The board of supervisors of any county in which the district is situated may direct the harbor commission, appointed pursuant to Section 5902 of this part, to prepare surveys for the improvement, development or protection of any harbor or harbors within the district, prepare plans therefor and estimates of cost thereof, and to report to the board of supervisors thereon, with its recommendations covering the necessity, advantages and benefits to be derived by the improvement, development or protection of such harbor or harbors.