In the opinion piece ‘Set realistic targets we can achieve’, which ran in the February 26 edition of the Bush Telegraph, the author wrote: “Currently, Horizons is using a lot of modelling because no one knows what the current state of water quality is.” This statement is inaccurate.
Horizons Regional Council uses both installed monitoring equipment and physical in-person monitoring to determine the quality of water in various parts of the Horizons region, including the Tararua District. Horizons has 149 monthly water quality monitoring sites across the region, with 49 in Tararua.
Horizons does use modelling to estimate water quality at unmonitored locations, as monitoring all water quality attributes everywhere is not affordable. This modelling is based on a peer-reviewed rigorous scientific methodology.
Horizons uses models to tell us about the relationships between driver attributes and response attributes (for example, nutrients and periphyton). This modelling is informed by measured data from across New Zealand, including Horizons’ periphyton monitoring programme, and is based on a peer-reviewed rigorous scientific methodology.
Horizons also uses catchment models to link contaminant loads with sources. This is informed by the measured and modelled water quality and flow information, measured information about point source discharges and modelled information about farm losses. These models are then utilised to test policy scenarios that include a range of actions to mitigate the impact of land-based and point source activities on water, to estimate what water quality may be in the future under various freshwater policy settings.
