Monitoring Program Objectives
estuary, lake). Different water resource types have different hydraulic character-
istics which affect their ability to dilute and flush pollutants. Another important
factor affecting water resource response is the type of pollutant.
Wediscussthelakeexampletoillustratethegeneraleffectofapollutantonasingle
water resource type. The fate pollutants in other water bodies may be similar on
Monitoring the physical and
a relative scale but important variations are likely to occur in time and space.
chemical
of
Figure 3.1 shows the approximate time and space scales for the fate of different
types ofpollutants in lakes. In the lower left, thermal jets and bacteria are relatively
water becomes more
short-lived problems with minimal spatial impact. Monitoring short-lived pollut-
meaningful when matched
ants (e.g. bacteria ) therefore requires more monitoring stations to characterize
localized conditions and a higher sampling frequency to detect impact compared
with the time and space
to monitoring more persistent pollutants.
scales of the problem.
In contrast, the problems represented in the upper right, such as nutrients, have
slower reactions and are more likely to affect the whole lake for an extended period
1983). Therefore, monitoring the impact of a persistent
(Chapra and
pollutant generally takes longer and stations need not necessarily be close to the
pollutant source. Sampling frequencies may be lower when monitoring
lake problems. Individual level I physical and chemical variables and how to
monitor them are addressed below.
Temperature
Temperature. A lake temperature profile may be used to determine the extent of
thermal stratification. Inflow plumes of uniform density made up of suspended
sediment or other pollutants can be located by monitoring temperature. Careful
chemical analyses, DO, and specific conductance measurements also include
monitoring temperature.
Horizontal Space Scale
10
Figure 3.1 Appropriate time and
10'
10'
space scales for water quality
I
I
I
I
problems. (after
and
1983)
Solids
I
1
Thermal Jets
Horizontal Space Scale (m)
3.15
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