Cal. HSC § 78720

After making a determination, based upon a preliminary site assessment that there has been a release of a hazardous substance on, under, or into the land on a site, the department or a county health officer shall order the property owner to secure the site if all of the following conditions apply to that site: (a) The release does not comply with the terms of a current permit or interim status document or regulation of the department. (b) The site poses a public health risk if human contact is made with the hazardous substance or the surrounding contaminated area. (c) There is a likelihood of human or domestic animal contact.