Iredell County, NC Environmental Rules: Stormwater Management (2026)

Iredell County Code of Ordinances Section 10.12.1 requires the developer or agent to submit a stormwater drainage plan, prepared by a design professional and showing existing topography and natural drainage, along with the preliminary subdivision plat. The plan must meet nine objectives: the drainage system has to be built to the standards in NCDOT's Handbook for the Design of Highway Surface Drainage Structures and is subject to NCDOT review; no surface water may be channeled into sanitary sewers; the subdivider must connect to an existing storm system where feasible; where extension isn't feasible, a surface system must be engineered to protect the development and adjacent properties from water damage; drainage courses need side slopes of at least three feet of horizontal run per one foot of vertical drop and must be sized to prevent flooding; the minimum grade along a drainage course bottom is a one-foot fall per two hundred feet of horizontal distance; downstream streambanks and channels must be protected from accelerated erosion under the North Carolina Sedimentation Pollution Control Act (G.S.

143-34.12, Ch. 113A, Art. 4) and 15A NCAC Chapter 4; any dam or impoundment must comply with the 1967 N.C. Dam Safety Law with proof filed before final plat approval; and special flood hazard areas must have adequate drainage to reduce flood exposure. Section 10.12.1(B) lets the Subdivision Administrator, on the Technical Review Committee's recommendation, require curb and gutter when a subdivision exceeds thirty lots, when steep topography creates a public-benefit need, or when an adjoining subdivision already has curb and gutter. Section 10.12.1(C) restricts curb-and-gutter development to sites where at least half the run-off discharges into an on-site perennial or annual stream (per current USGS topographic maps) and expressly forbids any direct discharge into Lake Norman, Lookout Shoals Lake, or the Catawba River, protecting the county's two reservoirs and the river that feeds them. Higher-density projects in the WS-IV watershed face additional stormwater control structure standards under the following Section 10.13.