Monitoring Program Objectives
may be quite variable, a well-developed monitoring
Although chlorophyll
protocol can achieve acceptable levels of error in estimating a mean growing
season concentration or some other summary statistic. Potential explanatory
variables to monitor include phosphorus, nitrogen, suspended sediment, or
transparency, depending upon the dynamics of the problem and land use. The
entire
zone should be sampled when monitoring lake chlorophyll
1985; Wedepohl et al. 1990) through the use of a tube sampler or by combining
samples from several depths. Monitoring a single station over the deepest point
may be the most desirable and the most efficient. Samples may also be taken near
the water supply intake or at any other point of designated use.
For
reservoirs with complex
more than one station may
be needed. An additional station may be selected to monitor a lake segment that
functions hydrodynamically as an individual basin with regard to mixing and
stratification. For reservoirs with a strong horizontal pollutant gradient, stations
may be located along the main stem or near the confluence of a tributary
and
the main stem. Typically, however, adding a station does not contribute a
significant amount of information beyond that which is obtained from the original
station.
Macropbytes. Nuisance stands of macrophytes in shallow areas of lakes and
Macrophytes
streams can interfere with a water supply intake, impair recreation, and decrease
aesthetic enjoyment. Monitoring macrophyte species and area1 extent should
occur at the same relative time of the growing season at a regular interval (e.g.
every year or every other year).
Several techniques are available for macrophyte monitoring. Visual surveys or
photographs taken in a standardized manner can be used to track the remediation
or the gross extent of a problem. Harvesting, herbicide applications, and
downs should also be tracked for their effect.
Macrophyte mapping procedures can employ survey techniques.
and
Pesacreta(l986) used sonar (fish locator mounted on a boat) to estimate the
sectional area of macrophytes along a transect. Geissler (1988) used
photographs for macrophyte sampling.
Benthic Macroinvertebrates. Monitoring benthic
can iden-
tify a problem or provide data to determine use attainability, assess trends, or
determine impact. Macroinvertebrates are sensitive to natural and human distur-
bances and are an important food for fish.
(1988) and Plafkin et al.
in the
Rapid Bioassessment
Protocols for Use in Streams and Rivers, provide methods for stream
vertebrate monitoring on natural substrates. Methods vary by the type and number
of habitats (either multiple or single) sampled, skill required for field evaluation
data analysis. Riffle or riffle/run habitat surveys
and laboratory identification,
are the most common. Here a kick net
1988; Piafkin et al.
Surber
sampler (Lind
or some other device may be used to dislodge and collect
benthos from an approximated or measured area of the riffle substrate.
Multiple habitat surveys include sampling riffles,
leaf packs, rocks
and logs. Snags (fallen iogs and branches) may also be sampled in sandy streams
1988). Sampling multiple habitats can collect more
and the technique
is potentially more likely to detect subtle impacts, but care must be taken to follow
a standard operating procedure.
3.
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