Colo. Rev. Stat. § 32-7-127
The proceeds of refunding general obligation or revenue bonds shall either be immediately applied to the retirement of the bonds being refunded or be placed in escrow in any state or national bank within the state which is a member of the federal deposit insurance corporation to be applied to the payment of the bonds being refunded upon their presentation therefor; but, to the extent any incidental expenses have been capitalized, such refunding bond proceeds may be used to defray such expenses, and any accrued interest and any premium appertaining to a sale of refunding bonds may be applied to the payment of the interest thereon and the principal thereof, or both interest and principal, or may be deposited in a reserve therefor, as the board may determine. Any such escrow shall not necessarily be limited to proceeds of refunding bonds but may include other moneys available for the escrow's purpose. Any moneys in escrow, pending such use, may be invested or reinvested in securities meeting the investment requirements established in part 6 of article 75 of title 24, C.R.S. Such moneys and investments in escrow, together with any interest to be derived from any such investment, shall be in an amount at all times sufficient as to principal, interest, any prior redemption premium due, and any charges of the escrow agent payable therefrom to pay the bonds being refunded as they become due at their respective maturities or due at any designated prior redemption date or dates in connection with which the board shall exercise a prior redemption option. Any purchaser of any refunding bond issued under sections 32-7-125 and 32-7-126 and this section shall in no manner be responsible for the application of the proceeds thereof by the service authority or any of its officers, agents, or employees.
C.R.S. § 32-7-127