Martian Global Dust Storms (GDS) can significantly affect the water cycle in the lower atmosphere (0-40 km). We compare the evolution of water vapor abundances, dust opacity and surface temperatures in the Southern Polar Region (SPR) during GDS years of MY25, MY28 and MY34 relative to years without GDS. During all GDS years, the vapor abundances decrease in the lower atmosphere in the SPR following the storm. Our results suggest that this decrease could be the result of vapor moving to higher altitudes and not being available for poleward transport in the lower atmosphere.