Cal. Harbors and Navigation Code § 6939.15

The board, in and by the ordinance authorizing the issuance of the bonds, shall hypothecate and allocate all of the revenues to be realized from the revenue-producing harbor improvement to be acquired or constructed, improved or extended from the proceeds of the bonds to the payment of both principal and interest. The allocation and hypothecation is irrevocable until all bonds and the accrued interest thereon are paid. The allocation and hypothecation shall be made in each case for the exclusive benefit of the bonds to be issued for the purpose of acquiring, constructing, improving or extending the particular revenue-producing harbor improvement, and as additional security for the payment of the principal and interest of the bonds. But the allocation and hypothecation do not constitute the exclusive source of payment. The bonds constitute general obligations of the district and both principal and interest may be paid from any money or sources of revenue of any kind, including taxes, on hand and available for that purpose.