Rough ice 1 mile below Wenrich Slough No flash player has been set up. Please select a player to play Flash videos. Video not playing? Update your browser or download the video clip Karen Brewster asks Sam Demientieff about the cause of rough ice, and Neil Scannell explains rough ice in the river being caused by water coming in from converging sloughs. Process Observed: Rough Ice Date Process Observed: Monday, December 17, 2007 Galleries: Tanana River, 1 mile below Wenrich Slough Gallery