Drinking water for 40 percent of New Zealanders comes from aquifers, which also feed rivers and lakes. But nitrogen is tainting Aotearoa's groundwater. What's that pollution doing to the complex microbial eco-systems down there? Here is an interesting article from the University of Auckland: https://www.auckland.ac.nz/en/news/2020/04/21/secret-life-of-our-aquifers.html