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.