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Assessing the Relative Importance of Faecal Pollution Sources in Rural Catchments

Report: TR2006/41
Author: Bob Wilcock (NIWA)


There is increasing concern about the levels of faecal pollution in our rivers and streams and recent reviews have addressed aspects of faecal runoff from rural catchments by examining pathways and models for predicting loads to surface waters . What has not been done is to compile a list or table of sources of faecal organisms that can be used in modelling and risk assessment exercises. This report, initiated by Environment Waikato, examines key sources of faecal pollution in the rural landscape, and the most appropriate best management practices (BMPs) for ameliorating waterway pollution. It also serves as a resource document by listing key references describing faecal pollution sources and pathways in rural settings.

The report focuses on the Waikato region but draws upon data from a wide range of sources. Because dairying is the major form of intensive agriculture in the Waikato the brunt of this report will deal with faecal sources from that land use. It should also be noted that the practice of spreading chicken litter on pasture as a form of fertiliser is receiving increasing attention because it may be a significant source of pathogens. Data confirming this is not readily available and more work is needed to identify levels of indicator organisms and pathogens, and hence risk of disease transmission. Two other points for consideration are: direct versus indirect faecal contamination; and yields versus concentrations.


Assessing the Relative Importance of Faecal Pollution Sources in Rural Catchments
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Table of contents

Executive Summary iv
Introduction 1
1 Introduction 2
1.1 Direct versus indirect faecal contamination 2
1.2 Yields versus concentrations 2
2. Key source areas and appropriate BMPs 4
2.1 Background levels on pasture 4
2.2 Runoff from pasture 5
2.3 Direct deposition in the stream channel 7
2.3.1 Grazing in stream channels and riparian zones 7
2.3.2 Cattle crossings 8
2.3.3 Water fowl 10
2.4 Farm laneways 10
2.5 Oxidation pond discharges 11
2.6 Runoff from effluent irrigation 12
2.6.1 Effluent irrigation loading to land 13
2.7 Wetland and seepage zones 15
2.8 Surface and sub-surface drains 15
2.8.1 Example 3 19
2.9 Stand-off pads and feed pads 19
2.10 Wintering pads and barns, herd homes 20
3. Summary 21
4. Acknowledgements 25
5. References 25