Miami-Dade County, FL Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing section
- Code § 24-42.8
- Design storm
- 25-year/10-minute event, zero off-site discharge
- Small-lot pervious setback
- 5 ft on 3 sides minimum
- Small-lot pervious area
- At least 20% of lot
- Enforcing agency
- DERM Director
Summary
Miami-Dade County requires DERM Director approval and onsite stormwater retention before building driveways, patios, pools or other impervious improvements, with strict numeric retention standards for small residential lots.
Stormwater quantity. Lots shall retain, at a minimum, the runoff from a 25-year/10-minute storm event with zero off-site discharge. ... For lots with an area of 5,500 square feet or less: a minimum of 5 feet of pervious area setback on a minimum of 3 sides of the property, with a 6-inch-deep swale along the property perimeter, and a minimum of 20 percent of pervious lot area; or...
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 135).
Full Breakdown
Miami-Dade's Department of Environmental Resources Management (DERM) requires the Director's prior written approval before any non-structural impervious-surface improvement, driveways, patios, additions, is built on a residential lot. Under Code § 24-42.8, single-family and duplex lots must retain the runoff from a 25-year/10-minute storm with zero off-site discharge. For lots of 5,500 square feet or less, that means at least 5 feet of pervious setback on three sides (or 2.5 feet on two sides plus 10 feet on one), a 6-inch perimeter swale, and 20 percent pervious lot area. Section 24-15(7) makes this reach countywide, including the 34 municipalities, unless a city has adopted and gotten DERM sign-off on its own equivalent ordinance.
Violations & Fines
Impervious-surface work started without DERM Director approval voids any building permit issued for it and can be ordered removed; the Director may also require corrective plans and as-built proof if runoff floods an adjoining parcel.
Frequently Asked Questions
Does this apply inside Miami, Hialeah, or other cities?
What triggers DERM review on a small residential lot?
What if runoff from my project floods a neighbor's yard?
Sources & Official References
Other rules in Miami-Dade County
Florida rules heatmap·Compare Miami-Dade County to another location·View the Florida environmental rules overview
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