hidden Plyussa River, the PLYUSSA, river. Flows in Pskov Oblast and in Slantsi District of Leningrad Oblast. Length: 281 (according to other data, 295) km. Catchment area: 6,500 sq. km. Flow rate: 50 cu. m/s. It flows out of Lake Zaplyusye (Zaimosskoye) and into the Narva... more