There has been granted to the United States a strip of marshland not exceeding one thousand feet in width, lying in and along a tidal stream known as Archer’s Creek, on either side thereof, and extending throughout the entire length of said creek, the exact limits having been determined by the Secretary of War. This grant was made in order to facilitate the improvement of said creek for the purposes of navigation and the United States may dredge, fill in, occupy and use said strip of land in any way that may be necessary to execute any project for such improvement which Congress has adopted since February 21, 1912, or may hereafter adopt and for no other purpose.