When the board of county commissioners of any county deems it essential to the public interest for flood prevention purposes it may remove drifts, jams, logs, debris, gravel, earth, stone or bars forming obstructions to the stream, or other material from the beds, channels, and banks of watercourses in any manner deemed expedient, including the deposit thereof on bars not forming obstructions to the stream, or on subsidiary or high water channels of such watercourses.