– In 1996, a “pineapple express” weather system delivered 15 inches rain to the Pacific Northwest, and melted the record amount of snowfall the area had just received. The U.S. Army Corps of Engineers worked around the clock to manipulate more than 60 dams in the Columbia River system to minimize flooding. However, unregulated tributaries, such as creeks and rivers without dams, contributed to flooding that resulted in human deaths, mudslides and a landscape that was forever changed. (U.S. Army photo/Billie Johnson)