Gov. Code, § 25371

Notwithstanding any other provision of law, the board of supervisors of any county or city and county is hereby authorized and empowered to let to any person, firm or corporation, for a term not to exceed 40 years, any real property which belongs to the county or city and county; provided, that the use to which such property will be put, after construction thereon, is consistent with the use or purposes contemplated upon the original acquisition of such property or to which such property has been dedicated. Property leased pursuant to this section may be used for purposes inconsistent with the use or purposes contemplated upon the original acquisition of such property by the county or city and county or to which such property has been dedicated if the property has belonged to the county or city and county for 10 years and such use or purposes have been abandoned.

Any instrument by which such property is let as aforesaid shall require the lessee therein to construct on the demised premises a building or buildings for the use of the county or city and county during the term thereof, shall provide that title to such building shall vest in the county or city and county at the expiration of said term and shall contain such other terms and conditions as the board of supervisors may deem to be in the best interests of the county or city and county. No county or city and county shall enter into any such contract if at the time 60 percent of the total payments which would become due from the county or city and county if all leases, including the contract to be let, entered into under the authority of this section, were to run their full term plus the total amount of county or city and county bonded indebtedness outstanding at said time exceeds the maximum bonded indebtedness of the county or city and county.