The Poprad and Dunajec rivers, with their subbasins shared by Poland and Slovakia, as well as the San76 River, arc smaller transboundary tributaries to the Vistula. Available groundwater resources in the Polish part of the Vistula River Basin District (including not only the Bug River, but also several smaller rivers discharging directly into the Baltic Sea) are estimated at 8,041 xl0‘ m5/day. Natural riverbeds have to be restored due to the effects of the mining and chemical industries, now no longer operating.