The words "sea wall," as used in this chapter, shall be held to include filling behind the sea wall, culverts, sluiceways, flood gates, and any other construction work found necessary for the protection of the water front from storms, caving banks, overflow, and other like dangers.
The terms "roads, streets, avenues, and highways" as herein used shall include all such roads, streets, avenues, and highways as may form any part of any highway extending along such body of water through or across such county, or any other existing or contemplated public road, street, avenue, or highway connected therewith, extending to or along the side of a harbor or to a boat landing or dock, which, in the discretion of the board of supervisors of such county, is in need of the protection provided in this chapter, whether the same is under the jurisdiction of the national government, the state, the county, or of any municipality.