California Code, Government Code - GOV § 25549.11

(a) After considering all proposals submitted, the board of supervisors shall have the authority to select the plan or proposal which best meets the needs of the county or city and county and to enter into a lease or agreement incorporating that plan or proposal either as submitted or as revised by the board.

(b) The board shall require any person, firm, or corporation with whom it enters into a lease or agreement pursuant to this article to file a bond for the performance of the lease or agreement for the completion of the building to be constructed.