We’ve put together a  summary of useful research, reports, presentations and agreements related to farming in the Lake Rotorua catchment:

Collective AGM Report and Minutes

The Collective AGM has held on Tuesday 2nd May 2017.  Read and download the AGM Reports and minutes below:

Farm nutrient research reports

Here you’ll find links to a selection of farm nutrient research, presentations and reports. The Collective doesn’t endorse these reports but we think they give some useful technical background to the current nutrient policy and the potential solutions.
Find out about nitrogen and phosphorus losses from Rotorua farms, ways of reducing those losses and the impact on profit.

Report TitleAuthorsSummaryYear
BOPRC Draft Response to Collective on 'Farmer Science Priorities'BOPRC & its AdvisorsA response to questions asked by the Collective in Nov 2015. The questions covered land science, Overseer, phosphorus, lake science & policy. 2016

Final Report: Meeting nutrient loss targets on dairy farms in the Lake Rotorua catchment

Tanira Kingi, Sharon Morrell, Lee Matheson, Mike Sprosen, Stewart Ledgard and Simon ParkThis is the final report from the Rotorua dairy SFF project, including the Parekarangi field trials2015

The context and practice of nutrient mitigation on Rotorua dairy farms

Simon Park, Tanira Kingi, Sharon Morrell, Lee Matheson, Mike Sprosen and Stewart LedgardThis paper gives field trial and nitrogen modelling results from the Collective's SFF Project2015
Meeting nutrient loss targets on dairy farms in the Lake Rotorua catchment: Interim report on results from the Parekarangi Trust farm
Mike Sprosen and Stewart Ledgard (AgResearch)Interim field trial results on how different nitrogen fertiliser rates affect pasture growth, pasture quality and nitrate leaching.2014
Evolving to nitrogen discharge allocations for the Lake Rotorua catchmentWarren Webber and Gwyn MorganAn explanation of the targets and Stakeholder Advisory Group thinking behind the draft nitrogen allocation scheme.2014
Nitrogen losses from Lake Rotorua dairy farms - modelling, measuring and engagementSimon Park, Tanira Kingi, Sharon Morrell, Lee Matheson and Stewart Ledgard2014: Progress results from the Collective’s Sustainable Farming Fund dairy farm nitrogen project.2014
Rotorua NDA Impact AnalysisPerrin Ag Consultants LtdThe on-farm profit impacts from draft NDA levels are modelled for a range of dairy and drystock farms.2014
Solutions for a sustainable Lake Rotorua: the farmers’ perspectiveTanira Kingi, Simon Park and Mike ScarsbrookThe story behind the Collective’s formation and its preferred solutions such as improved on-farm management. 2012
Farmer Solutions ProjectPerrin Ag Consultants LtdA survey of farmer nitrogen mitigation preferences, associated costs and the overall economic impact on the catchment.2012
Rotorua benchmarking: challenges and progressSimon Park and Penny MacCormickAn explanation of Rule 11 nutrient benchmarking with some interim N and P loss results from 2011.2011
The efficacy of strategies to mitigate the loss of phosphorus from pastoral land use in the catchment of Lake RotoruaRichard McDowell (AgResearch)Various phosphorus mitigations methods are ranked according to effectiveness and cost.2010
Practical mitigation options to reduce
nitrogen and phosphorus losses from farms
into Rotorua lakes
Stewart Ledgard, Mike Sprosen, Matt Redding, Anwar Ghani, Duncan
Smeaton, and Rex Webby
This report summarises the research from the SFF funded project
through to 30 June 2007.
Lakes Research Title

Here you’ll find links to selection of lake research and reports. The Collective doesn’t endorse these reports but we think they give some useful technical background to the current nutrient policy and the potential solutions.

