Abstract: A movable and adjustable dam including a waterwheel for generating power in rivers, creeks, streams and other flowing bodies of water in which the use of a permanent dam would be impractical or undesirable. The preferred dam includes floatable wall members that can be anchored in position in a body of water to form a water channel there between. The wall members can be unanchored when it is desirable to move the dam. The dam also includes a water wheel mounted between the wall members. The water wheel generates power as it is rotated by water flowing through the channel. Further, the preferred dam includes an adjustable floor comprising a combination of interconnected plates mounted between the wall members. The combination of interconnected plates may be raised or lowered to control the level and flow of water in the water channel and to allow the water wheel to generate power in a mode that is most efficient in response to available water quantity and flow.