California Code, Health and Safety Code - HSC § 25395.65

(a) Except as provided in subdivision (c), until the date when the standards and practices established by the Administrator of the United States Environmental Protection Agency pursuant to Section 101(35)(B)(ii) of the federal act (42 U.S.C. Sec. 9601(35)(B)(ii)) are adopted and take effect, “all appropriate inquiries” means:

(b) Except as provided in subdivision (c), on and after the date when the standards and practices established by the Administrator of the United States Environmental Protection Agency pursuant to Section 101(35)(B)(ii) of the federal act (42 U.S.C. Sec. 9601(35)(B)(ii)) are adopted and take effect, “all appropriate inquiries” means compliance with those standards, except that any portion of the inquiry that includes the practice of engineering or the practice of geology shall be carried out in conformance with applicable state statutes.

(c) If the property is used solely for residential use and has four or fewer units at the time of acquisition by a nongovernmental or noncommercial entity, “all appropriate inquiries” means that a site inspection and title search does not reveal a basis for further investigation.