Ground-water development in East St. Louis area, Illinois. Urbana, IL ...

water levels due to the changes in the stage of the Mississippi
River, and piezometric surface maps under assumed
pumping conditions were prepared. The pumping
center discharge rates that resulted in a piezometric surface
map with the critical water-level elevations in table
33 were assigned to the practical sustained yields of the
pumping centers. The practical sustained yields of the
existing pumping centers are given in table 34.
Table 34.
Practical Sustained Yields of Existing
Major Pumping Centers
Year after
1962 Additional Practical which practical
pumping possible sustained sustained yield
Pumping rate withdrawal yield may be
center (mgd) (mgd) (mgd) exceeded
Alton area 6.3 9.7 16 2000
Wood River area 14.1 5.9 20 1990
Granite City area 9.5 5.5 15 1980
National City area 11.6 6.4 18 2000
Monsanto area 22.6 0.4 23 1965
Total 64.1 27.9 92
Estimates were made of the probable dates when
practical sustained yields of existing pumping centers
may be exceeded. Pumpage totals from 1890 through
1962 in the Alton, Wood River, Granite City, National
City, and Monsanto areas are shown in figures 35 and 36.
The past average rate of pumpage increase in each pumping
center was estimated and extended to intersect the
practical sustained yield of each pumping center. The
assumption was made that the distribution of pumpage
will remain the same as it was in 1962. It is estimated
that the practical sustained yield of the Alton area
pumping center (16 mgd) will be reached after the year
2000; the practical sustained yield of the Wood River
area pumping center (20 mgd) will be reached about
1990; and the practical sustained yield of the Granite
City area pumping center (15 mgd) will be reached
about 1980.
It is estimated that the practical sustained yield of
the National City area pumping center (18 mgd) will
be reached about the year 2000. The rate of pumpage
growth in the National City area may increase markedly,
however, because of the effects of a series of drainage
wells being installed to permanently dewater a cut
along an interstate highway near National City. Pumpage
from the drainage wells was not known at the time
this report was prepared.
Pumpage in the Monsanto area during 1962 (22.6
mgd) is near the estimated practical sustained yield of
23 mgd.
No great accuracy is inferred for the estimated dates
when practical sustained yields may be exceeded in table
34; they are given only to aid future water planning. A
reasonable extrapolation of the pumpage graphs in figures
35 and 36 suggests that total ground-water withdrawals
from wells in existing major pumping centers
will exceed the practical sustained yields by about 2000.
POTENTIAL YIELD OF AQUIFER WITH A SELECTED SCHEME OF DEVELOPMENT
The electric analog computer was used to describe
the effects of a selected scheme of development and to
determine the potential yield of the aquifer under assumed
pumping conditions. The potential yield of the
aquifer is here defined as the maximum amount of water
that can be continuously withdrawn from a selected system
of well fields without creating critical water levels or
exceeding recharge.
The distribution of pumpage with the selected scheme
of development is shown in figure 66. A comparison of
figures 66 and 34 shows that, with the exceptions of three
new pumping centers near the river and one new pumping
center in the Dupo area, the selected scheme of development
is the same as the actual scheme of development
in 1962.
Critical nonpumping water levels for existing and assumed
pumping centers (see table 33) were estimated
from figures 6, 64, and 65 taking into consideration the
effects of dewatering. The electric analog computer was
used to determine pumping center discharge rates that
would cause water levels in all major pumping centers
to decline to the critical stages in table 33. Several values
of discharge in major pumping centers and anticipated
discharge rates for minor pumping centers based on
extrapolations of pumpage graphs for minor pumpage
centers to the year 2015 were assumed and water-level
declines throughout the East St. Louis area were determined.
Model aquifers and mathematical models
(Walton, 1962) based on available geohydrologic data
and information on induced infiltration rates were used
to determine the local effects of withdrawals in pumping
centers near the river. Water-level declines were superposed
on the piezometric surface map for 1900 together
with changes in water levels due to the changes in the
stage of the Mississippi River, and piezometric surface
maps under assumed pumping conditions were prepared.
The total pumping center discharge rate that resulted in
a piezometric surface map with the critical water-level
elevations in table 33 was assigned to the potential yield
of the aquifer with the selected scheme of development.
The potential yield, subdivided by pumping center, is
given in table 35; water-level declines and approximate
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