in each of the guides 17 18 as is illustrated in fig7 the pickets are normally lifted into the waterway with their associated pair of frames and the pickets are raised relative to the frames and held in place by a pin or some other means so that the bottom of the picket is level with the bottom of the frame it will be appreciated that by locking the frames together in this manner there is greater resistance on the part of the frames to slewing than in the prior art type dams since in a horizontal direction wider parts of the bags alternate with narrow parts a large bag of material cannot form between the frames and render the dam unstable the pickets are included to prevent the frames both from sliding back and from sinking in the bed of the waterway when the pickets are driven in crossed over pairs as described above there is improved resistance to sinked compared with the use of vertical pickets the resistance offered to vertical sinking and horizontal sliding both put a considerable bending load on the bottom of the picket so it is sometimes advantageous to reinforce the lower portion of it fig8 shows diagrammatically an arrangement of frames across a river bed and it can be seen that the slope of the banks causing the frames to be at different heights can be accommodated by the clamps used to hold the tops of adjacent frames together it will be appreciated that in constructing a dam in accordance with the above described embodiment of the.