(a) In this section, "district" means a navigation district organized under Section 52, Article III, or Section 59, Article XVI, Texas Constitution.
(b) In addition to the authorized investments permitted by this subchapter, a port or district may purchase, sell, and invest its funds and funds under its control in negotiable certificates of deposit issued by a bank that has a certificate of deposit rating of at least 1 or the equivalent by a nationally recognized credit rating agency or that is associated with a holding company having a commercial paper rating of at least A-1, P-1, or the equivalent by a nationally recognized credit rating agency.