The Eutrophication Explorer Tool

Eutrophication refers to increasing levels of plant nutrients in a water body, and increasing risks that algae and aquatic plants will growth to nuisance levels and degrade water quality.

Eutrophication is a widespread problem in freshwater bodies in New Zealand and it impacts values such as recreation, the life-supporting capacity of waterways, and food-gathering. Regional councils are required ed to monitor and manage eutrophication in catchments and estuarine environments under the National Policy Statement for Freshwater Management) which came into effect in 2020.

The creation of the Eutrophication Explorer web-based tool is part of NIWA’s initiative to address multiple eutrophication issues. The tool utilises monitoring data and modelling predictions related to stream and estuary eutrophication.  

Eutrophication Explorer will enable communities and regional councils to explore where the eutrophication risks are in a catchment, what is driving the risks, and potential solutions. Currently the tool has a specific application to the Oreti catchment in Southland for testing purposes. 

The Eutrophication tool can:

  • Map predictions of eutrophication drivers across streams, lakes and estuaries in a catchment e.g., nutrient concentrations, flows, shade, etc.
  • Includes historical observations (e.g. nutrients, macrophytes, periphyton, estuary water quality) for comparison with the models.
  • Use built-in risk models of for macrophytes, periphyton and Estuary Trophic Index.
  • Look downstream for the location most affected by eutrophication.
  • Undertake simple scenario testing.

Testing of Eutrophication Explorer is currently underway with Environment Southland and the demonstration tool can be viewed here - You can also view a demonstration video of the Eutrophication Explorer tool in action.


Principal Scientist - Catchment Processes
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Water Quality Data Modeller