Stream icings are a unique type of river ice that form in a portion of a stream channel which freezes deeply enough to restrict channel flow. Icings are usually found in Arctic and sub- Arctic regions because of the prevalence of permafrost and seasonally frozen ground in these regions. Hydraulic pressure builds up at the point of constriction as the river ice and permafrost thicken during the freeze-up period (Fig 1). Water is forced up through cracks in the river ice and freezes upon exposure to the cold air. This process continues in successive overflows until the source of water is exhausted.