This article provides a complete, additional, and alternative method for doing the things authorized by this article and shall be regarded as supplemental and additional to the powers conferred by any other laws. The issuance of bonds and the entering into any credit reimbursement or other agreement under this article does not need to comply with the requirements of any other law applicable to the local agency or the issuance of bonds or the incurring of indebtedness, except that bonds which were subject to investigations, reports, and approval or certification by the Treasurer pursuant to the District Securities Investigation Law of 1965, Chapter 2.5 (commencing with Section 58750) of Division 2 of Title 6, and the Districts Securities Law, Chapter 1 (commencing with Section 20000) of Division 10 of the Water Code prior to the adoption of this article shall continue to be subject to the investigations, reports, and approval or certification.