Cal. Pub. Res. Code § 5815.5

In compiling data for the wetlands inventory required by Section 5814, the agency and the departments shall, as a first priority, rely on existing sources of information and data. If the agency determines that ground surveys are needed to supplement or correct aerial and satellite imagery, the agency and the department shall obtain the permission of any private landowner before entering his or her property to gather information to complete the wetlands inventory.