California Code, Education Code - EDC § 39835

(a) The governing board of any school district may use schoolbuses to transport persons for purposes of community recreation as provided in Chapter 10 (commencing with Section 10900) of Part 7.  The transportation may be provided on any day or days throughout the school year.

(b) Any school district that files forms with the Superintendent of Public Instruction covering the annual report of transportation expense in connection with reimbursement for transportation shall show on the forms the total mileage of schoolbuses used in providing transportation for community recreation purposes.  The Superintendent of Public Instruction, in accordance with regulations adopted by him or her, shall deduct from the allowances to a school district for transportation an amount equal to the depreciation of schoolbuses due to their use in transporting persons for community recreation.