Mobile, AL Environmental Rules: Stormwater Management (2026)
Key Facts
- Runoff standard
- Post-development ≤ pre-development rate
- Design storm cap
- 10-year peak runoff
- Plan certifier
- State-licensed engineer
- Maintenance duty
- Owner/developer, post-construction
Summary
Mobile requires site development plans to hold post-construction stormwater runoff to pre-development rates, certified by a licensed engineer and reviewed by the city engineer.
Plans and supporting documentation shall be certified by a registered professional engineer licensed by the state that: The plans provide for proper drainage of the project according to sound engineering principles; and The post-development runoff rate does not exceed the pre-development runoff rate as established by the city engineer... The plan shall include provisions for a design that will not cause the pre-development peak runoff rate from a ten-year storm to increase.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 67).
Full Breakdown
Sec. 17-7 requires construction, subdivision, and site plans in Mobile to be certified by a state-licensed professional engineer showing that post-development stormwater runoff will not exceed pre-development rates, with the design capped at the pre-development peak runoff from a ten-year storm. Plans must include detention or retention facilities as needed, and stormwater may not be diverted across adjoining property lines without meeting drainage, easement, or retention conditions in Sec. 17-7(i). The city administers this alongside its NPDES MS4 permit program (illicit discharge detection under Sec. 17-11), and post-construction facilities remain the owner's maintenance responsibility under Sec. 17-10.
Violations & Fines
Non-compliant stormwater plans or illicit discharges into the MS4 are misdemeanors under Sec. 17-14, $60 for a first violation, $150 for a second, and the city engineer can require corrective work or withhold permit approval.
Frequently Asked Questions
Can a Mobile development increase stormwater runoff onto neighboring land?
Who maintains stormwater detention ponds after construction in Mobile?
Sources & Official References
Other rules in Mobile
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