The Sviyaga (Russian: Свияга; Tatar: Зөя; Chuvash: Сĕве) is a river in the Ulyanovsk Oblast and Tatarstan, a right tributary of the Volga. It is 375 kilometres (233 mi) long, and its drainage basin covers 16,700 square kilometres (6,400 sq mi). The Sviyaga flows into the Sviyaga Cove of the Kuybyshev Reservoir, west of Kazan. It freezes up in November or December and stays under the ice until April or May. Major tributaries are the Arya, Birlya, Bula, Karla, Kubnya, Sulitsa and Tosha rivers.
|• location||Ulyanovsk Oblast|
|• elevation||100 m (330 ft)|
|53 m (174 ft)|
|Length||375 km (233 mi)|
|Basin size||16,700 km2 (6,400 sq mi)|
|• average||1,590 m3/s (56,000 cu ft/s) (near mouth)|
|Progression||Volga→ Caspian Sea|
The city of Ulyanovsk is along the Sviyaga. In Ulyanovsk, the Sviyaga flows only a few kilometres away from the Volga, but their confluence is about 200 kilometres (120 mi) north of Ulyanovsk.
The castle of Sviyazhsk, which dates to 1551, is on the island in Sviyaga Cove of the Kuybyshev Reservoir.