Nera (Danube) basin and it is not navigable. After the filling of the artificial Lake Đerdap, as a result of the Iron Gate I Hydroelectric Power Station which was finished in 1972, the mouth of the river into the Danube was flooded. In order to allow the optimal electricity production, the water level of the Nera at the mouth should not go below , while it must not exceed it if the flooding of the banks is to be avoided. Since the mid-1990s, there are significant problems in fixing the river's level, as the process is costly and complicated. In 2018, representatives
Enns-class river monitor driving one shaft, using steam generated by two Yarrow boilers driving. The engines were rated at and were designed to reach a top speed of . They carried of fuel oil. The main armament of the "Enns"-class river monitors was a pair of /L45 guns in a single turret forward of the conning tower and three /L10 howitzers to the rear, in individual armored cupolas. They also mounted two individual /L50 BAG anti-aircraft guns, and six machine guns. The maximum range of her Škoda L/45 guns was . Her armour consisted of belt and bulkheads thick, deck armour thick, and