California Code, Penal Code - PEN § 554.1

(a) If it is not enclosed within a fence and if it is of an area not exceeding one (1) acre and has no lineal dimension exceeding one (1) mile, by posting signs at each corner of the area and at each entrance.

(b) If it is not enclosed within a fence, and if it is of an area exceeding one (1) acre, or contains any lineal dimension exceeding one (1) mile, by posting signs along or near the exterior boundaries of the area at intervals of not more than 600 feet, and also at each corner, and, if such property has a definite entrance or entrances, at each such entrance.

(c) If it is enclosed within a fence and if it is of an area not exceeding one (1) acre, and has no lineal dimension exceeding one (1) mile, by posting signs at each corner of such fence and at each entrance.

(d) If it is enclosed within a fence and if it is of an area exceeding one (1) acre, or has any lineal dimension exceeding one (1) mile, by posting signs on, or along the line of, such fence at intervals of not more than 600 feet, and also at each corner and at each entrance.

(e) If it consists of poles or towers or appurtenant structures for the suspension of wires or other conductors for conveying electricity or telegraphic or telephonic messages or of towers or derricks for the production of oil or gas, by affixing a sign upon one or more sides of such poles, towers, or derricks, but such posting shall render only the pole, tower, derrick, or appurtenant structure posted property.