On the Russian side, the Vuoksi River was classified in 2009 according to the Russian classification system as “conditionally clean” in the upstream part, as “slightly polluted” further downstream in the southern and northern branches, and as “polluted” close to the mouth of northern branch (at 0.8 river-km). The reason for this is improved effectiveness of wastewater treatment in Finland. After 2005, the production of pulp and paper factories increased, and together with it the loading, but not as much proportionally. Nitrogen concentration has not varied significantly, even though it was at a slightly higher level in the 1980s and in the early 1990s.