Cal. Public Resources Code § 5386

(a) Use of a local park by an eligible entity to provide interpretive services to no more than 30 participating park visitors at once shall be considered an allowable public use of the local park, and shall be treated by the local entity in the same manner as general public use of the local park, provided that the local entity does not confer on the eligible entity any benefit not conferred on the general public. (b) Notwithstanding subdivision (a), a local entity may adopt requirements that apply to an eligible entity that meets the requirements of subdivision (a) if the governing body of the local entity adopts a finding, supported by substantial evidence, of one or more of the following: (1) The requirements are necessary to ensure that public access to a local park, or the protection of environmental resources, is not significantly negatively impaired by an eligible entity that meets the requirements of subdivision (a). (2) The requirements will further access to a local park by an eligible entity that meets the requirements of subdivision (a). (3) The requirements are necessary to address the local entity’s liability related to a visit to a local park by an eligible entity that meets the requirements of subdivision (a).