Water on Tap: Design Considerations for Outlet Controls

Outlet works provide for the controlled release of water from reservoirs and may consist of channels, canals, or conduits. Outlet controls typically consist of gates or valves that control the rate of flow through the outlet works. The controls allow the owner/operator to regulate flow in order to accommodate downstream water needs, control reservoir pool levels or drawdown the reservoir at a controlled rate. Failure or improper operation of the outlet controls may induce failure of not only the outlet structure, but of the dam itself due to increased pressures through embankments or overtopping. Appropriate design and maintenance of outlet controls are important to ensure long-term operability and support dam safety.