An authority may establish one or more subaccounts within the infrastructure fund, and may treat each subaccount as separate and distinct. Money in the infrastructure fund may be invested in any instrument permitted by Section 53601 of the Government Code. However, any money in any subaccount which is separately pledged to secure or pay bonds may be invested in, or may be limited to investments in, any instrument permitted by the resolution or indenture providing for the issuance of the bonds. Any investment income earned on the investment of money in an infrastructure fund shall be credited to the infrastructure fund unless, and to the extent that, federal or state law or agreement, pursuant to which moneys were deposited into the fund, requires otherwise. Any income earned on the investment of money in any subaccount shall be credited to the subaccount unless, and to the extent that, the authority establishing the fund determines otherwise.