A reservoir permit will be required whenever it is proposed to construct a barrier across a stream, channel, or water course, and which will actually retain for a beneficial use a portion of the annual runoff of the stream or water course. (For positive determination of the necessity of a reservoir permit, a reservoir shall be defined as any dam or dike storing water to a depth of ten or more feet at its deepest point, or one that is retaining ten or more acre-feet of water.) This will also apply to a reservoir adjacent to a stream channel when water will be required to fill the reservoir in addition to a constant diversion to keep it full.