The Freshwater NPS 2011 was amended and replaced in 2014 to introduce the national objective framework as a way to help regional councils apply the requirements of the Freshwater NPS in a consistent way across the country.
The national objectives framework specified the process regional councils must use to set freshwater objectives. Objectives must, as a minimum, be set for two compulsory values: ecosystem health and human health for recreation. Some national bottom lines were introduced for the compulsory values. Objectives must be set above the national bottom lines.
The attributes (eg, total nitrogen, nitrate toxicity, periphyton) and their associated national bottom lines in the Freshwater NPS were selected on the advice of specialist science panels.
The scientists took part in a range of expert panels to consider:
- the critical attributes of water quality for which objectives need to be set
- the critical levels for each attribute
- an appropriate level to set a bottom line before an ecosystem tipping point.
The proposed attributes were considered by a reference group of water users and managers which provided advice to officials on their workability.