The Yenisei is the great river of central Siberia: it runs about 3,487 km (2,167 mi) north from the confluence of the Great and Little Yenisei at Kyzyl in Tuva, through Khakassia and Krasnoyarsk Krai, to the Yenisei Gulf of the Kara Sea, and measured from the source of its tributary the Selenga in Mongolia the system is about 5,075 km long, the fifth-longest river system in the world. Its basin covers roughly 2.58 million km², takes in Lake Baikal, and makes it the largest river draining into the Arctic Ocean, with an average flow at Igarka of about 18,000–19,500 m³/s depending on the period measured. The river divides the West Siberian Plain from the Central Siberian Plateau, carries Arctic freight between Krasnoyarsk and Dudinka, and powers two of Russia’s largest hydroelectric dams. Above all, its year is set by ice: on the lower river the water is locked under ice from late October until the break-up of late May or early June.
Russian hydrologists describe the Yenisei as a river with mixed feeding in which snow dominates. Snowmelt supplies a little under half of its water, rain 36–38 percent, and groundwater up to 16 percent in the headwaters, falling towards the mouth. That balance explains the calendar below, which follows the river through one year, starting with the moment the ice lets go.
Late May to June: break-up and the spring flood on the lower Yenisei
The flood begins in May, occasionally in April, and it arrives on the middle river slightly earlier than in the mountains upstream. On the lower river, north of the Arctic Circle, the high water comes from mid-May to early June. Because the river flows north, the thaw starts in the south while the ice downstream is still solid, and the moving ice runs into it. Ice jams are a regular feature of the spring ice run, and they push water levels up fast. In the mountain headwaters the annual range of the river level is 5–7 m where the valley widens and 15–16 m in the narrows; on the lower course it reaches 28 m near the mouth of the Kureyka, before falling to about 11.7 m at Ust-Port close to the Yenisei Gulf.
The discharge records show the scale. The gauge at Igarka, operated for decades and summarised by the Global Runoff Data Centre, has measured a peak of about 112,000 m³/s, against a winter minimum of about 3,120 m³/s; Russian sources quote a maximum of 154,000 m³/s at the same station, and estimates near the mouth reach 190,000 m³/s. In other words, the spring river can carry thirty times or more what it carries in late winter.
People downstream plan around it. Dudinka, the port for the Norilsk mining and smelting complex, works almost all year, but for a couple of weeks each spring the high water floods its quays. When the ice starts breaking up at the end of May, the port moves its cranes to special holding areas and waits for the water to drop, an annual routine that sets Dudinka apart among the world’s ports.
Mid-June to October: the Krasnoyarsk–Dudinka navigation season
Once the flood falls, the lower Yenisei becomes a highway. From mid-June to October, Dudinka receives both seagoing ships and river vessels from Krasnoyarsk, about 2,000 km upstream. Fresh food and consumer goods arrive for Dudinka and Norilsk, and the town notices: fruit and vegetable stalls appear on the streets and grocery prices drop. All large cargoes for the region come by water. A scheduled passenger line between Krasnoyarsk and Dudinka still runs in summer, using two cabin motor ships of the Soviet Project 588 class, and is described as the last such cabin-ship line in the former Soviet Union.
The season has always been short and risky. River steamers first reached the Yenisei in 1864, brought from the Netherlands and Britain across the Kara Sea. The steamship Thames overwintered in 1876, was damaged by ice and was wrecked; success came with the Frazer and Express in 1878, and the Dalman reached Yeniseysk in 1881. During construction of the Trans-Siberian Railway, Captain Joseph Wiggins sailed the Orestes in with rails in 1893, but the long, shallow, ice-bound inlets of both the Ob and Yenisei, prone to high winds, cost several ships, and the sea route faded once the railway opened.
Summer is also when the river’s flow can be traced as it grows. The bars below use Russian hydrological figures for mean discharge at points along the main stem. The flow almost triples between Krasnoyarsk and Yeniseysk, where the Angara, the single outlet of Lake Baikal, joins at Strelka; near its mouth the Angara carries about 4,530–4,980 m³/s, more than the Yenisei’s own mean flow at Krasnoyarsk of 2,864 m³/s. The largest single gain, about 7,600 m³/s, comes on the last long reach to Igarka, where the Lower Tunguska and other northern tributaries join.
