More than 3500 rivers, lakes and estuaries across Aotearoa are under pressure, with new data showing widespread faecal contamination and poor water quality — especially in areas of intensive land use.
The findings come from the Land, Air, Water Aotearoa (LAWA) project, which today released updated water quality results to mark World Rivers Day.
For the first time, New Zealanders can explore 20-year trends in freshwater health at around 1200 sites, thanks to long-term monitoring by regional and unitary councils.
The data shows two-thirds of monitored river sites and half of groundwater bores are affected by E. coli contamination, while two-thirds of lakes are in poor or very poor condition.
LAWA Project chairperson Dr Tim Davie said the situation varied across the country, but lakes were particularly vulnerable.
“Lakes are always going to be under pressure because they hold water for a long time, and pollutants build up,” he told 1News.
1News met Davie beside Canterbury’s Halswell River, where he noted high nitrate levels — but also signs of improvement.
“When we look at the trends over twenty years, it’s better than it was,” he said.
“We’ve got a problem with nitrate in Canterbury and across the country, and there’s a lot of action being taken to improve that.”
In the Wellington region, Dr Amanda Valois, freshwater team leader at Greater Wellington, said she was excited the data was now publicly available on the LAWA website.
“Having this access to knowledge for everybody — not just scientists — is really great,” she said.
Valois has helped test water across the region and says freshwater invertebrate communities are struggling.
“A lot of our sites are in poor health,” she said.
Davie says both urban development and agriculture are contributing to the problem.
“Anywhere where there’s intensive land use, whether that be in a city or intensive agriculture, that has an impact on our waterways.”
Dr Roger Young, Freshwater Ecosystems Manager at Cawthron Institute, said nutrient pollution was a recurring theme across rivers, lakes, estuaries and groundwater.
“There are positives evident in the data, for example ammonia and dissolved reactive phosphorus have improved at sites where point-source discharges have been upgraded,” he said.
While estuaries face pressure from metal contamination, Young said there were signs of recovery — including improvements in lead levels following regulatory changes.
The scientists hope the data will encourage New Zealanders to check the health of their local streams and take action.
“Taking time to give your stream some love is good,” Valois said.
