The Moskva River (Russian: Москва-река) is a river that flows through the Moscow and Smolensk Oblasts in Russia, and is a tributary of the Oka River. Moskva and Moscow are two different renderings of the same Russian word Москва. The city is named after the river. The origin of the name is unknown, although several theories exist ^[1]. One theory suggests that the source of the name is an ancient Finnic language, in which it means "dark" and "turbid". Alternatively, the name may come from the Finno-Permic Komi language, meaning "cow-river" or from the Finno-Volgaic Mordovian language, meaning "bear-river". Another claim is that the word is changed version of the Mongolian word "mushka," which means tangled or angled in reference to the tangled and angled setup of the Moscow River that much of the city is near by. The length of the river is 503 km. The area of its drainage basin is 17,600 km². Vertical level drop is 155 meters (long-term average). Maximum depth above Moscow city limits - 3 meters, and up to 6 meters below it.  Normally, it freezes in November-December and begins to thaw around late March. In downtown Moscow, river freezes occasionally; in an unusually warm winter of 2006-2007, ice began setting on January, 25. Absolute water level in downtown Moscow is 120.0 meters above sea level (long-term average of summer lows after World War II), historical maximum was set by the 1908 flood - 127.25 meters above sea level. Main tributaries are the Ruza, Istra, Yauza, Pakhra, and Severka rivers. Sources of water are estimated as 61% thaw, 12% rain and 27% subterranean. After completion of Moscow Canal (1932-1937), Moskva River also collects a share of Upper Volga water. This enabled reliable commercial shipping, which was previously interrupted by summer droughts (older dams built in 1785, 1836 and 1878 were not effective). Average discharge, including Volga waters, varies from 38 m³/s near Zvenigorod to 250 m³/s at Oka inlet. Moscow (Москва́), the capital of Russia, is situated on its banks. The river also flows through the towns of Mozhaysk, Zvenigorod, Zhukovsky, Bronnitsy, Voskresensk, and — at the confluence of the Moskva and Oka — Kolomna. In 2007, there are 49 bridges across Moskva River and its canals within Moscow city limits; the first stone bridge was erected in 1692. Within the city, river is 120-200 meters wide, the narrowest point exactly under the Kremlin walls. Drinking water for the city of Moscow is collected from five stations on Moskva River and Upper Volga reservoirs (north and north-west from the city).