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

COOK PLANT PREOPERATIONAL STUDIES

Our 1966 surveys of bottom sediments and benthos around the Cook site
showed the bottom to be sampleable, and indicated, everywhere except in a wavewashed belt along the beach, a benthos population of numbers and composition
comparable to other inshore areas of Lake Michigan. The grid of sampling
stations used in the 1966 survey did not adequately define the width of an
inshore belt of benthos scarcity, hereafter called the "sterile zone."
On 25 April 1969 the R/V INLAND SEAS occupied a series of benthos stations
in 15, 25, and 35 feet of depth along east-west lines extending from shore off
the center of the plant site and off positions 1.25, 2.5, and 5 miles to the
north and to the south of the plant site center. The purpose of these stations
was to determine the density of sampling needed to adequately define the width
of the benthos "sterile zone" along the beach. The station locations and the
benthos counts are presented in Figures 23 through 26. The results indicate
quite clearly that a station in 15 feet of water will adequately sample the
"sterile zone." They also show that, except at Station PPP-2, no amphipods were
present at 25 feet, though oligochaetes were present in small numbers at this depth
in most stations. In view of this it has been decided that sampling at 15 and
30 feet of depth (nearly 1/4 and 1/2 mile from shore) on courses perpendicular
to shore, instead of west by compass, will adequately sample the "sterile zone."
This will also allow minimal error from contouring as benthic organisms come
into the picture as water depth increases.
Phytoplankton, zooplankton, and benthos results are given in Tables 14
through 22.
The phytoplankton results show some of the common characteristics of Lake
Michigan spring collections. The dominant species in spring are diatoms. The
populations, in cells per liter, become greater close to shore. The undesirable

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