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
Grisa nera Grisa nera Grisa nera is a red Italian wine grape variety that is grown in the Piedmont wine region of northwest Italy where it is used in both winemaking and as a table grape. The grape is most often used as a minor blending component with wines made from Barbera, Neretta Cuneese and Plassa. In the early 21st century, DNA profiling showed that Grisa nera had a parent-offspring relationship with another red Piedmontese wine grape, Avarengo, though it is not yet known which grape is the parent and which is the offspring. However, this strong relationship between two grapes that