IAKE MICHIGAN STUDIES

            Special Report Number IM 12
           CURRENTS -IN THE -SOUTSEBN SASIN
                     June 1963

U. 5. CEPAMMENT F HEALTH, EDUCATION, AHD WELFARE
               Public Health Service
   Division of Water Supply and Pollution Cantrel
      Great Lakes-Illinois Hiver Basins

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                       TABLE OF CONTENTS


INTRODUCTION                                                  1

RESULTS                                                       2

     Daily Current Graphs                                     2
     Rotary Currents                                          3
     Prevalence of Movement                                   3
     Synoptic Maps                                            k

ANALYSIS OF RESULTS                                           6

     Daily Movements                                          6
     Rotary Currents                                          7
     Diffusion or Dispersal                                   8
     Long Term Movements                                      8

SUMMARY OF ALL PHYSICAL STUDIES                               9

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                              TABLES

 1.  Period of the Inertia Circle
 2.  Percent of Speed for Station 17
                             FIGURES

 1.  Current Meter Stations
 2.  Two-Hour Envelopes of Speed and Direction, Station 17, Depth 30 Ft.
 3.    "         "           "           "          "    18,   "     30 "
 h.    "         "           "           "          "    20.   "     50 "
 5.    "         "           "           "          "    20,   "    100 "
 6.    "         "           "           "          "    20,   "    300 "
 7.  Central Vector Diagrams
 8.  Progressive Vector Diagram
 9.  Prevailing Speed and Direction, Station 17, Depth 30 Ft.
10.    "          "          "         "     18,    "   30 "
11.    "          "          "         "     18,    "  100 "
12.    "          "          "         "     20,    "   50 "
13.    "          "          "         "     20,    "  100 "
14.    "          "          "         "     20,    "  300 "
15.    "          "          "         "      k,    "   60 "
16.    "          "          "         "      4,    "   90 "
17.  Current Pattern and Related Wind Flow
18.  Current Pattern and Related Wind Flow

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                          INTRODUCTION
       This is the twelfth and last of a series of special reports
prepared by the Great Lakes-Illinois River Basins Project relating
to the probable effects of returning treated metropolitan wastes
from Chicago to Lake Michigan.  This report presents additional
data pertaining to the movement of waters in the southern basin
of Lake Michigan, and relates the new data to the earlier findings.

       Data from three additional current meter stations, with
records from six current meters, have been evaluated, and compared
with information from the three meters discussed in Special Report
LM 11.  Approximately 38,600 half-hour measurements were recorded
between December and April 1963 from the nine meters.  In addition,
about 15,000 readings made with meters set to record continuously
have been processed.

       The new data are from Stations IT, 18, and 20 located on
a line east of Milwaukee as shown on Figure 1.

       A study of the available data has failed to reveal any
evidence of a well defined current pattern in the southern basin.
It is the purpose of this report, then, to draw such conclusions
as can be properly made concerning the movement and presence or
absence of advective mixing of waters of the southern basin.

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                            RESULTS
Daily Current Graphs

       Figures 2, 3, k, and 5 show the envelopes of maximum and
minimum speeds and directions for each two-hour period during
selected six-day periods.  One period, February 2k to March 2, 1963
was selected for five meter locations to portray the water movement
across the sill area between the southern and northern basins under
an ice cover.

       Figure 2, Station 17, shows a steady southward flow for
nearly 36 hours before the currents shifted to the north for 36
hours.  Current velocities were between 0.1 and 0.2 feet per
second (fps).  During the next two days, the direction changed
more or less continuously, exhibiting rotary currents with
velocities ranging as high as 0.66 fps.  On the last day, the
current again moved southward.  This station was about 3 miles
from shore.

       Station 18 is nearly 22 miles from shore and east of
Station 17.  Figure 3 shows currents at this station, at the
30-ft. depth.  During the period shown, rotary currents persisted
for six consecutive days.  Velocities ranged from nil to more
than 0.2 fps.  It is interesting to note that the speed varies
from near zero to a peak and back again to zero during each
complete revolution.  The average period of rotation is about
18.1 hours, which is approximately the inertia! period, as
described in Special Report No. IM 11.

