Abstract: An anti-scouring device for preventing scouring of the bed of a flowing stream at an upstream or downstream location proximate a dam has a plurality of rows of concrete members, positioned in the direction of flow of the stream, on the bed of the stream. The concrete members have a base and at least one downwardly extending penetrating member which secures the member to the bed. The concrete members may have downwardly extending legs and upwardly extending retention posts and be linked together in the rows by a flexible linkage. Or, the concrete members may have downwardly extending intersecting webs to serve in securing the members to the bed. Methods for forming the anti-scouring device on the bed are also provided.

Abstract: An immersed dam foundation and a dam structure are formed in a body of moving water by forming a plurality of spaced piers having temporary support posts thereon. A current deflector is secured to the upstream support posts and sheet piling walls are driven to form upstream and downstream walls between the piers forming a base therebetween. The base is covered with a tremie seal and the walls cut off so that a prefabricated dam structure can be floated to a location above the tremie seal and lowered onto anchor points on the adjacent piers and secured to the piers and tremie seal. An exposed face of a pier is protected from the currents by barriers that serve as a portion of the next upstream and downstream walls, with gravel covered by precast concrete pads. The access galleries of adjacent prefabricated dam structures are closely aligned and seals provided therebetween.