also referred to as Ada, was created from the right arm of the Sava with the building of two dams near the northern and southern tips of the island in 1967. The lake is long, has an average width of and is deep. It covers and area of and is above sea level, one of the lowest areas of Belgrade. of its shores on both sides have been transformed into a gravel beach. The water regularly reaches during summer. Both dams allow water to flow through tubes and pumps. This way, the main body of the lake is connected to the smaller body of water on the southwest, which is itself separated from the river by the third dam. This mini "buffer" lake called Taložnik ("depository") is used as a purifier for the waters of both Lake Sava and city waterworks, which also use this water. Filtered water is constantly being pumped into the lake while on the northeast, the water is pumped out by electrically powered pumps through another dam into Čukarica Bay. In this way, an artificial flow of water through the lake is created. Because the water is also used for drinking, sanitation and environmental protection of the lake are imperative and the lake is under rigorous environmental protection. Weeds are groomed on the lake's bottom to purify the water by bonding phosphorus, nitrogen and dirt. Use of motorboats is strictly prohibited in the lake and dogs are not allowed on the beach. Wildlife in the lake mostly consists of the fish species which were introduced since the 1950s. The most common fish in the lake are the introduced silver carp and grass carp, but large autochthonous wels catfish, weighting over , can also be found, causing concern among the swimmers so the authorities issued a statement that they are harmless. In March 2019, a long catfish was caught in the lake. Catfish of this size is a rarity and, as required by the law, it was returned in to the lake. Other catfishes of this size were reported by the divers in previous years, but they lay lazily on the bottom of the lake, not swimming to the surface. There are 20 to 25 fish species in the lake, including the autochthonous carp, northern pike, zander, common bream, asp and European perch, and the imported, and highly invasive brown bullhead, Prussian carp and pumpkinseed. There are