Gov. Code, § 55813

(a) The authority may provide for the issuance, sale, or exchange of refunding bonds to redeem or retire any bonds issued by the authority upon the terms, at the times and in the manner which it determines.

(b) The proceeds of any bonds issued for the purpose of refunding outstanding bonds may, in the discretion of the authority, be applied to the purchase or retirement at maturity or redemption of outstanding bonds either on their earliest or any subsequent redemption date or upon the purchase or retirement at the maturity thereof and may, pending that application, be placed in escrow to be applied to the purchase or retirement at maturity or redemption on the date as may be determined by the authority.

(c) Pending that use, the escrowed proceeds may be invested and reinvested by the authority or its trustee in obligations of, or guaranteed by, the United States, or in certificates of deposits or time deposits secured by obligations of, or guaranteed by, the United States, maturing at a time or times appropriate to ensure the prompt payment of principal, interest, and redemption premium, if any, of the outstanding bonds to be so refunded. The interest, income, and profits, if any, earned or realized on the investment may also be applied to the payment of the outstanding bonds to be so refunded. After the terms of the escrow have been fully satisfied and carried out, any balance of the proceeds and interest, income, and profits, if any, earned or realized on the investment thereof may be returned to the authority for use by it in any lawful manner.