Cook Plant preoperational studies, 1969 / John C. Ayers ... [et al.].

(Table 9) to 5,979,000 in the outfall (Table 10.) There was no evidence of heatstimulated recovery in numbers in the early part of the plume; phytoplankton
numbers fell from 5,979,000 cells per liter in the outfall to 3,558,000 at
Station WP-13 in the plume (Table 11).
In the intake water zooplankton (Table 12) averaged 12.45 organisms per
liter but their numbers fell off to 10.48 in the outfall and many dead and broken
organisms were observed in the material from this station. Continued die-off
from passage through the plant is deduced from the further decline of zooplankton
numbers to 2.29 at Station WP-13 in the plume. Not only did total numbers
diminish, but the numbers of each of the dominant organisms declined steadily
through these three stations.
Benthos (Table 13) at Waukegan were so sparse that little can be made of
the results. The difference in numbers from intake to outfall is within the range
of variation of the method. The increased numbers of amphipods at Station WP-13
probably reflects nothing more than enough reduction in outflow current to enable
these weakly-swimming creatures to remain there.
In summary, the biological data show kill-off of both phytoplankton and
zooplankton in passage through the plant. In both types of plankton there appears
to have been continuation of die-off between the outfall and the nearby portion
of the plume. Benthos results show nothing attributable to the presence of the
plant except washing-out due to currents in the intake and outfall.
Micrometeorological Measurements
At Station MCP-15 in Michigan City harbor on 28 June 1969 near, but east of,
MCP-8 in plume water of 21.6~C, we floated a buoyed temperature staff upon which
Yellow Springs Thermistors Model No. 401 were mounted at heights of 4, 8, 16, and
24 inches above the water surface. A fifth thermistor measured the surface water
temperature.

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