Publication Date


Document Type


First Advisor

Booth, Colin J.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geology


Mineral waters--Illinois; Geology--Illinois


The deepest Paleozoic strata in northeastern Illinois, the Mt. Simon Formation, contains mineralized water. The top 100 meters of the Mt. Simon has been a source of potahle water since the late 1800's, being pumped by municipalities and industries. A gradual increase in the total dissolved solids of this water and water pumped from the overlying Cambro-Ordovician Aquifer has been observed since that time. Pumpage from the Cambro-Ordovician has caused a decrease in the piezometric surface exceeding 275 meters. This suggests upconing of the mineralized water in the Mt. Simon, which would lead to an increase in total dissolved solids. Evidence for upconing is provided by chemical analyses of water samples, the increase in the total dissolved solids of water pumped, and a coarse calculation for upconing. A vertical, two-dimensional, finite difference ground- water flow model was constructed to study the flow system and the upconing of the mineralized water with pumping. The partial differential equation describing groundwater flow was altered to retain the density term in order to calculate the density change of the water in each grid cell at the end of time steps. From model simulations it was determined that the natural flow system of the Mt. Simon has a large recharge area in the northwest and a smaller discharge area in the southeast. Flow is very slow in all but the top 50 meters of the Mt. Simon, and leakage through the Eau Claire is significant. In response to pumping from the Mt. Simon, vertical flow in the Mt. Simon is strong and pumping centers dominate the configuration of the equipotentials. Both local and regional upconing are apparent. The isocons are distorted approximately 60 meters upwards so that wells extending into the Mt. Simon fall between the 1000 and 10,000 milligrams-per-liter isocon. The upconing presented in the model would account for a gradual, overall increase in total dissolved solids as a function of time and increased pumpage from the system.


Bibliography: pages [104]-108.


viii, 127 pages




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