DeKalb County, GA Environmental Rules: Stormwater Management (2026)
Key Facts
- Impervious surface trigger
- 5,000 sq ft or greater
- Land development trigger
- 1 acre or greater
- Runoff trigger
- More than 1 cfs (10-year storm)
- Triggers needed
- One or more
- Applies to
- Unincorporated DeKalb County only
Summary
DeKalb County Code § 14-40(b) pulls a project into stormwater management and water quality review the moment it crosses any one of three thresholds: 5,000 square feet of new impervious surface, 1 acre of land development, or a peak runoff increase of more than 1 cubic foot per second in a ten-year storm.
(b)Applicability criteria for stormwater management and water quality control standards. This article applies to all development which meets one (1) or more of the following criteria:(1)Increases the peak rate of runoff from the site by more than one (1) cubic foot per second for a ten-year frequency storm;(2)Involves the creation or addition of five thousand (5,000) square feet or greater of impervious surface area, or that involves land development activities of one (1) acre of land or greater;
Full Breakdown
Section 14-40(b) states its own reach: the article applies to all development that meets one (1) or more of the listed criteria, so a project needs to trip only a single trigger, not all of them. The first trigger is hydrologic: increasing the peak rate of runoff from the site by more than one (1) cubic foot per second for a ten-year frequency storm. The second is a size test with two prongs: the creation or addition of five thousand (5,000) square feet or greater of impervious surface, meaning hard cover that sheds rain rather than absorbing it, or land development activities of one (1) acre of land or greater.
Because the criteria are alternatives, a compact project that paves 5,000 square feet triggers review even if it disturbs far less than an acre, and a large clearing job of an acre or more triggers review even if it adds no pavement at all. In practice these thresholds catch most subdivisions, commercial sites, and larger home additions in unincorporated DeKalb County, which is the only territory this county provision governs.
Violations & Fines
Development that crosses these thresholds without an approved stormwater management plan is out of compliance with § 14-40 and can be denied permits or held up in review.
Frequently Asked Questions
What triggers DeKalb County's stormwater management rules?
Do I have to hit all three thresholds?
Does this apply inside Decatur or Brookhaven?
Would paving a large area count even without grading an acre?
Sources & Official References
Other rules in DeKalb County
Compare DeKalb County to another location·View the Georgia environmental rules overview
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