actions.  The short-term actions mean the community can enjoy improvements in the lakes now while our long-term actions are implemented and take effect,” Mr Murray said.

Short term actions include lake weed removal and alum dosing in streams to lock-up phosphorus while long term actions include sewerage reticulation, land use and land management change.

“Lake Rotorua is a prime example.  This is the third year we have been at or close to the water quality target.  This result is primarily due to alum dosing in the lake which is a short-term action.  For long-term improvements nutrient loads to the lake need to be reduced.

“Rotoiti has been at its target for two years now thanks to the Ohau Diversion Wall and sewerage reticulation.  It’s important to note that more reticulation is still required as well as sustainable improvements in Lake Rotorua for the long-term health of the lake.

“Rerewhakaaitu is another lake that has been at its target for the second year.  We are supporting farmers in the Rerewhakaaitu catchment to develop and implement their own catchment plan.  Landowners have done a tremendous job in reducing nutrient loss from their land and we are experiencing significant improvements in water quality as a result of their efforts.”

“Across all the lakes, the improvements are very much due to a collaborative effort.  They are only possible through the concerted efforts of the programme partners and funding from the crown and the community.”

While the annual results were promising, external factors such as climatic conditions could affect water quality from year to year.  It is also necessary to look at the long-term trend in each lake, Mr Murray said.

“The long-term trends are also extremely positive.  Nine lakes have stable or improving water quality.”

“The two lakes that have declining water quality are Tarawera and Rotokakahi and there are action plans being developed for both.  When implementation begins we hope to achieve similar success for these lakes and see improvements,” Mr Murray said.

Rotorua Mayor Steve Chadwick was very pleased with the results.

“These results are fantastic but also serve as a reminder that we can’t become complacent and that we need to keep our community with us as we continue the work of the lakes programme,” she said.

“The lakes are among Rotorua’s most valuable assets and we are striving to be known for our clean, natural environment and healthy lakes. There’s a lot of work still to be done and it’s very pleasing to know we appear to be on the right track.”

Additional information

Water quality results

  • Of the 12 Rotorua lakes in the programme the long-term water quality trend shows:
  • Water quality is improving in Lakes Rotorua, Rotoiti, Rotoehu, Rerewhakaaitu, Rotomā and Tikitapu
  • Water quality is stable in Lakes Ōkataina, Ōkareka and Rotomahana
  • Water quality shows deterioration in Lakes Tarawera, and Rotokakahi
  • Water quality in Lake Ōkaro fluctuates and continued investigation is needed.

About the programme

  1. The programme of work to improve water quality is done in partnership with Bay of Plenty Regional Council, Rotorua District Council and Te Arawa Lakes Trust to meet targets set by the community.
  2. How water quality is measured
  3. The water quality measure is called the Trophic Level Index.  It is calculated based on four areas of lake health – total nitrogen, total phosphorous, water clarity and chlorophyll-a.