Bezdna River, Tatarstan

Not to be confused with Bezdna River, Chuvashia.

Bezdna, Biznä River
Mouth	Kuralovo, Spassky District
Basin countries	Tatarstan, Russia
Length	45 km (28 mi)
Mouth elevation	53 m (174 ft)
Avg. discharge	197 m3/s (7,000 cu ft/s)
Basin area	806 km2 (311 sq mi)

The Bezdna (Russian: Бездна) or Biznä (Tatar: Cyrillic Бизнә, Latin Biznä) is a river in Tatarstan, Russian Federation, a left-bank tributary of the Volga River, flowing into the Kuybyshev Reservoir near Kuralovo, Spassky District. It is 45 kilometres (28 mi) long, and its drainage basin covers 806 square kilometres (311 sq mi).

The maximal mineralization is 300-500 mg/l. The average sediment deposition at the river mouth is 129 millimetres (5.1 in) per year. In 1963 the average discharge was 197 cubic metres per second (7,000 cu ft/s). The town of Spassk, the ancestor of modern Bolgar stood on the river prior to 1956. In 1956–57 the Kuybyshev reservoir was created, flooding the town and the lower stream of Bezdna.