Wake County, NC Environmental Rules: Stormwater Management (2026)
Key Facts
- Applies to
- Unincorporated county only
- Method
- Max composite curve number by soil group
- Example cap
- 43-81 for R-30/R-20 districts
- Exempt
- Ag, forestry, mining, small commercial
Summary
Unincorporated Wake County caps post-development runoff using maximum curve numbers by soil type and zoning district, under UDO Article 9's stormwater management standards.
9-11 - Scope. Except as otherwise expressly stated, the stormwater management regulations of this Article apply to all development within unincorporated Wake County outside the extraterritorial jurisdiction and incorporated boundaries of any municipality....9-20 - Maximum Curve Number after Development. Developers must manage residential runoff so that after development the site will not exceed the following curve numbers, in accordance with procedures specified in the United States Department of Agriculture, Natural Resource Conservation Service, Technical Release 55.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Unified Development Ordinance: Supplement 9).
Full Breakdown
Wake County's stormwater management article applies to all development in unincorporated territory outside any municipality's ETJ or corporate limits (§9-11). Under §9-20, developers must design residential sites so post-development runoff doesn't exceed set maximum composite curve numbers, for example, R-30, R-20, R-15, R-10, R-5, Highway, General Business and Office/Institutional districts are capped at 43 to 81 depending on soil group, calculated per USDA NRCS Technical Release 55 methods. Agriculture, forestry, mining, and small commercial disturbances under a half acre are exempt (§9-12-1).
Violations & Fines
Exceeding the approved curve number or building without an approved stormwater plan is a UDO violation; the Planning Director can deny or revoke permits and impose a $100/day civil penalty under §20-14-3.
Frequently Asked Questions
Does Wake County regulate stormwater runoff from new development?
Is stormwater management required inside Raleigh or Cary?
Sources & Official References
Other rules in Wake County
Compare Wake County to another location·View the North Carolina environmental rules overview
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