       Station 20 did not exhibit rotary currents (Figure k),
although the speed shows a cyclic tendency.  Peak speeds up
to 1.45 fps occurred.  The current generally was from a westerly
direction over the six-day period.

       Figure 5, Station 20 at the 100-ft. level, shows that the
rotary type current can occur at greater depths, although very
imperfect as compared to Figure 3  In general, the current was
from the west, shifting to the north and remaining from the north
over most of the period.  Peak velocities reached 1.0 fps.

       Figure 6, Station 20 at the 300-ft. level, shows one peak
velocity of 1.5 fps but speeds were between 0.1 and 0.2 fps most
of the time.  In general, the currents were from the northeast
to northwest sectors.  The tendency toward rotary currents is
shown during the last 2k hours, but the prevailing movement was
definitely from the north.

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Rotary Currents

       Figures 7 and 8 show several classic examples of rotary
currents in Lake Michigan.  Although these currents may occur
during all periods of the year, they are to be expected
principally during calm periods when external forces are at a
minimum.  Figure 7, a set of central vector diagrams, shows
five of the complete circles as measured between k:30 P.M. on
February 25 and 11:00 A.M. on March 1, 1963.  Figure 3 shows
the same data in a different form.  Table 1 shows that the
average period of five rotary current cycles is 18.1 hours.
The theoretical period for an inertial rotation at this
latitude is 17.6 hours.  Figure 8 shows progressive vector
summation diagrams for the same period (February 25 to March 2).
The total theoretical displacement was about 6,600 feet in
106 hours.

Prevalence of Movement

       On Figure 9> data from Station 17 show a bimodal shallow*
water flow near the western shore of the lake.  The distribution
of prevailing direction is 60 percent from the north and kO percent
from the south.  East-west components are small, due to the loca-
tion of the station near the shore.

       Figure 10, Station 18 at the 30-ft. level, shows little
dominance in direction.  About 65$ of the time the direction is
from the south.  Figure 11, data from the same station at 100-ft.
depth, shows a pronounced prevalence of direction from the south,
uitfe less than 10$ from 
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as the total observations recorded.  The average speed for all
observations was 0.25 feet per second and the dominant direction,
340-360, has an average speed of 0.24 fps.  The secondary
sector, l6o-l80, has an average speed twenty percent greater
than the speed in the prevailing northerly direction.  However,
the total flow from the south is still half that from the north.
The speed ranges for the individual sectors agreed well with the
percentage shown for the total observations and the mean speed.
The percentages within a specific speed range exhibited the same
type of curve for the data.  It is believed that these relation-
ships would hold for all stations, i.e., that the prevailing
directions shown on the diagrams are generally indicative of
the predominant movements of water.

Synoptic Maps

       During the time period when data were simultaneously
available from all five current meter stations, several synoptic
plots of the two-hour current velocity envelopes were prepared.
These plots were made twice daily for upper (50 feet) and lower
(100 feet) levels for the times beginning at 0000-0200 hours (CST)
and 1200-1400 hours (CST).  Figure 17 shows a synoptic map for
March 21, 1963.  Stations U, 17, and 18 had data at the 30-ft.
level and at Stations 3 and 20 the data shown are for the 50-ft.
level.  Although some change of direction of flow is likely to
occur between the 30-ft. and 50-ft. levels, records from stations
where both levels were recorded indicate that this change would
not normally be greater than twenty degrees.

       The plotted vector is the two-hour average of speed and
direction.  Figures 17 and 18 are examples of current patterns
believed to be resulting from specific wind flow.

       Figure 17 shows twenty four-hour prevailing winds and a
clockwise current pattern.  Figure 18 shows that the water at the
100-ft. level agrees with the upper layers in direction of movement,
although flow data at this level are available only at Stations 18
and 20.

       The 30-50 ft. chart on Figure 18 shows a variable condition
at Stations 3 and 17 near the shore and opposite to the apparent
clockwise circulation of the center of the basin.

