A control gate is adapted to be installed across a channel for liquids. The control gate has a barrier member capable of vertical or tilting movement and it is either slidingly or pivotally mounted to a frame of the control gate. In one instance, the control gate has at least one side member attached to the barrier member. A drive member co-operates with the side member(s) to allow raising and lowering of the barrier member to regulate flow of liquid through the control gate. The drive member includes a spool and an engagement member that is secured under tension and winds around the spool. As the spool turns it causes, with the engagement member, movement of the barrier member. Also described is a method of measuring flow rate through a control gate.