Any harbor improvement district organized and existing pursuant to this part may purchase, lease or obtain by gift lands for public beaches located within the boundaries of the district and may hold, improve or maintain such lands. Any and all such acquisition, improvement or maintenance as is authorized herein shall be accomplished and carried out in accordance with the procedure and in the manner hereinafter provided in this chapter, except that nothing in this chapter shall affect state-owned tidelands and submerged lands or the jurisdiction of the State Lands Commission over tidelands and submerged lands.