Cal. Health & Safety Code § 115800

(a) No operator of a skateboard park shall permit any person to ride a skateboard therein, unless that person is wearing a helmet, elbow pads, and knee pads.

(b) With respect to any facility, owned or operated by a local public agency, that is designed and maintained for the purpose of recreational skateboard use, and that is not supervised on a regular basis, the requirements of subdivision (a) may be satisfied by compliance with the following: (1) Adoption by the local public agency of an ordinance requiring any person riding a skateboard at the facility to wear a helmet, elbow pads, and knee pads. (2) The posting of signs at the facility affording reasonable notice that any person riding a skateboard in the facility must wear a helmet, elbow pads, and knee pads, and that any person failing to do so will be subject to citation under the ordinance required by paragraph (1).

(d) (1) Skateboarding at any facility or park owned or operated by a public entity as a public skateboard park, as provided in paragraph (3), shall be deemed a hazardous recreational activity within the meaning of Section 831.7 of the Government Code if all of the following conditions are met: (A) The person skateboarding is 12 years of age or older. (B) The skateboarding activity that caused the injury was stunt, trick, or luge skateboarding. (C) The skateboard park is on public property that complies with subdivision (a) or (b). (2) In addition to the provisions of subdivision (c) of Section 831.7 of the Government Code, nothing in this section is intended to limit the liability of a public entity with respect to any other duty imposed pursuant to existing law, including the duty to protect against dangerous conditions of public property pursuant to Chapter 2 (commencing with Section 830) of Part 2 of Division 3.6 of Title 1 of the Government Code. However, nothing in this section is intended to abrogate or limit any other legal rights, defenses, or immunities that may otherwise be available at law. (3) (A) Except as provided in subparagraph (B), for public skateboard parks that were constructed on or before January 1, 1998, this subdivision shall apply to hazardous recreational activity injuries incurred on or after January 1, 1998, and before January 1, 2001. For public skateboard parks that are constructed after January 1, 1998, this subdivision shall apply to hazardous recreational activity injuries incurred on or after January 1, 1998. For purposes of this subdivision, any skateboard facility that is a movable facility shall be deemed constructed on the first date it is initially made available for use at any location by the local public agency. (B) For public skateboard parks that were constructed after January 1, 1996, and before January 1, 1998, this subdivision shall apply to hazardous recreational activity injuries incurred on or after January 1, 2012. (4) The appropriate local public agency shall maintain a record of all known or reported injuries incurred by a skateboarder in a public skateboard park or facility. The local public agency shall also maintain a record of all claims, paid and not paid, including any lawsuits and their results, arising from those incidents that were filed against the public agency. Beginning in 2013, copies of the records of claims and lawsuits shall be filed annually, no later than January 30 each year, with the Assembly Committee on Judiciary and the Senate Committee on Judiciary. (5) (A) Except as provided in subparagraph (B), this subdivision shall not apply on or after January 1, 2001, to public skateboard parks that were constructed on or before January 1, 1998, but shall continue to apply to public skateboard parks that are constructed after January 1, 1998. (B) On and after January 1, 2012, this subdivision shall apply to public skateboard parks that were constructed on or after January 1, 1996.