Healthy Rivers Plan Change 1 Expert witnesses

The Healthy Rivers Waikato Regional Plan Change 1 aims to manage both point source and non-point discharges linked to agriculture via management of nitrogen, phosphorus, sediment, and bacteria entering the Waikato and Waipā rivers over time. Implementation of this Plan Change will enable the protection and restoration of the health of the water bodies over the short term and long term, giving effect to the Waikato Vision and Strategy. Hearings Commissioners heard more than 359 hours of evidence over 59 days last year. As well as reading more than 1100 submissions, they heard evidence from 360 different parties over the course of the hearings and had 199 expert appearances. Almost all of Streamlined Environmental’s team was involved in the provision of expert advice on the proposed Plan Change.

Dr Ngaire Phillips prepared and presented evidence on behalf of the Department of Conservation on shallow lakes within the Waikato-Waipā catchments. Evidence covered the values and significance of lakes, including the ecological condition and restoration potential of shallow lakes. Concerns of the approach outlined in Plan Change 1 for lake management were also provided along with recommendations to address appropriate management of shallow lakes.

Dr Tim Cox was also an expert witness on behalf of Beef and Lamb NZ. Tim provided expert evidence on catchment modelling and analysis of nutrients in the Waikato and Waipā River basins. Streamlined Environmental’s inhouse Contaminant Allocation Simulation Model (CASM) (developed by Tim) was used for generalised catchment modelling. Tim was able to provide evidence on the likely causes to nutrient (nitrogen and phosphorus) loading in the river basin from pastoral agriculture lands, horticulture lands, industrial discharge, sewerage discharge, residential septic tank leaching, and direct deposition to the waterways. This allowed an in depth understanding to nutrient issues within the basin and investigation of potential mitigation strategies for long-term targets to be achieved.


Dr Rebecca Eivers was an expert witness on behalf of Auckland Waikato Fish and Game, providing and presenting evidence regarding sources and pathways of farming contaminants. Rebecca’s expertise in water quality and freshwater resource management issues, coupled with expertise in mitigation measures, allowed expert advice on both evidence of contaminant issues and relevant mitigation practices.

Dr Chris Data provided expert advice to Beef and Lamb NZ by drafting evidence relating to E. coli standards proposed for different parts of the Waikato-Waipā catchments. As well as evidence relating to E. coli standards, Chris also outlined proposed rules to achieve those standards. Chris crafted evidence that challenges generally accepted norms about the fate and transport of pathogens from pastoral land to receiving waters and methods to mitigate these.

Healthy Rivers is the first step in an 80-year plan for improving the water quality and health of rivers in New Zealand. Streamlined Environmental was able to contribute to the knowledge of current conditions of the Waikato’s water quality and provide recommendations for mitigation that can be implemented for assisting in the achievement of healthy rivers in New Zealand.
Amongst the recommendations in the Hearing Panel’s decision document which reflected the contributions of SEL staff included the greater recognition of the lakes and wetlands than had previously been considered by the proposed plan change. In addition, further modelling undertaken was acknowledged as adding to the development of a more robust approach to setting nutrient limits within catchments and sub-catchments.