       Additional insight can be gained from the knowledge of
sediment distribution.  Partical size distribution indicates a
flow from the north on the east shore of the lake as far as

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Indiana Harbor.  The offshore formation of dunes (under water)
in the Indiana Harbor area point to the NKE and show a northward
movement of water.  The sediment distribution agrees with the
prevailing flow from the south at Station k.

       Conformal current motion in the southern basin would show
that northwest winds which would pile water on the eastern shore
would produce a movement around the southern part of the basin
and northward along the western shore (l).  This movement
satisfies the continuity conditions.

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                                                               6
                      ANALYSIS OF RESULTS
Daily Movements

       Figures 2 to 6 illustrate the great variability which can
occur from station to station as well as the clarity of current
patterns which can be shown on a two-hour basis.  Figure 17 shows
a period in which the anticyclonic whirl in the southern basin
was strong and extending beyond the limits of the basin.  There is
no evidence of any flow from the north on the west shore.  From
the pattern indicated in Figure 1J it appears that there is no
restriction to movement across the basin sill.  In fact, Figure 18,
the 100 ft. level would indicate that the upper 100 feet of water
moves freely between the two basins during this type of circulation.
Speeds indicate a slow but much larger mass moving southward into
the basin whereas the outflow is a smaller mass but much faster.

       A strong northwesterly wind flow was apparently related to
this current pattern.  This type of anticyclonic flow appears to
occur when similar wind data are available.  No attempt was made to
determine the length of time required to change one current pattern
to a new pattern.

       Figure 18 at the 100-ft. level shows that the deep water
flow moves in the same type of flow as the upper levels.  It
appears that the anticyclonic flow also occurs in the deeper layers
during this period of the year.  Speeds at the 100-ft. level were
about the same as for the upper layers at the same station.

       Figure 18 at the 30-50 ft. level shows an anticyclonic
circulation in the main part of the basin but a complete reversal
along the west shore of the basin.  A light to moderate south-
westerly wind persisted through the day, as well as during the
preceding two days, and may be responsible for the reverse inshore
flow.  This pattern was also repeated at other periods for which
synoptic current and wind observations were available.

       During much of the synoptic study period heavy ice covered
the central and northern portions of the lake.  Late in February it
was estimated that up to 95 percent of the entire lake was ice
covered.  In March there was a sharp break in the cold weather and
temperatures rose to well above normal.  Prevailing westerly winds
and some periods from the southwest helped to clear the southwest
section of the lake early in the month and by the third or fourth
week most of the southern basin was free of solid ice cover.  It

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is noteworthy that current patterns related to wind flow in
February had the same relationships as were found in late March.
It did not appear that the ice cover was important in changing
or shifting the current patterns from the observed wind-current
relationships during the ice-free periods.

       The winter current pattern indicated in Special Report
LM Ho. 11 and related to wind flow has been given further
confirmation by the data from the three additional stations,
as reported herein.

Rotary Currents

       As shown in Figures 3, 7 and 8, rotary currents are a
part of the general lake circulation.  Both Sverdrup and Defant
give illustrations of these occurrences in the oceans (2)(3)-
Although currents of an inertia period were long suspected
it was not until 1936 that they were actually noted in the ocean.
Defant suggests that the rotary currents found by Gustafson and
Kullenberg (2, p. 439) may be related to inertia waves.  During
the period when the rotary currents were found in the lake the
temperature structure was isothermal and the lake had an ice
cover.  Station h} May to July 1962, also indicated the presence
of these rotary currents.  The large eddy mentioned in Special
Report LM No. 11 may also have been the inertia-type rotary
current; however, its period was apparently interrupted by
another pulse or increase in flow.  The period was near 18
hours.  These rotary currents, in themselves, appear to be of
little or no consequence as there is a very small transport
involved.  This very aspect, of no transport, is of considerable-
concern when the question of the movement of pollutants or
other materials are considered.  Present studies show that
although calm conditions may permit a buildup of an effluent,
a rotary current can do likewise.  Both Sverdrup and Defant
stress that this type of inertia current frequently occurs
during the calm after the passage of a storm front.  Thus,
the great amount of energy supplied to the lake can create
inertia-period rotary currents.  Rotary currents do not appear
simultaneously everywhere on the lake.  They more likely will
occur in an area which is not a part of the dominant current
system but rather in an area of temporary calms.  Significantly,
they are more likely to occur on the sheltered side of the lake
during ice-free periods rather than on the upwind side.

