When winter surrounds the rivers and lakes here in Montana, the scenery is postcard perfect. I actually look forward to a cold snap in weather temperatures dipping below zero and activating a process called "anchor ice". This colorful product is free-floating crystals called "frazil" that form in cold fast moving waters and collecting on river bottoms, not the tops. These natural events turn the rivers and creeks shades of gray, blues and event emerald green.