About 60 people from ‘Extinction Rebellion’ gathered at parliament to demand that the government raise the country’s freshwater quality standards.
The protest follows a series of demonstrations by climate activists across the globe.
Spokesperson Jamie Horam said the environmental cost of dairy farming should outweigh the economic benefits it brings to the country.
“We tipped sour milk down parliament steps because our milk in New Zealand has a sour side.
“We call it white gold but, really, it’s quite sour. The sour side that is that our rivers and our lakes are deteriorating really fast and essentially all of our freshwater species are endangered.
“This was to make a point, that our milk has gone sour.”
About 15 people were dressed as cows and several others dressed as peasants.
“It’s quite relevant for us because its small-scale, regenerative, peasant-style farming that we need to return to in New Zealand to ensure that we have high-quality land and high-quality waters for future generations.”
On Saturday the group will perform a human wave at Waitangi Park in the capital to symbolise the coastal inundation Wellington will experience in the future due to sea level rise.