       The ice cover over the lake during the winter of 1962-63
provided the exceptional case of observing water movements not

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                                                               8
under the direct influence of the wind.  Although current speeds
are not exceptionally high, there were relatively few calm periods
(less than .03 fps).  Energy supplied probably comes from pressure
exerted on the ice field by the wind, temperature differentials
or stress exerted by variations in atmospheric pressure on the
ice.

Diffusion or Dispersal

       Recent diffusion dye studies on Lake Huron using dye and
drogues pointed up certain aspects that were not found during the
Lake Michigan Drogue Study (see Special Report Wo. LM 10).  The
major phenomenon not found during this period was the "slick."
Slicks or taches d'huile are common to all lakes during moderately
calm weather (4).  Slicks found on Lake Huron showed that an
effluent can be moved with no dispersion.  Similar patterns,
during stratified conditions, can also occur in Lake Michigan.

       Diffusion or dispersal in the longitudinal or vertical axis
varies considerably from day to day or during periods of the year.
In general, dispersal of particles varies considerably, ranging
from no dispersal during periods when slicks occur to great vertical
mixing components during the convective overturn in spring and fall.
Large scale longitudinal mixing probably occurs during severe
weather conditions when strong winds persist.  Present studies by
the Project and other groups, using dye and drogues find, in
general, that mixing during most periods of the year is small.

Long Term Movements

       The daily synoptic flow during the winter reinforces the
previous hypothesis concerning the long term winter movements in
the southern basin.  In general, the circulation was anticyclonic
(clockwise) in the southern basin with a northerly inflow on the
east side of the lake and an outflow on the west side.

       Figures 15 and 16 for May-July 1962 show an apparent
reversal of the winter 1962-63 pattern.  There is reason to
believe that a seasonal shift in pattern would occur with a
gradual shift in the mean wind flow from winter to summer.

       Although certain current patterns appeared to develop
and be maintained during specific wind regimes the wind systems
can and do change.  It would appear that if the wind flows
changed for a sufficient period of time there could be counter-
clockwise patterns in the winter and clockwise patterns in the
summer.

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                SUMMARY OF ALL PHYSICAL STUDIES
       The analysis of nearly 55,000 current observations, mostly
winter data, since May 1962 in the southern basin of Lake Michigan
has given new insight as to the water movements in the basin.

       The data was analyzed by a plot of the two-hour speed and
direction envelopes, plotting of synoptic data, graphs of prevailing
speed and direction and vector diagrams.  The detailed patterns of
water movement in the southern basin are still only partially known but
the influence of the physical factors on the fate of pollutants
are now known in some detail.

       In mid-summer a thermocline develops in the southern basin
and persists until late fall.  Since the thermocline develops
rapidly with the onset of summer it is below the fifty foot level
in a few weeks.  A diffuser site in water depths less than 50 feet
would thus be in the epilinmion water for most of the summer and
fall months.  An effluent which is lighter in density would remain
in or on top of the epilimnion.  Mixing in the epilinmion no matter
how severe, would rarely occur with the lower layers because of the
existence of the thermocline.  During periods of slicks, which
occur in the summer months, any effluent discharged into the upper
layers which is lighter than the surrounding water mass would tend
to concentrate rather than have any tendency toward dispersion.
Drogue studies in the spring of 19^3 show that there is no great
tendency toward dispersion.  In fact, after initial dilution,
great or small, only marked meteorological changes would produce
sudden mixing in the horizontal or vertical components.  Normal
turbulent mixing by the moving water mass would account for the
dilution over a period of time.

       If an effluent were heavier than the upper water mass it
would tend to sink into the hypolimnion with little or no mixing.
However, upwelling could bring this concentrated effluent into
the vicinity of beaches or water intakes.  An effluent which has
an adjusted density such that it would lie on the thermocline
could be brought to the water intakes during periods of upwelling,
by internal waves, or by rotary Kelvin waves.  Summer currents
would usually carry an effluent toward the south but could move
in any direction at random.  In general, only onshore winds
would carry the surface waters directly toward the beaches.  An
offshore wind would produce upwelling and bring bottom waters
to the surface and in the vicinity of beaches or water intakes.

