April showers may bring May flowers, but spring can also bring ice jams to the thawing rivers and streams across the northern United States. An ice jam or ice dam, is a buildup of broken ice in the river system. It can be a problem that causes the water to back up over the top of highway bridges, roads, or into cities. At times, they can cause flooding. Ice jams can be large–backing up water for miles, or small and only back up water in a small area locally. An ice jam can damage bridges with the amount of water pushing on the jam from behind…