The bridge and park commission shall have the power and is authorized, in connection with its work of development and functions as provided in this chapter, to dredge, deepen and widen any adjacent or existing channels, when this may be done consistently with and in aid of normal navigation and harbor development in the area, being authorized to deposit the spoil, and fill in the bottoms contiguous and adjoining the island, or parts thereof, authorized to be filled in and reclaimed, for the purposes of this chapter.