(a) The provisions of sections 22a-342 to 22a-348 , inclusive, shall not affect the provision of section 7-147 authorizing any town, city or borough to establish such lines within its jurisdiction prior to the establishment of lines by the commissioner, provided the commissioner may alter any lines, however established, upon finding such alterations are necessary to effectuate the purpose of said sections 22a-342 to 22a-348 , inclusive, and section 25-69 . If the commissioner has established lines within a municipality, the commissioner shall have exclusive jurisdiction over any encroachments within such lines.
(b) Notwithstanding the provisions of subsection (a) of this section, any town, city or borough may establish such lines at any time to comply with the eligibility provisions of the National Flood Insurance Program (44 CFR Part 59 et seq.).