Pumping tests, chemical and biological analyses of water samples, and well screen inspection by means of a borehole TV camera were conducted in 1969 as part of a study of the efficiency of the relief well system along the Mississippi River between Alton and Gale, Illinois. The purposes of this study are to determine the extent and causes of well deterioration and to investigate methods for improving and maintaining the efficiency of the well system. The relief wells were designed by personnel of the U.S. Army Engineer Waterways Experiment Station and built under the supervision of the U.S. Army Engineering District, St. Louis (SLD). The wells included in this investigation were installed between 1953 and 1955. Since then, SLD has performed a series of well pumping tests, periodically inspected the relief well system, and observed the operation of the wells during high river stages of the Mississippi River. (Author Modified Abstract).