July and August: summer rain in the Sayan headwaters and the big dams
In the far south the flood behaves differently. The upper Yenisei, rising at about 3,351 m on the Mungaragiyn-Gol in Mongolia and running through Tuva, has a drawn-out spring-and-summer high water, because snow on the Sayan ranges melts in stages and summer rain adds to it. Summer rain floods also occur along most of the river. The Russian description of the Yenisei crossing every climate zone of Siberia is meant literally: camels live along its upper reaches and polar bears near its mouth.
Two dams now hold much of the summer water back. The Sayano-Shushenskaya Dam near Sayanogorsk in Khakassia is a 242 m arch-gravity dam with 6.4 GW of installed capacity, the largest power plant in Russia, producing about 23.5 TWh a year on average and a peak of 29.4 TWh in 2021. On 17 August 2009 a turbine failed catastrophically, flooding the turbine hall and killing 75 people; all but one of the ten units were damaged or destroyed. Further downstream at Divnogorsk, the 124 m Krasnoyarsk Dam, built from 1956 to 1972, supplies about 6,000 MW, mostly to the Krasnoyarsk aluminium smelter. Its reservoir, the “Krasnoyarsk Sea”, is 388 km long, covers 2,000 km² and holds 73.3 km³. Ships pass the dam on an inclined plane opened in 1985, an electric rack railway with a 9,000 mm track gauge.
October: freeze-up begins at the Yenisei Gulf and the Taimyr reindeer move south
The freeze starts where the thaw ended, in the north. Ice begins forming on the lower river at the start of October. The Yenisei is known for intense frazil and anchor ice, crystals that form within the turbulent water column rather than on the surface, and for an autumn ice run as these floes drift north before the river locks up. A solid ice cover forms on the lower course from the end of October, on the middle river in mid-November (at Krasnoyarsk too, before the dam was built), and in the mountain section from late November into December.
Autumn is also when the largest wild reindeer herd in the world reaches the river. The Taimyr herd of tundra reindeer migrates from the Taymyr Peninsula to winter grazing along the Yenisei; it numbered an estimated 800,000–850,000 animals in 2010, after peaking at more than one million. Downstream, the Brekhovsky Islands in the estuary, an internationally important wetland of about 1.4 million hectares, empty of the waterfowl that nested there through the short summer. The fish are year-round residents: the basin holds 55 native species, among them the Siberian sturgeon, taimen, whitefish and grayling, and two endemics, the gudgeon Gobio sibiricus and a grayling, Thymallus nigrescens, confined to Lake Khövsgöl in Mongolia and its tributaries.
November to April: under ice from Igarka to the Kara Sea
Winter is the river’s low season. With the snow frozen in place across the basin, flow drops sharply, though levels fall slowly because ice dams and slush jams back the water up. Thick aufeis, layered ice built up from repeated overflows, forms on some stretches of the channel. In Dudinka the January mean temperature is −26.9 °C, against a July mean of 13.8 °C. Igarka, 163 km north of the Arctic Circle and built on permafrost, was founded in 1929 as a sawmill port for timber floated down the river in summer; by 1965 it was the second-largest timber-exporting port in the Soviet Union, but the mill closed in 2000 and the population fell from 18,820 in 1989 to 4,417 in 2019.
Navigation does not stop entirely in the far north. When the Yenisei is icebound, Dudinka sends and receives ice-class ships on the Northern Sea Route, carrying out Norilsk’s metals and bringing in fuel and raw materials. A railway built in 1937 links the port to Norilsk, and in 1969 a gas pipeline from Messoyakha to Dudinka and Norilsk was laid.
The stretch below Krasnoyarsk that no longer freezes
One part of the Yenisei now skips winter. Because the Krasnoyarsk Dam releases unfrozen water from its reservoir all year round, the river never freezes for 200–300 km downstream of the dam. In Krasnoyarsk, where the January mean temperature is −15.6 °C, that open water meets frigid air and produces winter fog that hangs over the city and the towns below it.
The same reach carries a different legacy. Studies have found radioactive contamination in the river from the plant that produced bomb-grade plutonium at the formerly secret city of Krasnoyarsk-26, now Zheleznogorsk, near Krasnoyarsk. Accidents still happen in the navigation season: on 8 June 2025 a vessel towing two barges ran aground and broke apart in Kazachinsky District, spilling about 30 tonnes of diesel along up to 50 km of shore.
Then, at the end of May, the ice upstream begins to move, Dudinka lifts its cranes again, and the year turns over. For the lake that feeds the Angara and so much of this flow, see the guide to Lake Baikal’s geography; for the sea that receives it, the Kara Sea guide; and for the Yenisei’s western neighbour, which drains the plain on the other bank, read the complete guide to the Ob.