Typical values of the annual inflow and outflow of water to the sea, averaged over the period from 1923 to 1985, are as follows: river inflow 38.6 km3, precipitation 15.5 km3, evaporation 34.6 km3, inflow from the Black Sea 36–38 km3, outflow 53–55 km3. Thus, about 17 km3 of fresh water is outflowing from the Azov Sea to the Black Sea. The depth of Azov Sea is decreasing, mostly due to the river-induced deposits. Whereas the past hydrological expeditions recorded depths of up to 16 metres, more recent ones could not find places deeper than 13.5–14 metres. This might explain the variation in the maximum depths among different sources. The water level fluctuates by some 20 cm over the year due to the snow melts in spring.