Welf. & Inst. Code, § 7100

(a) The board of supervisors of each county may maintain in the county hospital or in any other hospital situated within or without the county or in any other psychiatric health facility situated within or without the county, suitable facilities and nonhospital or hospital service for the detention, supervision, care, and treatment of persons who have a mental health disorder or a developmental disability, or who are alleged to be such.

(b) The county may contract with public or private hospitals for those facilities and hospital service when they are not suitably available in an institution, psychiatric facility, or establishment maintained or operated by the county.

(c) The facilities and services for persons who have, or are alleged to have, a mental health disorder shall be subject to the approval of the State Department of Health Care Services, and the facilities and services for persons who have, or are alleged to have, a developmental disability shall be subject to the approval of the State Department of Developmental Services. The professional person having charge and control of the hospital or psychiatric health facility shall allow the department whose approval is required to make investigations thereof as it deems necessary at any time.

(d) Nothing in this chapter means that persons who have a mental health disorder or a developmental disability may not be detained, supervised, cared for, or treated, subject to the right of inquiry or investigation by the department, in their own homes, or the homes of their relatives or friends, or in a licensed establishment.