Monitoring ambient water quality (indicator 6.3.2)
Indicator 6.3.2 "Proportion of bodies of water with good ambient water quality"
What and why?
The indicator looks at the resulting quality in the receiving water bodies, and as such indirectly captures the impacts of untreated wastewater and runoff from urban and agricultural areas.
Overall water quality is estimated based on a set of five parameters that inform the major water quality challenges present in many parts of the world: dissolved oxygen, nitrogen, phosphate, electrical conductivity and pH. The methodology calls for in-situ measurements of these water quality parameters. The measured values are then compared to national target levels for the different parameters, and if values do not exceed the target level, the water body is classified as good.
By monitoring indicator 6.3.2, policy- and decision-makers learn which waters that are the most polluted and can target interventions accordingly. If a country lacks national target levels for these five parameters, the monitoring of 6.3.2 may be a good opportunity to develop such targets.
How to progressively Monitor?
Data on water quality are likely to be collected by the ministry of environment or the ministry of water, who could start looking at the five core parameters at existing sampling stations, and as available resources and capacity increase, more sampling stations could be added and the sampling frequency increased.
Additional parameters could also be added to the indicator, focusing on those of special concern in a given water body. Earth observations are increasingly used to estimate ambient water quality in a cost-effective manner.
The United Nations Environment Programme (UN Environment), on behalf of UN-Water, compiles country data at the global level and supports countries in their monitoring efforts.