Of comparable impact is flooding, with the highest water levels in spring. In the area of Lvov and Busk towns in Ukraine, a high level of pollution by ammonium-nitrogen is observed. In the Ukrainian part, in the light of hydrochemical indicators, water quality got somewhat worse in 2009 as compared with 2008, which is consistent with a stable trend of deteriorating water quality as a result of the increase in discharges of non-treated and insufficiently treated urban and industrial wastewaters into the Bug. With the exception of Ambukov, located below the confluence of Hutshva River (where water was in quality category 4, class III, i.e. clean water according to the Ukrainian classification), water quality has been in category 3, class 111, i.e. “relatively clean water”. In the river section in Ukraine close to the border with Belarus, the most commonly occurring quality problems in 2008-2009 were phosphorus, nitrates and metals. Belarus reports that water flowing from upstream has an elevated level of dissolved solids.