Dunwoody, GA Environmental Rules: Stormwater Management (2026)
Key Facts
- Trigger threshold
- 5,000 sq ft impervious or 1 acre disturbance
- Runoff reduction standard
- Retain first 1.0 inch of rainfall on site
- Overbank protection storm
- 25-year, 24-hour return frequency
- Design storm capacity
- 100-year storm event
- Facility fencing
- 4 ft minimum if water depth exceeds 4 ft
- Enforcement
- Treated as land disturbance/building permit violation
Summary
Dunwoody requires a stormwater management plan for new development or redevelopment that adds 5,000 square feet or more of impervious surface, or disturbs one acre or more, before any land disturbance or building permit issues. The plan must follow the Georgia Stormwater Management Manual and control runoff quality, channel erosion and flooding.
Sec. 16-91. - Post construction stormwater management for new development and redevelopment.( ... c)Applicability criteria for stormwater management standards. The stormwater management regulations of this division applies to the following activities:(1)New development that involves the creation, addition or replacement of 5,000 square feet or more of new impervious surface area or that involves other land disturbing activities of one acre or more; ... (6)Overbank flooding protection. Downstream overbank flood and property protection must be provided by controlling (attenuating) the post-development peak discharge rate to the predevelopment rate for the 25-year, 24-hour return frequency storm event. ... Sec. 16-98. - Inspections and maintenance.( ... c)Violations and enforcement. Any violation of the approved stormwater management plan during construction, failure to submit as-built drawings, failure to submit a final BMP landscaping plan, or failure of the final inspection shall constitute and be addressed as violations of, or failures to comply with, the underlying land disturbance permit pursuant to section 16-60 or the underlying building permit pursuant to section 16-29.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 49).
Full Breakdown
Chapter 16, Division 5 of the Dunwoody Code of Ordinances governs post-construction stormwater for new development and redevelopment. Section 16-91(c) triggers the requirement at 5,000 square feet or more of new impervious surface, or one acre or more of land disturbance, and also applies to any hotspot commercial or industrial use regardless of size and to linear transportation projects over that threshold. Exempt activities include emergency repairs, utility trenching, and ADA-compliance work under section 16-91(d). 0 inch of rainfall on site, channel protection requires 24-hour extended detention of the one-year, 24-hour storm, and overbank flood protection requires attenuating the post-development peak discharge to the predevelopment rate for the 25-year, 24-hour storm.
Section 16-97(c) separately requires the drainage system to handle a 100-year storm event, and section 16-97(g) requires permanent fencing at least four feet high around any stormwater or sedimentation facility holding more than four feet of water. Before a permit is issued, applicants must complete a pre-submittal meeting, a stormwater concept plan and a full stormwater management plan sealed by a Georgia-licensed professional engineer or landscape architect (section 16-92), pay the review fee set by the city's fee schedule (section 16-93), and sign a recorded inspection and maintenance agreement obligating the owner to inspect, clean and repair the system, with obligations that run with the land to future owners (section 16-96). The community development director administers the program and can require additional information for sites classified as pollutant hotspots.
Violations & Fines
Under section 16-98(c), a violation of the approved stormwater management plan, including failure to submit as-built drawings or pass final inspection, is treated as a violation of the underlying land disturbance permit (section 16-60) or building permit (section 16-29), giving the city the same notices, stop-work orders and penalties available for those permit violations. Under section 16-98(g), an owner's failure to maintain a stormwater facility is enforced as a property maintenance violation under section 8-1, and the public works director may issue 30 days' written notice (24 hours if there is an immediate danger to health or safety) before the city performs the repair itself and liens the property for the cost, collectible on the ad valorem tax bill.
Frequently Asked Questions
What triggers a stormwater management plan in Dunwoody?
Is there a fee to file a stormwater plan?
What happens if I fail to maintain my stormwater facility?
What storm event must my drainage system handle?
Sources & Official References
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