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                                                              10
       During the winter period an effluent which rises or sinks
will not mix any more readily except during high wind conditions.
Water temperatures in mid-winter have decreased Just below
maximum density and thus, no further convective mixing occurs.
Currents found in the winter of 1962-63 indicate a clockwise
rotation moving the water in a general northward direction near
Chicago.

       Vector diagrams indicate that rotary currents, as long as
six consecutive days, will keep a water mass in one general area.
An effluent discharged during such periods would tend to accumulate
heavily in the vicinity of the discharge point.

       The total picture of the influence of the physical factors
on the fate of effluents discharged into the lake would indicate
that a great variety of conditions exist which would tend to
permit concentrated effluents to move to water intakes, beach areas,
or other points of water use, during any period of the year.

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                           REFERENCES

1.  Laevastu, T.  The Causes and Predictions of  Surface  Currents
    in Sea and Lake.  Hawaii Inst. of Geophysics, Report No. 21
    (1962).  p. 5^.

2.  Sverdrup, H.U. et al.  The Oceans.  Prentice-Hall, New York
    (19^6).  p. 1C&9-

3-  Defant, A.  Physical Oceanography, Vol. 1.  Pergamon Press,
    New York (1961).p. 729.

4.  Hutchinson, G.E.  A Treatise on Limnology.  John Wiley and
    Sons, New York (19577^p. 1015.

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Circle No.



   1



   2
                            TABLE 1



                 Period of the Inertia Circle*



                    Start              End
Time
1630
1200
0630
2230
1530

- Degrees
56
37
37
36
42

Time - Degrees
1200 37
0630 37
2230 36
1530 U2
1100 3^
Average Period
Period in Hours
19-5
18.5
16.0
17.0
19.5
18.1
                        Disregarding No. 1 - Average Period   17.6



                        Theoretical Period, ^3 00 N



                                            Latitude - 17.5 hours



*Figure 7

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            TABLE 2



Percent of Speed for Station 17
Speed in
feet per second
0 - 0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Total Observations
Mean Speed
Percent of Total
Observations
25-0
37.0
20.0
4.0
4.0
3.5
2.5
1.5
1.0

--.
5441
.25 fps
Percent of
340-360
15.0
39-5
31.9
4.5
3.2
2.0
0.5
1.0
0.5
0.7

915
.24 fps
Percent of
1600-1800
12.9
33.8
26.3
6.7
4.0
4.3
4.6
3-2
1.6
1.3
l.l
373
.30 fps

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                            25 Miles
     GREAT  LAKES  8  ILLINOIS
      RIVER BASINS  PROJECT
  CURRENT   METER   STATIONS
U.S. DEPT. OF HEALTH, EDUCATION, a WELFARE
        PUBLIC HEALTH SERVICE
 REGION  V            CHICAGO,  ILLINOIS
                         FIGURE  I

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                                    GREAT  LAKES  8  ILLINOIS
                                     RIVER  BASINS  PROJECT
                                       TWO  HOUR  ENVELOPES
                                       OF  SPEED 8 DIRECTION
                                         Station !7,Depth30 Ft.
                               U.S.DEPT. OF HEALTH, EDUCATION, 8> WELFARE

                                       PUBLIC HEALTH SERVICE
                                    REGION  V
                                                       CHICAGO, ILLINOIS
                                                             FIGURE 2

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                                     U.S. DEPT. OF HEALTH, EDUCATION^ WELFARE

                                             PUBLIC HEALTH SERVICE

                                      REGION V            CHICAGO,  ILLiNCIS


                                                                FIGURE  3

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                                        OF SPEED 8  DIRECTION
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                                    U.S.DEPT. OF HEALTH, EDUCATION, ft WELFARE

                                            PUBLIC  HEALTH SERVICE
                                      REGION V
                                                    CHICAGO,  ILLINOIS
                                                              FIGURE 4

