Gov. Code, § 53559

Following the issuance of any refunding bonds pursuant to this article, the legislative body of the local agency shall provide for the payment of principal and interest thereon in the same manner and at the same times as it provides for payment of principal and interest on bonds issued pursuant to its principal act and which constitute general obligations of such local agency. The legislative body may provide in the resolution of issuance of such refunding bonds for the pledge of revenues of any revenue-producing facility of the local agency as additional security for the refunding bonds to the same extent that such revenues were pledged as additional security for the bonds to be refunded.