California Code, Public Resources Code - PRC § 5192

Each board of park commissioners may let or lease any portion of the parks or grounds under its control, not exceeding one acre in extent, to any one person, until the grounds so leased are required for the improvement of such parks, or for public use as a park. The lease shall be unassignable. No portion may be leased to any street or other railroad company for a term exceeding three years.

All money realized from the leases shall be paid into the treasury of the city, or city and county, in which the parks are situated, and added to the funds appropriated or provided for the support of the parks.