Iowa Code § 12A.8
The authorizing documents may pledge or assign the revenue to be received for payment of the bonds or the proceeds of any contract pledged. A pledge or assignment made by the issuer pursuant to this chapter is valid and binding from the time that the pledge or assignment is made, and the revenue pledged and thereafter received by the issuer is immediately subject to the lien of the pledge or assignment without physical delivery or any further act. The lien of the pledge or assignment is valid and binding against all parties having claims of any kind in tort, contract, or otherwise against the issuer irrespective of whether the parties have notice of the lien. The authorizing documents may contain other provisions the issuer deems reasonable and proper for the security of the bond holders.
Iowa Code § 12A.8
2007 Acts, ch 133, § 8; 2008 Acts, ch 1065, § 8