spillway

Fluctuations in the lake due to floods are controlled by an immense spillway dam built of concrete.

The spillway is so arranged that as the level of the water in the lake rises the discharging capacity increases.

The spillway, too, if enlarged by explosives, would make a nasty hole to build up.

The spillway is a concrete-lined opening cut through a hill of rock near the center of the dam.

Behind was the bubbling, leaping flow of the spillway itself, and Gatun Dam.