The presence on Bistriţa River, in identical climatic conditions, of sectors with well-developed ice formations in the immediate vicinity of river sectors lacking or with weakly developed such formations demonstrates the existence of other factors beside the meteorological and hydrological ones that may influence the evolution of freezing processes and implicitly of ice jams. A special role is held by the hydraulic exchange relations established between the river and the aquifers (Ciaglic, 1965; Ciaglic and Vornicu, 1973), the mentioned phenomena having a characteristic evolution, sometimes manifested through the total lack of ice due to underground input (Gaman, 2014). River alimentation from underground waters takes place in two situations: a) nearby well-developed alluvial fans close to floodplain or terraces; b) in areas where the river suddenly changes direction from flowing along one of the banks to an almost perpendicular position towards the valley, or where it meanders in the floodplain. The sectors of the river with areas of free water are those generating ice crystals and river-bottom ice and finally frazil slush. In the areas where the river loses water through infiltration in the floodplain, ice formations are much stronger according to the volume of water losses, and total freezing can be recorded. Field observations and measurements conducted in the winters of 2011-2012, 2012-2013, regarding the evolution of freeze phenomena, respectively ice jam formation, on Bistriţa River confirm the mentioned theory.