Gatehouse (waterworks)

Such devices usually consist of one or more pipes or tunnels through the embankment of the dam, directing water usually under high pressure to the river downstream.

They may also be used when river flows must be bypassed due to maintenance work in the power station or diversion gates.

Although similar in purpose to spillways, outlet works provide a more controlled release to meet downstream flow requirements.

A regulating gate or valve controls water flow into the pipes of the outlet works, which discharge downstream into a stilling basin or directly into the river.

[2] The inlets of the outlet works may consist of either gates or valves, or be composed of a more primitive system of stoplogs.