Cities should select the most appropriate measure from the options below, based on
whether the most significant local water bodies are streams, lakes or coastal areas.
Artificial and/or channelized water bodies may be considered as appropriate. For basic
completion, select at least one major stream, at least three large lakes, or the coastal
area. For advanced completion, include all major local water bodies (streams of at least
fourth order in size and any lakes of at least 4 hectares in area) and coastal areas.
For streams: Measure the difference in nutrient retention from raw water samples taken
at predetermined upstream and downstream sampling locations of primary* streams in
the city.
For coastal areas and lakes: Measure the total area of eutrophication for coastal areas
and large lakes.
When there are no large aquatic systems within the cities’ boundaries, cities may
consider smaller streams and lakes in boundary, or may measure quality in 3 systems
within 10 km from the city boundaries, in an area upstream (control site) and
downstream.
Sampling should take into account the expected temporal and seasonal changes in the
environment. Sampling protocol (i.e. frequency of measurement, sampling during
baseflow or during flood event condition) shall be specified.
*primary streams are the largest streams in the city.

Nutrient retention measures would commonly be captured by nitrogen, but may
alternatively use sediment levels or phosphorous as appropriate.
Measures of solid waste particles, such as plastics, may alternately be considered as
appropriate.