Under the Resource Management Act 1991 (RMA), councils must undertake SOE monitoring in order to "effectively carry out their functions". Or simply put, to check if desired environmental results are being achieved, e.g. meeting an environmental standard or guideline.
New Zealand's regional and unitary councils collect water quality data monthly, bimonthly, quarterly or annually as part of their SOE monitoring, and air quality data for a period relative to guidelines, e.g., daily for PM10. This SOE monitoring data is used to: 1) detect changes in environmental conditions and trends, including their significance; and 2), to detect changes in the state of the environment following the implementation of council plans and strategies. Council SOE monitoring is done to serve both council and national environmental reporting needs (see State of the Environment (SOE) reporting).