When the liquefaction potential of a mapped stratigraphic unit is statistically averaged and assessed spatially, uncertainties associated with groundwater levels are pervasive, due to natural variability in the landscape models, the variations in groundwater depth over time and space, measurement errors, and term vagueness in boring logs. Instead of assessing liquefaction potential assuming an unchanging groundwater level, this study sought to predict and contour the threshold depth-to- groundwater to trigger severe liquefaction in the St. Louis for an assumed M7.5 earthquake emanating from the New Madrid Seismic Zone. The simplified SPT-based procedure and scenario PGA of 0.20g were applied to evaluate the groundwater depth that would exceed a Liquefaction Potential Index of 15. This study revealed that alluvium lying with deeper bedrock surfaces and deeper threshold water depths were both more prone to liquefaction than loess/till deposits, because of their greater thickness and tendency to remain saturated, year-round.