a river in Krasnoiarsk Krai, RSFSR; a left-bank tributary of the Enisei (before merging with the Malyi Kas, called the Bol’shoi Kas). Length, 464 km; basin area, 11, 200 sq km.

The Kas flows along the eastern edge of the Western Siberian Plain. It is fed by a mixture of sources, with a predominance of snow. The average water discharge 197 km from its mouth is 53 cu m per sec. The high-water period extends from May through June. The Kas freezes over at the beginning of November and thaws out in mid-May. Together with its left-bank tributary, the Malyi Kas, it was part of the Ob’-Enisei waterway, which connected the Kas with the Kef River.