(also Sereth), a river in Rumania and the USSR (the upper course is in Chernovtsy Oblast, Ukrainian SSR); a left tributary of the Danube. The Siret is 726 km long and drains an area of 44,000 sq km. It flows primarily in a valley that separates the foothills of the Eastern Carpathians from the Moldavian Upland. The main tributaries are the Suceava, Moldova, Bistricła, Trotusul, and Buzău, on the right, and the Bîrlad, on the left. There is high water in spring and a low-water period in summer, interrupted by flash floods. The mean flow rate at the mouth is 185 cu m per sec. The river is frozen from late December through February. The Siret carries a large quantity of sediment, approximately 12 million tons annually. There are hydroelectric power plants in the river’s basin, primarily on the Bistriła; timber is also floated on the river. Below the mouth of the Bîrlad, the Siret is navigable by small vessels. Near the mouth, on the Danube, is the port of Galałi (Rumania).