Overseer and regulatory oversight: Models, uncertainty and cleaning up our waterways

Water quality is a serious environmental issue in Aotearoa New Zealand, and nutrient losses from farms have an impact on our rivers, lakes and estuaries. As the country looks to improve the state of its waterways, an important part of the regulatory puzzle is how we manage pollution sources.

Overseer is currently the most commonly used model for calculating nutrient losses in New Zealand. It is used by farmers to improve nutrient use on farms, and more contentiously by regional councils to help inform regulations around water quality.

The Commissioner considered that an independent investigation of this model could help inform the debate around its role in improving water quality, and identify how Overseer can be improved to be better suited for use as a regulatory tool.