The doors to our Whitianga and Paeroa offices will be closed for the summer break from 4pm on Friday, 20 December, while our Taupō and Hamilton offices will close for the summer break at 1pm on Tuesday, 24 December. All offices will reopen on Monday, 6 January 2025. To report air or water pollution, unsafe water activities in or on a river, lake or harbour, or make a general enquiry or information request during this time, call us 24/7 on 0800 800 401.

Close alert

Modelling E. coli in the Waikato and Waipa River Catchments Development of a catchment-scale microbial model

TR 2018/62
  1. Services »
  2. Publications »
  3. TR2018/62

Report: TR 2018/62

Author: Annette Semadeni-Davies, Sandy Elliott, Sharleen Yalden (National Institute of Water & Atmospheric Research Ltd (NIWA)) 

About this report

This report was commissioned by the Technical Leaders Group for the Healthy Rivers Wai Ora Project Report No. HR/TLG/2015-2016/2.6

The report presents the development of three models developed to provide input data to a farm cost model to evaluate the costs associated with mitigating farm practices to reduce E. coli loads.

Read or download the report

Modelling E. coli in the Waikato and Waipa River Catchments Development of a catchment-scale microbial model [PDF, 2.1 MB]

Contents
Executive summary
1 Introduction
1.1 Preamble
1.2 E. coli
1.3 Scope
2 Methodology
2.1 Input data
2.1.1 Drainage network and monitoring stations
2.1.2 Catchment characteristics
2.1.3 Land use
2.1.4 Point sources and farm dairy effluent inputs
2.2 Calibration data
2.2.1 Annual median concentrations
2.2.2 Mean annual loads
Rating curve method
Ratio method
2.3 E. coli load models
2.3.1 Detailed load model
2.3.2 Calibration method
2.3.3 Coarse load model
2.4 Concentration model
2.4.1 Concentration estimated at unmonitored sites
2.4.2 Prediction of concentrations for future scenarios
3 Results
3.1 E. coli load models
3.1.1 Calibration
3.1.2 Detailed load model
3.1.3 Coarse load model
3.2 E. coli current concentration model
4 Model uncertainty
5 Recommendations for further work
6 Conclusions
Acknowledgements
References
Appendix A - Mitigations for microbial load reduction
Appendix B - Point sources
Appendix C - Calibration data: Concentration
Appendix D - Calibration data: Loads