High Quality Content by WIKIPEDIA articles! Floods in Saint Petersburg refer to a rise of water on the territory of St. Petersburg, a major city in Russia and its former capital. They are usually caused by the overflow of the delta of Neva River and surging water in the eastern part of Neva Bay but sometimes caused by melting snow. Floods are registered when the water rises above 160 cm with respect to a gauge at the Saint Petersburg Mining Institute. More than 300 floods have occurred since the city was founded in 1703.