Clayton County, GA Environmental Rules: Stormwater Management (2026)

Article V of Chapter 38, adopted by Ordinance No. 2020-235 on December 1, 2020, governs post-development stormwater management for new development and redevelopment across unincorporated Clayton County. Under § 38-111.3, the Clayton County Water Authority (CCWA), not the county planning office, serves as the administrator, and § 38-111.4 requires every project to follow the design standards, calculations and formulas in the Georgia Stormwater Management Manual (GSMM), Volume 2; if the county's MS4 stormwater discharge permit ever conflicts with this article, the MS4 permit controls.

The applicability threshold in § 38-111.2 is what determines whether a homeowner or builder is even covered: 5,000 square feet or more of new or added impervious surface, or one acre or more of land disturbance, triggers the article, and smaller lots inside a larger subdivision plan that collectively cross that threshold are covered too. Once covered, § 38-114.4 requires the project to retain the first 1.0 inch of rainfall on-site through runoff reduction, or, if that is proven infeasible, to remove at least 80 percent of the average annual total suspended solids load from a 1.2-inch storm. Section 38-114.5 separately requires 24-hour extended detention of the one-year, 24-hour storm to protect stream channels, § 38-114.6 requires the post-development peak discharge rate for the 25-year, 24-hour storm to be held to the pre-development rate, and § 38-114.7 requires the 100-year, 24-hour storm to be controlled so flooding is not made worse downstream.

Violations of an approved stormwater management plan, including a failure to submit as-built drawings or a final BMP landscaping plan, are enforced under § 38-117.1 as violations of the underlying land-disturbance permit (§ 46-53) or building permit (Chapter 18), giving the county the same stop-work and penalty powers it uses for those permits.