More than 3,000 regional and unitary council monitoring sites have updated data available. National level analyses find Aotearoa’s freshwater systems are under pressure and facing similar challenges.

Cawthron Institute Freshwater Ecosystems Manager and scientist with the LAWA project, Dr Roger Young said the findings of this year’s LAWA River Health, Lake Health, and Estuary Health National Pictures show human activities continue to significantly impact freshwater and coastal ecosystems.

“Nutrient pollution from agricultural and urban runoff, fine sediment from erosion, and contamination from human activities affect ecosystems from rivers and lakes through to the estuarine environment,” said Dr Young.

An expert on freshwater ecology, Dr Young advised that New Zealand’s rivers continue to show widespread ecological health concerns.

“Analyses of river and stream monitoring results show two-thirds of monitored sites have impaired ecological health. Sensitive species like mayflies cannot survive at these sites, leaving only hardy species like worms and snails.

“Over a third of monitored river sites show impaired water clarity due to fine sediment, impacting aquatic life and affecting human use of these waterways,” said Dr Young.

LAWA Lake Health Science Lead Dr Mafalda Baptista outlined that of the 160 lakes monitored by councils, around two-thirds are in poor or very poor health, with the worst results found in lowland shallow lakes.

“Almost 70% of monitored upland deep lakes are in fair, good, or very good health. These lakes are generally located in less modified catchments and provide a home for very diverse aquatic life.

“In contrast, nearly all of New Zealand’s monitored lowland shallow lakes are in a poor or very poor health. These lakes are often surrounded by agricultural or urban development and face significant nutrient enrichment,” said Dr Baptista.

LAWA Estuary Health Science Lead Dr Tarn Drylie said regional and unitary councils are now monitoring a third of New Zealand’s estuaries. The data from this monitoring reveals that the places where rivers meet the sea are increasingly threatened by a changing climate and human activities.

“Concentrations of metals like zinc, copper, and lead are usually higher in estuaries close to cities, whereas high mud content is a bigger issue for rural estuaries.

“Estuary health is shaped by factors both upstream and at sea, which makes it challenging to manage. However, by reducing and controlling pollutants that run off the land, we can help some estuaries recover over time.

“A notable success is the decrease in lead concentrations in urban estuaries following the removal of lead from petrol and paints in the 1990s. This demonstrates the power of our environments to recover when we take action,” said Dr Drylie.

Looking at the data, Dr Roger Young said while it’s complex, there are examples of pollution reduction and land management actions making a difference to freshwater health.

“Improvements in ammonia and dissolved reactive phosphorus levels at some sites reflect the benefits of managing point source pollution, such as wastewater discharges. These successes suggest that focused interventions are making a difference.

“Further improvements are being seen where riparian planting and erosion control measures have been implemented, helping to reduce sediment and nutrient runoff into rivers.

“While progress is gradual, these efforts show that by taking consistent action, we can begin to reverse some of the degradation and restore water quality,” said Dr Young.

The insights on the LAWA website give New Zealanders a deeper understanding about the state of their local waterways, how this is changing over time, and how they can contribute to their care.

LAWA website link: www.lawa.org.nz

Later this year, the LAWA project will launch a new Actions for Healthy Waterways topic, sharing stories and data covering actions being taken nationwide to improve freshwater health. Groups who are actively making a difference are invited to explore the health of sites in their catchment on LAWA and visit the Healthy Waterways Register to submit their actions as a way of inspiring others.

Dataset overview

The LAWA River Health National Picture 2024, LAWA Lake Health National Picture 2024, and LAWA Estuary Health National Picture 2024 provide national level analyses of comprehensive monitoring data collectively spanning millions of individual data points. Data are only available for sites where monitoring has been conducted and monitoring sites are often located in areas at greater risk of degradation from human activities, therefore, this summary provides useful insights yet is not intended to necessarily be a complete and balanced representation of all rivers, lakes, and estuaries.