An extensive piezometric survey has been carried out in the southern part of the Po sedimentary basin (in Northern Italy) since 1976. Periodic measurements on a network of 400 deep wells drilled in confined or semiconfined aquifers have been utilized. The 17-year data set has been statistically processed and a band pass algorithm has been applied in order both to detect possible multiyear periodicities and to remove long term linear trends and relatively rapid fluctuations induced by meteorological and tidal effects or anthropogenic exploitation. Regional piezometric fluctuations, characterized by multiannual fluctuations with maximum excursions of 50 to 100 cm, have been identified. A slow-moving crustal deformation front propagating inside a rheologically stratified lithosphere could explain these fluctuations. ¿ American Geophysical Union 1994