Target 6.3 sets out to improve ambient water quality. Ambient water quality data provide a picture of water body health over time, and help identify pollution hot-spots. This can inform the enforcement of pollution laws and discharge permits. UNEP (GEMS/Water) is the custodian of indicator 6.3.2.

INDICATOR 6.3.2 AT A GLANCE

The indicator tracks the percentage of water bodies in a country with good ambient water quality. “Good” indicates an ambient water quality that does not damage ecosystem function and human health according to core ambient water quality parameters.

Overall water quality is estimated based on a core set of parameters which inform on major water quality impairments present in many parts of the world:

• dissolved oxygen (surface water)

• electrical conductivity (surface water and groundwater)

• nitrogen/nitrate (surface water and groundwater)

• phosphorus (surface water)

• pH (surface water and groundwater)

The methodology calls for in-situ measurements of these water quality parameters. The measured values are 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.