Dorchester County, SC Environmental Rules: Flood Zones (2026)

Chapter 18, readopted in full by Ord. No. C. Code Title 4, Chapters 9, 25, and 27. Section 18-4 pulls in FEMA's July 18, 2017 Flood Insurance Study and its maps by reference, so the county's special flood hazard areas track FEMA's Zones A, AE, AH, AO, A1-30, V, and VE designations directly. Section 18-5 requires a development permit before any development activity begins inside those zones, and § 18-6 backs that up by barring any structure from being "located, extended, converted, or structurally altered" without full compliance.

Inside the floodway specifically, § 18-52(5) tightens the rule further: no encroachment, including fill, new construction, substantial improvements, or additions, is allowed unless a hydrologic and hydraulic analysis certified by an engineer shows the project won't raise flood levels during a base flood, or FEMA has approved a conditional letter of map revision. Manufactured homes are barred from floodways outright except as replacements in an existing manufactured home park. The local floodplain administrator, whose duties are set out at § 18-34, reviews every permit application, confirms other required federal or state permits are in hand (including Clean Water Act Section 404 permits), and must notify the state and FEMA before any watercourse is altered or relocated. Section 18-7 treats every requirement as a floor, not a ceiling: where this chapter and another rule conflict, the more restrictive one controls.