Navigation is impeded by ice in winter and by seasonally varying water levels.
Romanian efforts in the 1980s to drain land in the delta for agriculture damaged Europe's largest wetlands, which are now being rehabilitated. During the Kosovo crisis in 1999, NATO air strikes destroyed bridges across the river in Serbia, obstructing river commerce. Listing from Electric Library , a pay service. Sixth Edition Copyright 2000, Columbia University Press. Copyright 2001 Infonautics Corporation .