A major problem in the Baltic Sea is eutrophication. Since the beginning of the 20th century, the Baltic Sea has changed from an oligotrophic clear-water sea into a highly eutrophic marine environment. According to 2014 HELCOM assessment, nearly the entire Baltic Sea is affected by eutrophication. Most of the water quality problems in the Baltic Sea originate upstream the thousands of waterways in the catchment area. Some 25% of the nutrient loads to the Baltic derive from wastewater and upstream, transboundary sources of pollution.
1. River Luga is located in the southwest of the Leningrad Region of Russia. It is the second largest river discharging into the Gulf of Finland. The estuary and receiving area of Luga River is currently suffering due to active urban and industrial development of port infrastructure and related sectors. The River Luga is the only river in the Russian part of the Baltic Sea where wild salmon naturally reproduce.
2. The Kurgalskiy Nature Reserve, established in 2000, is included in the network of HELCOM Baltic Sea Marine Protected Areas and on the RAMSAR Convention list of protected wetlands of international importance.The Kurgalskiy Reserve is an area of high conservation value for the Eastern Baltic Sea region as it serves as a spawning ground for many commercial fish species. The Kurgalskiy Reserve is furthermore an important breeding area for many species of marine birds and stopover for migrating birds, and it is the key area for the Baltic ringed seal haul-outs in the Gulf of Finland.
3. Curonian Lagoon is another example of the environmental stress in the Baltic region, the largest shallow lagoon of the Baltic Sea. Due to its natural beauty, the lagoon has a high tourism potential, though this potential is hampered due to harmful algal blooming caused by intensive nutrient loading and eutrophication.
4. Nemunas River is the third-largest contributor of total nitrogen and phosphorus to the Baltic from the territory of four countries. Several of the 58 fish species registered in the Curonian Lagoon are affected, among those a number of rare species included on the Lithuanian, Russian and HELCOM Red Lists for protection.