Conn. Gen. Stat. § 8-2l

(b) Whenever a municipality, pursuant to the National Flood Insurance Program, 44 CFR Part 59 et seq., is required to revise its zoning regulations or any other ordinances regulating a proposed building, structure, development or use located in a floodplain, the revision shall provide for restrictions for flood storage and conveyance of water for floodplains that are not tidally influenced as follows:

(1) Within a designated floodplain, encroachments resulting from fill, new construction or substantial improvements, as defined in 44 CFR Part 59.1, involving an increase in footprint to the structure shall be prohibited unless the applicant provides to the zoning commission certification by a state licensed engineer that such encroachment shall not result in any increase in base flood elevation;

(2) The water holding capacity of the floodplain shall not be reduced by any form of development unless such reduction (A) is compensated for by deepening or widening the floodplain, (B) is on-site, or if adjacent property owners grant easements and the municipality in which the development is located authorizes such off-site compensation, (C) is within the same hydraulic reach and a volume not previously used for flood storage, (D) is hydraulically comparable and incrementally equal to the theoretical volume of flood water at each elevation, up to and including the hundred-year flood elevation, which would be displaced by the proposed project, and (E) has an unrestricted hydraulic connection to the same waterway or water body; and

(3) Work within adjacent land subject to flooding, including work to provide compensatory storage, shall not result in any increase in flood stage or velocity.

(c) Notwithstanding the provisions of subsection (b) of this section, a municipality may adopt more stringent restrictions for flood storage and conveyance of water for floodplains that are not tidally influenced.

See Sec. 25-68k re hazard mitigation and floodplain management grant program.