I hope Eureka City Council members ask this question before voting on the public nudity ordinance.
Section 5150 is a section of the California Welfare and Institutions Code (WIC) (in particular, the Lanterman–Petris–Short Act or "LPS") which authorizes a qualified officer or clinician to involuntarily confine a person suspected to have a mental disorder that makes him or her a danger to him- or herself, a danger to others, and/or gravely disabled. A qualified officer, which includes any California peace officer, as well as any specifically designated county clinician, can request the confinement after signing a written declaration. When used as a term, 5150(pronounced "fifty-one-fifty") can informally refer to the person being confined or to the declaration itself, or (colloquially) as a verb, as in "I have a possible 5150 here" or "(Someone) was 5150ed".
More details and criteria at above link.
PC 647.6 is annoying/molesting a child.
647.6. (a) (1) Every person who annoys or molests any child under 18 years of age shall be punished by a fine not exceeding five thousand dollars ($5,000), by imprisonment in a county jail not exceeding one year, or by both the fine and imprisonment. (2) Every person who, motivated by an unnatural or abnormal sexual interest in children, engages in conduct with an adult whom he or she believes to be a child under 18 years of age, which conduct, if directed toward a child under 18 years of age, would be a violation of this section, shall be punished by a fine not exceeding five thousand dollars ($5,000), by imprisonment in a county jail for up to one year, or by both that fine and imprisonment. (b) Every person who violates this section after having entered, without consent, an inhabited dwelling house, or trailer coach as defined in Section 635 of the Vehicle Code, or the inhabited portion of any other building, shall be punished by imprisonment in the state prison, or in a county jail not exceeding one year, and by a fine not exceeding five thousand dollars ($5,000). (c) (1) Every person who violates this section shall be punished upon the second and each subsequent conviction by imprisonment in the state prison. (2) Every person who violates this section after a previous felony conviction under Section 261, 264.1, 269, 285, 286, 288a, 288.5, or 289, any of which involved a minor under 16 years of age, or a previous felony conviction under this section, a conviction under Section 288, or a felony conviction under Section 311.4 involving a minor under 14 years of age shall be punished by imprisonment in the state prison for two, four, or six years. (d) (1) In any case in which a person is convicted of violating this section and probation is granted, the court shall require counseling as a condition of probation, unless the court makes a written statement in the court record, that counseling would be inappropriate or ineffective. (2) In any case in which a person is convicted of violating this section, and as a condition of probation, the court prohibits the defendant from having contact with the victim, the court order prohibiting contact shall not be modified except upon the request of the victim and a finding by the court that the modification is in the best interest of the victim. As used in this paragraph, "contact with the victim" includes all physical contact, being in the presence of the victim, communication by any means, any communication by a third party acting on behalf of the defendant, and any gifts. (e) Nothing in this section prohibits prosecution under any other provision of law.