Cook Plant preoperational studies 1970 / John C. Ayers ... [et al.].

A. COOK PLANT PREOPERATIONAL STUDIES

A.1 Recording of Local Water Temperatures
A lake-water temperature sensing and recording system at the Cook Plant
site was activated on 11 May 1970. The system consists of a thermistorequipped submarine cable extending into the lake from the water line near the
north edge of the site property; the shore end of the cable connects to a
multipoint recorder.
Two of the five thermistors are located approximately 300 feet from shore;
the remaining three are at about 2,500 feet offshore. The spring, summer and
fall configuration of the thermistors is that they are held by subsurface
floats at water depths of 2 and 4 feet at the 300-foot position, and at depths
of 2, 12, and 17 feet at the 2,500-foot location.
For the winter ice season, it had been intended to remove the sub-surface
floats and allow the thermistors to lay on the bottom. However, adverse
weather prevented this, and the assemblies were left in the summer configuration. During the winter, part of the circuits were broken, as shown by the
recordings of the various points; but part of them continued to function.
However, the location of the surviving sensors is not known.
Daily maximum and minimum temperatures originating from each thermistor
as well as from the water plants at St. Joseph and Benton Harbor, Mich., have
been assembled by Indiana and Michigan personnel. The St. Joseph intake is
at 1,490 feet from shore in 19 feet of depth. Benton Harbor's intake is at
3,375 feet and in 40 feet of depth.
The temperature data so far collected are given in Table 1.

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