Seven out of eight largest reservoirs in the Sava River basin are located in the Drina catchment, the largest among them being the Lake Piva on the eponymous river in Montenegro, created after construction of Mratinje Dam.
Groundwater is a very important resource in the Sava River basin, generally used for public water supply of potable water, as a source of water for industrial use, but also as the mainstay of aquatic ecosystems.