General studies : November, 1967 / by John C. Ayers, Joseph C. K. Huang.

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to follow the plume of the St. Joseph River whose flow reaches
4000 cfs on occasion (Cook and Powers 1964), have given the same
result,.
Since we began recording river-mouth temperatures in the
spring of 1966, the greatest observed difference between rivermouth surface water temperature and open-lake surface water
temperature was 200 F. This was observed at the mouth of the
Kalamazoo River at Saugatuck, Michigan, on 1 June 1966. From
what we have been told of the thermal load to be carried by the
plant effluent, we expect its temperature increment of 250 F to
lie on the high side of the range of natural-river to open-lake
surface temperature differences.
In making the following rough estimates of probable length
of the plume of effluent, under "worst" conditions of light wind
in the height of summer, we have assumed that the spread of the
effluent plume will not be greatly different from that of natural
river plumes in summer. We have further assumed that the summer
flow rates of the Grand and St. Joseph Rivers adequately represent
the full-operational plant effluent which-we are told will be
4000 cfs.
It appears to us that the major difference between a natural
river plume discharged through breakwaters and the plume of the
artificial river of effluent from the plant. is that the latter
will probably be discharged near the natural shoreline and, in
its worst condition, will run along shore in shallow water where
only limited amounts of cool diluting water will be available.
The length of the effluent plume should, then, vary from that of