The Malagarasi River is a river in western Tanzania, flowing through Kigoma Region, although one of its tributaries comes from southeastern Burundi. The river also forms the western border of Tabora Region, the southern border of Kagera Region and the southwestern border of Geita Region. It is the second-longest river in Tanzania behind the Rufiji—Great Ruaha, and has the largest watershed of any river flowing into Lake Tanganyika. The Malagarasi-Muyovozi Wetlands are a designated a Ramsar site. Local tribes have nicknamed the Malagarasi as "the river of bad spirits". Geography The Malagarasi is the second-longest river in Tanzania, at . The source of the river is near the Tanzania-Burundi border. The first of the river form the international boundary between Tanzania and Burundi. Several tributaries from the Burundi highlands join its right bank. After the confluence with the Lumpungu River, the Malagarasi enters Tanzania, makes a circle and empties into the eastern side of Lake Tanganyika about south of Kigoma, near Ilagala. It is one of the lake's primary inflows. Moyowosi River is the principal tributary, along with its affluent the Nikongo River; other tributaries include Ugalla River, Gombe River, Ruchugi River, Lumpungu River, and Nguya River. It is characterized as a low stream river, and its drainage includes four biotopes: swampy areas, river channels, a flowing river with a few moderate rapids, and a large double-branched delta. The flow of the river ranges dramatically between the annual cycle of wet and dry seasons, and at times may be susceptible to flooding or reduced to a small stream; flow is also affected by local agriculture and deforestation which increase the level of sediments within the river. At Mberagule, the flow of the river has been gauged to be 6.9 cubic kilometers per year. About from the mouth, the river flows through the Moyowosi swamplands, an area of "extensive swamps and floodplains" and a "marshy labyrinth". It passes through the Dodoma Belt, a geological area of Archaean and Proterozoic age Precambrian crystalline rocks. Watershed With a basin area of , the Malagarasi has the largest watershed of all of the rivers flowing into Lake Tanganyika. The Malagarasi watershed constitutes 30% of the Lake Tanganyika's total watershed area. The Malagarasi watershed is bounded on the north by the watershed of Lake Victoria, on the east by the closed basin of the Southern Eastern Rift, to the south by the closed basin of