Abstract: An improved penstock for water-flow control provides the capability of establishing a constant water level within a levee or a dike and is continuously adjustable between a high and a low water level. The penstock has an erosion-resistant flow channel which is embedded and buried in an earthen levee dike or dam which has leakage prevention and seepage prevention protrusions extending around its outer periphery. In the throat of the flow channel is a pivoted, sealed level-control gate which can be adjusted and latched at any position from a horizontally flat position, permitting unrestricted flow through the channel, to a vertical position, blocking off flow through the channel. This pivoting gate is provided with edge seals to prevent the leakage of water. Once adjusted, the gate will maintain a constant water depth within the body of water enclosed by the levee while passing overflow over the gate.