The ice underside in freshwater lakes of various sizes has been observed to be appreciably rough as a function of flow oscillations and pressure ridging in large open lakes, and variability in snow depth modifying the conductive heat flux (i.e. freezing rates) of the lake. In the case of an underwater oil pipeline rupture occurring in the winter, consolidated ice cover serves to both retain buoyant oil and mask the location of the oil to clean-up crews. The storage capacity of freshwater ice is a function of the roughness of the ice-water interface, the magnitude and correlation length of which varies dependent on the weather from year to year. This presentation focuses on preliminary investigations in the Straits of Mackinac which indicates that ice bottom variability in a region with considerable oscillatory flow is 0.3 m3 per m2, similar to that of first year sea ice. Additionally, the implication of ice-bottom roughness also extend to studies with the aim to improve the understanding of microwave interactions with freshwater ice (observed with airborne and spaceborne platforms), which holds potential to detect the presence of under-ice oil.