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The Prairie du Chien Group was injected with 2,754,000 gallons (368,200 cubic feet), or 10,430 cubic metres, of municipally treated water at about 100 gallons per minute (13.4 cubic feet per minute), or 6.3 litres per second, for 20 days. The injection-pipe system was deseed to utilize pipe friction rather than a remote-controlled valve in the well to maintain positive pressure and eliminate air entrainment in the injection water and the escape cf dissolved gasses from the water. During the 20-day injection period the temperature of the injection water declined gradually from 15.0° to 11.2°C, and the flow rate decreased from 108 to 90 gallons per minute (6.8 to 5.7 litres per second). Analyses of test data were, in some instances, based upon hydrologic judgement as well as observations. Results of aquifer tests before and after injections indicated that the tran^missivity had decreased 18 percent during the intervening injection periods; however, th

____-1 Introduction _ Purpose of investigation ___ Location and extent of area Previous investigations _______ _ Methods of present investigation _ Well-numbering system __ Acknowledgments _ _ Hydrogeology _______________ _ The groundwater table and groundwater movement ____ _ Recharge ___________________ __ Discharge _______________________ _ _-Temperature ________________________-____ _ Chemical quality ___________________________________ Aquifer characteristics ______________________________ Aquifer tests _________________________________ Laboratory analyses of aquifer materials _______________ Computations of transmissivity by the gradient-river-gain methcd Summary of transmissivity and storage coefficient __________ Analysis and probable effects of groundwater pumping ________ Theoretical maximum yields ________________________ Relationship of transmissivity, well yield, and saturated thickness Well interference _______________________________ Mathematical model of the hydrologic system in part of the area Pumped water derived from streams or lakes _____________ 39 Discussion of analyses ____________________________ 41 Conclusions _______________________________________ References ______________________________________ 44