as an example, imagine dredging using a clamshell dredger, which deposits the dredged material on a barge that takes its load to a separate area and dumps it overboard. in this scenario, a dredge plume can be expected to begin at the bottom as the clamshell bucket stirs up loose material. as it rises through the water column to the surface, any material not fully contained by the bucket also creates a plume. at the dumping site, a dredge plume begins at the surface as the material enters the water column from above.