Report Title (link)Author(s)SummaryDate
Lakes Research Presentations Dr David Hamilton, Dr Grant Tempero & Hannah MuellerPresentations delivered at a public meeting on 17 November 2015 2015
Assessing the effects of alum dosing of two inflows to Lake Rotorua against external nutrient load reductions:Model simulations for 2001-2012Dr David HamiltonEffects of Alum Dosing on Lake Rotorua Water Quality2015
Phosphorus controls improve Rotorua water Dr Mike ScarsbrookDr Scarsbrook summarises the research undertaken by the university of Waikato - "Assessing the effects of alum dosing of
two inflows to Lake Rotorua against
external nutrient load reductions:
Model simulations for 2001-2012"
Monitoring and modelling to support management and policies for Lake RotoruaDavid Hamilton and Chris McBride (University of Waikato)A lake science presentation by Waikato University at Ngongotaha Hall in December 2013, including responses to farmer questions.2013
Trends and state of nutrients in
Lake Rotorua streams 2013

Paul Scholes, BOPRCNitrogen and phosphorus trends since 1992 are summarised for nine Lake Rotorua streams.2013
Use of a model to predict the effects of land use changes on nitrogen delivery to Lake Rotorua, especially the lags involved with groundwaterChris Palliser, Kit Rutherford and Sanjay Wadhwa (NIWA)The main results from NIWA’s ROTAN model, reduced to 11 pages.2011
Prediction of nitrogen loads to Lake Rotorua using the ROTAN modelKit Rutherford, Chris Palliser and Sanjay Wadhwa (NIWA)The full ROTAN report covers status quo and possible future land use scenarios and the resulting nitrogen loads on Lake Rotorua (183 pages, 9MB file)2011
Lakes TLI Results

How is TLI calculated? The TLI number is calculated using four separate water quality measurements:

  • total nitrogen
  • total phosphorous
  • water clarity
  • chlorophyll

Total nitrogen and total phosphorous are nutrients that plants thrive on. Large amounts of these nutrients in the lakes encourage the growth of algae which can lead to poor water quality. Water clarity is a measurement of how clear the water in the lake is. In general, the clearer the water, the better the water quality. Chlorophyll-a is the green colour in plants. Knowing how much chlorophyll there is in a lake gives us a good idea of how much algae the lake has. The more algae present, the poorer the water quality. The Trophic Level Index combines these four measurements into one number.

Lake Water Quality Target 2015/ 2016 Result 2014/ 2015 Result 2013/ 2014 Result 2012/ 2013 Result Stability
Rotoma 2.3 2.4 2.5 2.38 2.36 To be investigated
Tikitapu (Blue Lake) 2.7 2.9 2.9 2.82 2.75 Stable
Okataina 2.6 2.8 2.9 2.69 2.77 Stable
Tarawera 2.6 3.0 3.1 3.0 2.94 Declining
Okareka 3.0 3.2 3.3 3.30 3.15 Stable
Rerewhakaaitu 3.6 3.4 3.3 3.43 3.5 Stable
Rotoiti 3.5 3.8 3.8 3.40 3.44 To be investigated
Rotokakahi 3.1 3.7 4.0 3.63 3.69 To be investigated
Rotomahana 3.9 4.0 4.0 3.8 3.93 Stable
Rotorua 4.2 4.4 4.4 4.2 4.24 Stable
Rotoehu 3.9 4.6 4.5 3.95 3.95 Declining
Okaro 5.0 4.6 4.5 4.49 5.42 Improving
Map of Lake Rotorua Catchment
You’ll find a  full-size (12mb) version of this map here
MoU agreements
Waiora Agreement (2011) Formalising the Collective’s working relationship with the Lakes Water Quality Society.
Oturoa Agreement (2013)Facilitated by local MP Todd McLay. Led to resolving a crucial Environment Court appeal on the Proposed Regional Policy Statement.
Stakeholder Advisory Group (StAG) - Terms of Reference
View or download the document here
Land Technical Advisory Group - Terms of Reference
View the Land Technical Advisory Group – Terms of Reference here
Lake Science Review - MOU
This Memorandum of Understanding is between Bay of Plenty Regional Council, Lake Rotorua Primary Producers Collective and the Te Arawa Lakes Water Quality Society on the context, scope, timing and policy implications for reviewing science related to nutrient limits for Lake Rotorua and its catchment.