Sources of nutrients in rivers
Key Points | Report Card | Technical Information | Data
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What is happening in our region
Generally, the background (natural) loads of the plant nutrients nitrogen and phosphorus in our rivers are low.
Most of the nutrients in our water come from human activities, which can be separated into point and non-point sources.
Nitrogen loads from point sources are low in the four major Waikato rivers and are similar to background levels. But the nitrogen loads from non-point sources are high, particularly in the intensively farmed Waitoa and Piako River catchments. The loads tend to be highest in areas of intensive dairy farming.
Usually, the phosphorus loads from point sources and non-point sources on developed land are similar to the background loads. But during 1993 - 1997, the point source load of phosphorus to the Waitoa River was particularly high. In 1998, the load fell to about one-quarter of that shown in the graph below (but at the same time the point source load of nitrogen to this river increased by about 10 percent) because of changes in waste water management at a site on the river.
The graphs show the amounts of nitrogen and phosphorus in four major Waikato rivers that come from background sources, point sources, or developed land.
- View the graphs’ data.
- Data were collected from 1990 – 96 in the Waikato River and 1993 – 97 for the Hauraki rivers (Waihou, Piako and Waitoa).
Why nutrients sources are important
This indicator is based on the amounts (loads) of nitrogen and phosphorus going into our rivers and where they come from. Nitrogen and phosphorus are both plant nutrients. In excessive amounts, these nutrients can cause nuisance growths of water plants and algal blooms. This can determine how suitable the rivers are for swimming, and for plants and animals to live in.
What Environment Waikato is doing
- Environment Waikato monitors the nutrient levels in rivers to update this indicator and to assist with policy making and resource consent decisions.
- Environment Waikato has classified different waterbodies into different management classes. We have established these classes to manage water use and protect water quality values.
- Environment Waikato manages and requires the monitoring of resource consents to discharge wastewater to rivers, or to dam or divert rivers and streams.
- We support Care groups in the Region that are involved in riparian management such as planting and fencing.
- Over 217 Rivers and Us programmes involving more than 100 schools have been run.
- Environment Waikato's Clean Streams project provides advice and financial support to encourage and support farmer efforts to reduce the impacts of farming on waterways through fencing and planting waterway margins.
- We provide environmental information, including practical land management guidelines.
- We support voluntary guidelines and codes of practice such as the NZ Fertiliser Manufacturer’s Research Association’s Code of Practice for Fertiliser Use (code of practice).
Find out more about the water provisions in our Regional Plan.
What you can do to help
- Fence off streams, rivers, swamps, wetlands and seeps to prevent stock access.
- Plant banks of waterways to help stabilise the banks and trap nutrients.
- Make sure dairy shed effluent irrigators are operating effectively and are moved frequently to prevent ponding and runoff into waterways.
- Avoid break-feeding or mob-stocking close to waterways, especially in wet weather.
- Form a Care group with your neighbours to discuss and implement better land management practices to protect your local river and stream.
- Install stormwater detention areas in new subdivisions to improve water quality (less silt and animal faeces reaches the rivers and streams). Find out more about activities requiring consents from Environment Waikato.
More information
More detail on this indicator, including how and where Environment Waikato collects this information, is available in the Technical Information page.
Useful links
Related indicators