Integrated Catchment Management

Faecal bacteria in the Motueka River

 Research Status: Ongoing
Cows in the Motueka River

Cows in the Motueka River


Storm events can mobilise and transport large amounts of contaminants from sources of pollution on land, threatening water uses downstream. Microbes such as bacteria, viruses, and protozoans of faecal origin that are mobilised during storm flows impact bathing and shellfish harvesting (and shellfish aquaculture) in coastal waters that receive contaminated river plumes.

The Motueka River has a range of land uses over its 2000 km2 catchment, including pastoral farming. The latter is expected to be the dominant source of faecal microbes in this river, rather than human sewage.

Research Approach

We have examined faecal indicator bacteria, turbidity (water cloudiness) and flow in the Motueka River, in order to better understand sources and transport of faecal pollution and downstream effects.

Continuous flow and turbidity are recorded continuously at Woodmans Bend near the mouth of the Motueka River. An automatic sampler is programmed to ‘trigger’ sampling when river level rises above a threshold. We intercepted autosamples collected for sediment analysis over storm events for a calendar year (2003-2004), and sub-sampled for analysis of the faecal indicator bacterium, E. coli as an index of faecal pollution. Regular (monthly) sampling for E. coli in the river was already underway (and is continuing).

Research Results

The Motueka River is fairly unpolluted by faecal microbes compared to New Zealand rivers generally, with concentrations almost always suitable for swimming under baseflow conditions. However, as has been found elsewhere, faecal contamination levels were very much higher (E. coli bacteria concentrations 100 times or more higher) during stormflows and tended to be higher on the rising limb of the storm events (when water was usually not suitable for swimming) than when water level was falling. Swimming during storm events is not recommended - and not just because of the microbiological status of the water!

As we expected, almost all (98%) of the annual E. coli load (E. coli per year) delivered to Tasman Bay is exported during rainstorm events.

The NIWA E. coli data has been used to calibrate a model on river microbial dynamics developed by Jeremy Wilkinson, based, until recently, at Cawthron Institute.

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Recent Publications

Year Title File Size
2012 A Summary of Outcomes and selected formal publications from the Integrated Catchment Management (ICM)research programme:2000 – 2011
pdf       1.08MB
2011 The Sherry River – a Success Story 2.97MB
2011 Facilitating voluntary action to reduce rural land use impacts in the Motueka River catchment pdf       3.59MB
2011 Integrated Catchment Management – Special Issue of the NZ Journal of Marine & Freshwater Research  
2009 Sherry River Water Quality Investigation 2007–08 pdf       1011KB
More publications on this topic »
All ICM Publications »

Recent Presentations

Year Title File Size
2011 Facilitating voluntary action to reduce rural land use impacts in the Motueka River catchment. pdf       26KB
2008 Modelling catchment indicators in the coastal environment pdf       2806KB
2006 Bugs n mud: E. coli, turbidity and flow relationships for the Motueka River. ppt       1138KB
2006 Faecal microbial pollution of waters. pdf       196KB
More presentations on this topic »
All ICM presentations »

BMPs, BEPs and Guidelines

Title Description
Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas From guide:
The Microbiological Water Quality Guidelines for Marine and Freshwater Recreationa...More »  
Drinking–water standards for New Zealand From website:
The Drinking–water Standards for New Zealand 2005 contains comprehensive i...More »  
Dairying and the Environment: Managing Farm Dairy Effluent From manual:
The purpose of this manual is to assist dairy farmers and farm management special...More »  
A Guide to Managing Farm Dairy Effluent – Tasman/Marlborough From booklet:
This booklet provides best management practices for the main systems currently o...More »  
Farm Dairy Effluent: Best practice guidelines From website:
To help dairy farmers manage farm dairy effluent, the Farm Dairy Effluent bookle...More »  
All BMPs, BEPs & Guidelines »

Primary Contacts:

Image - Rob Davies-Colley Rob Davies-Colley  EmailSend email to r.davies-colley
Phone: (07) 856-1725
Fax: (07) 856-0151
More details»
National Institute of Water and Atmospheric Research (NIWA)
water quality (esp. optics of water, faecal indicator bacteria), stream habitat, riparian ecology
Image - Rob Merrilees Rob Merrilees  EmailSend email to r.merrilees
Environmental monitoring
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Page last updated Monday, 16 March 2009

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