Bulgaria's Environment Ministry Warns Of Rising Water Levels In Rivers Bulgaria's Environment Ministry warns of expected rise of water levels in the rivers, reports Dnevnik.bg. Due to expected heavy rains, starting on Tuesday evening in western Bulgaria and moving to eastern Bulgaria on Wednesday, the ministry warns that water levels in the rivers of Danube, Black Sea and western and eastern catchment areas are expected to rise. According to data of the early warning system, the water in the Tundzha river at the town of Elhovo, has already reached almost critical levels and is expected to rise further.