A National Guard CH-47 Chinook helicopter drops several one-ton sandbags on the spill-way of the Clausen Springs Dam near Kathryn, N.D., April 15. The one-ton sandbags are being lowered and positioned into a place on the dam spillway so that they will divert over-flowing water away from an eroding area of the dam, caused by high water levels. The dam spill-way is considered a flood water retarding structure designed to gradually release rain water and spring melt from the dam reservoir. The erosion occurring on the dam spillway is threatening to allow larger volumes of water than intended to over-flow into a creek, which runs through Kathryn, N.D. and into the Sheyenne River.