anchor ice

Anchor ice, also known as ground ice, is ice that forms below the surface of a body of water, such as a stream or lake, and attaches to the bottom or submerged objects. This type of ice formation is more complex in rivers than in lakes due to water velocity and turbulence.12

In rivers, supercooling can occur, where water temperature drops below freezing. When ice particles, called frazil ice, are introduced, they can nucleate further ice formation. These frazil particles can adhere to the riverbed or submerged objects, building up a layer of anchor ice. This can cause issues at water intakes by blocking them. Anchor ice can form during cold nights and may detach and float away when temperatures rise.2