a river in the Yamal-Nenets Autonomous Okrug (formerly Yamal-Nenets National Okrug), Tiumen’ Oblast, RSFSR, and partially on the boundary with Krasnoiarsk Krai.

The Taz is 1,401 km long and drains an area of 150,000 sq km. It rises in the Siberian Uvaly and empties into Taz Bay of the Kara Sea in several branches. It flows through swamps over the northeastern part of the Western Siberian Plain. The river valley is broad, and the river meanders greatly and branches into numerous arms. A sandbar is situated at the mouth.

The Taz is fed primarily by snow (54 percent), but groundwaters also account for a significant share (27 percent). High water lasts from late April through September in the upper course and from late May through September in the lower course. The range of fluctuation in the water level is about 6 m in the upper and middle courses and about 3 m in the lower course. Up to 200 km from the mouth there are tidal fluctuations in the water level, which rises as much as 2 m. The mean flow rate 357 km from the mouth is 930 cu m per sec, with a maximum of 6,630 cu m per sec and a minimum of 157 cu m per sec; at the mouth, it is approximately 1,450 cu m per sec. Of the total annual flow, 60 percent occurs in spring, 21 percent in summer and fall, and 19 percent in winter. The highest water level is in June, which accounts for about 40 percent of the annual flow. The Taz freezes in October and opens up in late May or early June.

The main tributaries are the Bol’shaia Shirta and Khudosei, on the right, and the Tol’ka and Chasel’ka, on the left. The river is fished for muksu, peled, whitefish, broad whitefish, least cisco (Coregonus sardinella), various common fishes, and, to a lesser extent, sturgeon (genus Acipenser) and nelma. The lower Taz is navigable.