California Code, Public Resources Code - PRC § 7524

Any person desiring to purchase swamp and overflowed lands shall make an affidavit and file it in the office of the commission, that he is a citizen of the United States, or has filed his intention to become so;  that he is a resident of the State, of lawful age;  that he desires to purchase lands (describing them) under the law providing for the sale of swamp and overflowed lands;  that he does not know of any valid claim to the lands, other than his own;  that he knows the land applied for and the exterior bounds thereof, and knows, of his own knowledge, that there are no settlers thereon;  or, if there are, that the land has been segregated more than six months by authority of the United States;  and that the land which he now owns (swamp and overflowed), together with that sought to be purchased, does not exceed 640 acres.