What types of spillways can carry water around or through a dam?

A spillway is a critical safety feature designed to pass surplus water around or through a dam when a reservoir is full. Depending on the dam type and site conditions, several designs are used to manage this discharge:

• Over-the-dam spillways: For concrete gravity dams, the sloping downstream face often serves as the spillway. High-velocity water may be managed using a "kicker" at the toe to project water away from the foundation or a "ski-jump" design that deflects the jet from a height above the base.12
• Side-channel spillways: Commonly used with earthfill or embankment dams, these are separate structures built to one side of the main dam.12
• Shaft and tunnel spillways: These enclosed structures carry water through the dam or surrounding terrain to a point downstream. Intakes for these may include self-priming siphons or bell-mouthed drop shafts, often called "morning-glory" spillways.12
• Gated openings: Arch dams often feature gated openings within the shell structure, allowing water to discharge in jets that fall clear of the dam’s base.12