The maximal mineralization 300-500 mg/l. Average sediment in mouth per year is 129 mm. In 1963 average discharge was 197 m3/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.