Environmental Rules in Johnston County, NC (2026)
4 rules for unincorporated Johnston County, North Carolina.
Verified from official government sources
Stormwater Management
Every new development in unincorporated Johnston County must attenuate stormwater runoff so post-development peak rates never exceed pre-development rates, per Land Development Code § 14-387. Sites in the Environmentally Sensitive area district or the Middle Creek Watershed must control the one-year through 100-year storm; everywhere else it is the one-year through 25-year storm, unless a small-lot or limited-disturbance exemption applies.
Johnston County Stormwater Quantity Control Rules
Some RestrictionsJohnston County Code § 14-387
(a) Stormwater generated from development shall generally be conveyed in a designed drainage system of natural drainageways, grass swales, storm sewers, culverts, inlets, and channels. Drainage systems shall be designed, constructed, and maintained to encourage natural infiltration, control velocity, control flooding, and extend the time of concentration of stormwater runoff, consistent with ...
Erosion Control
In unincorporated Johnston County, no one may disturb one acre of land, or any acreage that is part of a larger common plan of development, without first filing an erosion and sedimentation control plan under Johnston County Code § 14-686. The Stormwater Manager must approve the plan before grading starts, and violators face civil penalties up to $5,000 per violation.
Erosion Control Permits in Johnston County
Some RestrictionsJohnston County Code § 14-686(a)
(a) Applicability. Except as provided in Section 14-684(b), it is unlawful to conduct any land disturbing activity that will result in the disturbance of land equal to or greater than one acre, or that will result in the land disturbance of less than one acre if part of a larger common plan of development or sale, including without limitation a subdivision, until an erosion and sedimentation ...
Flood Zones
Before any grading, filling, or construction starts in a Special Flood Hazard Area, unincorporated Johnston County requires a Floodplain Development Permit. Special Flood Hazard Areas are the zones on FEMA's July 19, 2022 Flood Insurance Study and DFIRM panels for the county, adopted by reference into the Land Development Code.
Johnston County Floodplain Development Permit
Some RestrictionsJohnston County Code §§ 14-427, 14-428
Sec. 14-427. - Basis for establishing the Special Flood Hazard Areas. The Special Flood Hazard Areas are those identified under the Cooperating Technical State (CTS) agreement between the State of North Carolina and FEMA in its FIS dated July 19, 2022 for Johnston County and associated DFIRM panels, including any digital data developed as part of the FIS, which are adopted by reference and decl...
Flood Elevation Requirements
Johnston County adds a two-foot freeboard cushion above FEMA's base flood elevation to set its Regulatory Flood Protection Elevation. New residential construction and substantial improvements in a mapped Special Flood Hazard Area must have their lowest floor built no lower than that RFPE.
Johnston County Base Flood Elevation Freeboard
Some RestrictionsJohnston County Code §§ 14-425, 14-440(1)
Regulatory Flood Protection Elevation means the "Base Flood Elevation" plus the "Freeboard". In "Special Flood Hazard Areas" where Base Flood Elevations (BFEs) have been determined, this elevation shall be the BFE plus two feet. In "Special Flood Hazard Areas" where no BFE has been established, this elevation shall be at least two feet above the highest adjacent grade. ... New construction and ...
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