Phytoplankton of the seasonal surveys of 1977, and further pre- vs. post-operational comparisons at Cook Nuclear Plant / John C. Ayers, Susan J. Wiley.

October 1977 is consistent with an autumn silica depletion in the epilimnion.
The record on this diatom indicates some change in the lake, not any effect of
Cook Plant operation.
The percentage compositions of the phytoplankton by five major algal
groups (blue-greens, greens, flagellates, diatoms, and desmids-and-others) at
four inshore stations in front of the plant and at two inshore reference
stations distant from the plant have been compared from July 1970 through
November 1977. In both preoperational and operational years the five community
components have shown many similarities of temporal change in the two station
groups; in the operational years the similarities have, if anything, been
greater than during preoperation. Due to a change in counting technique in
1974, blue-green algae showed an increase in that year which has continued
since. No dissimilarities in community composition attributable to plant
operation have been revealed by this method of analysis.
The numbers of phytoplanktonic forms collected during the seasonal major
surveys have shown generally increasing trends since 1971 in both inner
stations near the plant and outer reference stations in all three depth zones.
The trends toward increasing numbers of forms are attributable to the lake's
eutrophication process, not to Cook Plant operation.
Of the nine major algal categories (separately, not combined to five as
was done for percentage composition of the community) and total algae, only
filamentous blue-greens have shown increases limited to the operational years.
In Zone 0 the increases at the outer stations have equalled or exceeded those
at the inner stations; in Zone 1 the summer increases have been greater at the
outer stations; in Zone 2 summer increases have been greater at the inner
stations in 1976 and 1977. Zone 2 being offshore, the summer increases there
are attributed to summer silica depletion in the epilimnion of the offshore

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