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                                         February 24 to March 2, 1963
                                GREAT  LAKES  $  ILLINOIS

                                  RIVER  BASINS  PROJECT
                                   TWO  HOUR  ENVELOPES
                                   OF SPEED 8  DIRECTION
                                     Station 20, Depth300 Ft.
                               U.S. DEPT. OF HEALTH, EDUCATION, S WELFARE

                                       TUBL'C  HEALTH  SERVICE

                                RFGION  J            CHICAGO,  ILLINOIS


                                                          FIGURE 6

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                                      4PM. FEB. 25'
  FEB. 28
 A--
          MAR. 2
A	Speed  is Zero
                                                             FEB. 26
                                         SCALE

                                         1000 ft-
                                      GREAT LAKES  8  ILLINOIS
                                       RIVER  BASINS PROJECT
                                   PROGRESSIVE VECTOR DIAGRAM
                                        TWO HOUR VECTORS
                                     STATION 18-DEPTH 30 FT.
                                  DEPT. OF HEALTH, EDUCATION, Q WELFARE

                                        PUBLIC  HEALTH SERVICE

                                  REGION V           CHICAGO,  ILLINOIS
                                                         FIGURES

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                                                       	Less  thon  1%
   o i
         0 Z
               0.3
             SPEED
                    0 4
615    0.6    0.7
FEET        PER
     (North)
                                           0.8
  0.9
SECOND
                                                        I O
NOTE:
Direction is from the sector shaded,
toward the center.



        CURRENT


December 15,1962 to April 19,1963
                                                                   1.2
              GREAT LAKES  8   ILLINOIS

               RIVER BASINS PROJECT
           PREVAILING  SPEED a DIRECTION

            STATION  17 - DEPTH  30 FT.
                                   U.S. DEPI OF HEALTH, EDUCATION, a WELFARE

                                          PUBLIC HEALTH SERVICE


                                   REGION V            CHICAGO,  ILLINOIS
                                                             FIGURE 9

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                                                     	Less thon 1%
NOTE:
Direction is from the  sector shoded,
toward the center


        CURRENT

DEC.5,1962 TO APR  20,1963
                                180
   GREAT  LAKES  8   ILLINOIS

    RIVER BASINS PROJECT
PREVAILING SPEED 8 DIRECTION

 STATION  18    DEPTH 30 FT
                                  U.S. DEPT. OF HEALTH, EDUCATION, a WELFARE

                                          PUBLIC HEALTH SERVICE

                                  REGION  V            CHICAGO,  ILLINOIS
                                                           FIGURE 10

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                                                     	Less thon 1%
NOTE:
Direction is from  the  sector shoded
toword fhe center.


        CURRENT

DEC 10, 1962 TO APR. 20, 1963
   GREAT LAKES  8  ILLINOIS

    RIVER  BASINS  PROJECT
PREVAILING SPEED 8 DIRECTION

 STATION  18  DEPTH 100 FT
                                 U S DEPT OF HEALTH, EDUCATION, 6 WELFARE

                                         PUBLIC HEALTH SERVICE

                                  REGION  V           CHICAGO, ILLINOIS


                                                           FIGURE II

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                                                     	Less thon l/o
         o 2
              03
             SPEED
 05    OS    O.7
FEET         PER
     (North)
                                           0 8
  0 9
SECOND
NOTE:
Direction is from the sector shotted,
toward the center.


        CURRENT

 DEC.  5, 1962 TO APR. 20, 1963
                                                                  i 2
              GREAT  LAKES  8  ILLINOIS

               RIVER  BASINS  PROJECT
          PREVAILING SPEED 8 DIRECTION

            STATION 20-DEPTH  50 FT.
                                  U.S. DEPT. OF HEALTH, EDUCATION, 8 WELFARE

                                          PUBLIC HEALTH SERVICE

                                  REGION  V            CHICAGO,  ILLINOIS
                                                            FIGURE 12

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                                                               t%
NOTE:
Direction is from the sector shodd,
toword the center.


