East Siberian Sea runoff into the East Siberian Sea is relatively small at about 250 km/year that makes only 10% of the total runoff in all the Arctic seas of Russia. The largest contribution is from the Kolyma River at 132 km, followed by the Indigirka River at 59 km. Most runoff (90%) occurs in summer; it is concentrated near the coast, owing to the weak river currents, and therefore does not significantly affect the sea hydrology. The water exchange between the neighboring seas is as follows. The annual outflow to the Laptev Sea, Chukchi Sea and Arctic Ocean is 3,240, 6,600 and
East Siberian Sea the ice cover transforms into drifting ice having the thickness of 2–3 m. The southern winter winds shift this ice northwards, making polynyas near the sea centre. There are no icebergs in the sea. Ice melting typically starts around May, first around the delta of the major Kolyma River. In absence of industry, sea water is rather clean. Minor contaminations are found near the Novosibirsk and Wrangel islands (up to 80 µg/L), due to occasional oil spills, and in Chaunskaya Bay due to the local thermal power station and activities at the major port Pevek. Flora and fauna are relatively