In running waters, some slush ice and ground ice may be formed.

Rapids stay mostly unfrozen throughout the winter. But even in them, the water temperature may drop slightly below zero (the water gets supercooled) and then, small ice crystals form so called slush ice. When the weather is really cold, in supercooled water some ice may be developed also on the bottom, on rocks, etc. Slush ice and ground ice reduce the space for unfrozen water.