FEMA manual covers dam-overtopping protection - Inadequate spillway capacity is a common problem with many dams. Thousands of dams throughout North America have been determined to have inadequate spillway capacity and would be overtopped during the inflow design flood (IDF). Dam failure from overtopping can lead to a potential for loss of life and significant downstream damages. Thus, new design approaches have been developed that may allow for the dam to be safely overtopped. The design and construction of overtopping protection for dams is increasingly being viewed as a viable alternative to larger spillways as developing watersheds or changing hydrology produce higher peak flows. http://1.usa.gov/1luDWvB