Government Code § 25681.1

A county may reclaim public and private lands therein by levees, bulkheads, breakwaters, fills, embankments, basins, drains, canals, excavations, sluices, pipes, watergates, pumping plants and all works and structures useful therefor. This work is a local improvement and a county affair. The costs of reclamation shall be borne solely by the lands reclaimed.

This section shall not be construed as affecting any public district or public entity now or hereafter established and having similar powers.