Freshwater and Estuaries research projects

Read more about our freshwater and estuaries research. 

Many New Zealand lakes are suffering from nutrient enrichment, causing potentially toxic blooms of blue-green algae. NIWA is testing a range of methods to manage phosphorus release from lake sediments – including sediment-capping agents.
Gathering, eating and sharing wild kai (food) has always been a very important part of Māori culture and wellbeing - this research project aimed to characterise the risks associated with consuming kai collected from rivers, lakes and coastlines.
This project involves the development of a computer-based framework for freshwater models. The framework will be tested to proof-of-concept stage.
Many of New Zealand's rivers fail to meet national guidelines for nutrient levels. NIWA has developed the Catchment Land Use & Environmental Sustainability (CLUES) estuary tool to predict the effects of land use on estuarine nutrient concentrations.
Last updated: 
1 April 2021
Understanding the relationship between hydrological processes and stream ecology is vital for the sustainable management of the water sources that support Lake Ellesmere.
NIWA has produced revised safe levels of dissolved oxygen for fish, which will help inform future environmental planning and resource consents and help to keep New Zealand rivers full of healthy fish.
Streams play a key role in the ecosystems of New Zealand’s unique landscape. They feed and link together freshwater sources, maintain good water quality and support habitats that sustain our biodiversity.
Changes to the local environment and over harvesting have damaged shellfish populations in many estuaries. These projects examine the most effective way to restore these habitats and allow healthy populations of shellfish to return.
The giant kōkopu is a native whitebait species considered rare and vulnerable. NIWA is working with Mahurangi Technical Institute and environmental consultancy Boffa Miskell to test the feasibility of reintroducing giant kōkopu to Nukumea Stream, north of Auckland.
NIWA has developed an Urban Stormwater Contaminant (USC) model to enable urban planners to predict sedimentation and heavy metal accumulation in estuaries and identify problem areas in order to target mitigation measures.
Contamination of shellfish by faecal microbes is a health hazard to the consumer and so is of particular concern to the commercial producer.

This project will demonstrate the commercial feasibility of producing bio-oil by the conversion of algae biomass that has been grown in wastewater treatment facilities. In particular we aim to maximise algae production in High Rate Algal Ponds (HRAP) by adding carbon dioxide, and demonstrate energy efficient conversion of algal biomass to bio-oil.

This project aims to increase our knowledge of aquatic ecosystems and their restoration, and apply this to degraded streams, rivers, lakes and estuaries.
Estuaries are highly valuable systems that provide enormous economic and cultural benefits to all kinds of people. However, expanding human populations and urban development around estuaries is increasing contaminant loads, with metals and polycyclic aromatic hydrocarbons (PAHs) accumulating in sediments.

Farmers rely on irrigation, but water is a limited resource and little is know about how to manage it best. NIWA has developed a hydrology and soil science model to show how much to water, and when, to get the best results.

New Zealand's rivers and streams, and the diverse fish that live in them, are worth protecting. But the question of which species prefer to live where was unanswered until NIWA completed this major survey.

The kōaro was once abundant in the Te Arawa lakes near Rotorua in New Zealand’s North Island. NIWA has assessed the viability of restoring this species in the region.