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

Ground Water Development in East St Louis Area, Illinois
by R. J. Schicht
ABSTRACT
The East St. Louis area extends along the valley lowlands of the Mississippi River
in southwestern Illinois and covers about 175 square miles. Large supplies of ground
water chiefly for industrial development are withdrawn from permeable sand and
gravel in unconsolidated valley fill in the area. The valley fill composed of recent alluvium
and glacial valley-train material has an average thickness of 120 feet. The
coefficient of permeability of the valley fill commonly exceeds 2000 gallons per day
per square foot (gpd/sq ft); the coefficient of transmissibility ranges from 50,000 to
300,000 gallons per day per foot (gpd/ft).. The long-term coefficient of storage of the
valley fill is in the water-table range.
Pumpage from wells increased from 2.1 million gallons per day (mgd) in 1900 to
110.0 mgd in 1956 and was 105.0 mgd in 1962. Of the 1962 total pumpage, 91.1 percent
was industrial; 6.4 percent was for public water supplies; 2.3 percent was for domestic
uses; and 0.2 percent was for irrigation. Pumpage is concentrated in five major pumping
centers: the Alton, Wood River, Granite City, National City, and Monsanto areas.
As the result of heavy pumping, water levels declined about 50 feet in the Monsanto
area, 40 feet in the Wood River area, 20 feet in the Alton area, 15 feet in the
National City area, and 10 feet in the Granite City area from 1900 to 1962. From 1957
to 1961 water levels in the Granite City area recovered about 50 feet where pumpage
decreased from 31.6 to 8.0 mgd. Pumping of wells and draining of lowlands have
considerably reduced ground-water discharge to the Mississippi River, but have not
reversed at all places the natural slope of the water table toward that stream. In the
vicinity of some pumping centers, the water table has been lowered below the river
and other streams, and induced infiltration of surface water is occurring.
Recharge directly from precipitation based on flow-net analysis of piezometric maps
varies from 299,000 to 475,000 gallons per day per square mile (gpd/sq mi). Subsurface
flow of water from bluffs bordering the area into the aquifer averages about 329,000
gallons per day per mile (gpd/mi) of bluff. Infiltration rates of the Mississippi River
bed according to the results of aquifer tests range from 344,000 to 37,500 gallons per
day per acre per foot (gpd/acre/ft). Approximately 50 percent of the total pumpage
in 1962 was derived from induced infiltration of surface water.
An electric analog computer consisting of an analog model and excitation-response
apparatus was constructed for the East St. Louis area so that the consequences of
further development of the aquifer could be forecast. The accuracy and reliability
of the analog computer were established by comparing actual water-level data with
piezometric surface maps prepared with the analog computer.
The analog computer was used to estimate the practical sustained yields of existing
pumping centers. Assuming that critical water-levels will occur when pumping
water levels are below tops of screens and/or more than one-half of the aquifer is
dewatered, the practical sustained yields of all existing pumping centers exceed present
withdrawals. Pumpage in the Monsanto area probably will exceed the practical sustained
yield by 1966; the practical sustained yield of other pumping centers probably
will not be reached until after 1980. The analog computer was also used to describe
the effects of a selected scheme of development and to determine the potential yield
of the aquifer under an assumed pumping condition.
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