        CURRENT

December 3, 1962 to April 20,1963
                                180
   GREAT LAKES  8  ILLINOIS

    RIVER BASINS  PROJECT
PREVAILING SPEED 8 DIRECTION

STATION 20- DEPTH 100 FT.
                                  U S DEPT OF HEALTH, EDUCATION, a WELFARE

                                         PUBLIC HCALTH SERVICE

                                  REGION  V           CHICAGO, ILLINOIS
                                                           FIGURE 13

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                                                     	Less  fhon  l/o
NOTE:
Direction is from  the  sector shoded,
toward the center.


        CURRENT

JAN 25, 1963 TO  APR. 20, 1963
                                180
   GREAT LAKES  8  ILLINOIS

    RIVER BASINS  PROJECT
PREVAILING  SPEED 8 DIRECTION

 STATION  20 - DEPTH 300 FT
                                  U S OEPT. OF HEALTH, EDUCATION, a WELFARE

                                         PUBL'C HEALTH SERVICE

                                 ^REGION  V           CHICAGO, ILLINOIS
                                                           FIGURE 14

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                                                     	L  thon  1%
NOTE:
Direction is from  the  sctor  shaded,
toward the center.
        CURRENT

  May 25,1962, to July 26, 1962
   GREAT LAKES  8  ILLINOIS

    RIVER  BASINS  PROJECT
PREVAILING  SPEED 8 DIRECTION

 STATION  4 DEPTH 60 FT.
                                 U.S. DEPT OF HEALTH, EDUCATION, 8 WELFARE

                                         PUBLIC HEALTH SERVICE

                                  REGION  V           CHICAGO, ILLINOIS
                                                           FIGURE 15

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                                                     	Lest thon
NOTE:
Direction is from  the  sector shoded,
toward the center.


        CURRENT

  May 25,1962, to July 26, 1962
   GREAT LAKES  8  ILLINOIS

    RIVER BASINS  PROJECT
PREVAILING  SPEED 8 DIRECTION

  STATION  4 - DEPTH 90 FT.
                                 U.S. DEPI OF HEALTH, EDUCATION, ft WELFARE

                                         PUBLIC HCALTH SERVICE

                                  REGION V           CHICAGO, ILLINOIS
                                                           FIGURE 16

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                                                                        Muskegon
              MARCH 21,1963
             (OOOO-2359CST)
                 MARCH 21,1963
                (OOOO-2359CST)
                                               CURRENT  PATTERN
            WIND FLOW
WIND: Prevailing Direction and Mean Speed in
     Miles Per Hour for 24 Hour Period
CURRENT PATTERN Two Hour Mean Vector
 	Stream Lines Estimated.
 LEVEL:  30ft. and  50ft.
            SCALE
              25
                        50 Mil*
    GREAT  LAKES  8  ILLINOIS
     RIVER  BASINS  PROJECT
    CURRENT  PATTERN  AND
     RELATED  WIND  FLOW
U S DEPT OF HEALTH, EDUCATION, ft WELFARE
       PUBLIC HEALTH SERVICE
REGION V            CHICAGO,  ILLINOIS
                                                                   FIGURE 17

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                                                                    Muskegon
        MAR. 20, 1963
      (0000-2359 CST)
                                                       MAR. 20,1963
                                                     (1200-KOO CST)
                                                       100 FT LEVEL
           JAN 31, 1963
          (0000-2359 CST)
                                                         JAN. 31, 1963
                                                       (0000-020O CST)
                                                   30-50 FT. LEVEL
                                          CURRENT  PATTERN
        WIND  FLOW
WIND' Prevailing Direction and Mean Speed in
     Miles Per Hour for 24 Hour Period
CURRENT PATTERN Two Hour Mean Vector
	Stream Lines Estimated
        SCALE
         25
                    50 Milts
i  i  i  i  i  i
                                         GREAT LAKES  8  ILLINOIS
                                          RIVER BASINS  PROJECT
                                        CURRENT PATTERN AND
                                          RELATED WIND FLOW
                                         U S  DEPT OF HEALTH, EDUCATION, S WELFARE
                                                PUBLIC  HEALTH SERVICE
                                         REGION V            CHICAGO,  ILLINOIS
                                                               FIGURE 18

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