Water-quality control, monitoring and wastewater treatment in Lithuania 1950 to 1999.

The Lithuanian water-management system developed on the basis of Soviet regulations in 1950-1990. Surface-water quality monitoring started in the 1950s, and the system was improved in the 1960s. Today, 48 rivers are being monitored using up to 70 parameters. Statutory monitoring of discharges started in 1962, wastewater standards were issued in 1957 and 1966, and then revised in 1996. Wastewater-treatment plants were built first in rural areas, in factories since the 1950s, and later in towns. Since 1991, large capacity municipal plants have been constructed with foreign assistance. Water quality has improved in some rivers since 1970, but Lithuania's main river, Nemunas, remains moderately polluted. The lower Nemunas is especially affected by discharges of municipal and industrial wastewater from Sovietsk and Neman (Russia), which account for half of the total loading. Hydrobiological data of 1994-1998 indicated the eutrophication of the Curonian Lagoon, and bacteriological pollution and blue-green algae blooms in the Baltic Sea north of Klaipeda.