Studies on water movements and sediments in Southern Lake Michigan : part 1[-3] ... / by John C. Ayers.

CONCLUSIONS. -:'

Local currents in the shallow waters off Chicago appear
to move essentially in downwind directions. This was also true
for the one run of drogues at USPHS Buoy 14 in midlake off
Racine, for the one run near the position of USPHS Buoy 17,
and for two runs off Grand Haven.
Local currents between USPHS Buoys 17 and 18 and at USPHS
Buoy 18 (only one run each) appeared to contain direction components transverse to the wind direction.
Local currents at USPHS Buoy 20 usually were not directed
downwind. It is believed that set-up and other effects of
shore and nearby sloping bottom were in part responsible.
The annual regimen of temperature (density) in the waters
off Chicago indicates that a typical two-layered water column
is not apt to occur there. In the absence of temporary twolayered conditions caused by internal wave activity, surface
and bottom currents off Chicago may be expected to move in
more or less the same directions.
The general tendency for downwind movement of currents
off Chicago, and one case of observed westward current under
onshore wind, are taken to indicate that effluents from the
proposed diffuser would be able to reach the intakes and
beaches of Chicago under onshore winds.
Crude estimates of apparent dilution in the waters off
Chicago indicate that the region is one of poor inherent ability
to dilute introducd~' materialS.
Definite eutrophic change in the nature of bottom sediments

45