A sluice-gate can be called by many other names depending on the region and purpose. It is also known as the spillway, lock gate, water gate, penstock, or head gate. The term spillway is commonly used in the United States while lock gate refers to the gates used in a canal. Water gate is a general term often used to describe any type of water control system. Penstock is used for the gate in a hydroelectric power plant. Head gate is used primarily in agriculture for irrigation purposes. Ultimately, all these synonyms refer to a mechanism used to control the flow of water in channels, canals, or rivers.