The Ilim (Russian: Илим) is a river in Irkutsk Oblast in Russia, a right tributary of the Angara. It flows north between and parallel to the rivers Angara and Lena, and then swings west to join the Angara 40 kilometres south of Ust-Ilimsk.
The Ust-Ilimsk Dam on the Angara (downstream from the older, bigger, and better known Bratsk Dam), completed in the mid-1970s, not only backs up the Angara, but also the Ilim as far as Zheleznogorsk-Ilimsky. The site of the old town of Ilimsk was flooded by the reservoir.
The Ilim is 589 kilometres long, and its basin covers 30,300 square kilometres. The river freezes up in late October and stays icebound until early May. Its main tributaries are the Kochenga, Tuba and the Chora.
