Monroe County, FL Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing section
- Land Development Code § 114-3, Surface Water Management Criteria
- Design storm
- 24-hour duration, 25-year return frequency
- Water quality target
- 95% nitrogen/phosphorus reduction or net improvement
- Enforcing agency
- Planning and Environmental Resources Department
- Appeal path
- Planning Commission under Section 102-185
- Penalty basis
- Assessed under F.S. Chapter 163
Summary
In the unincorporated Florida Keys (Monroe County), Land Development Code § 114-3 requires every stormwater management plan to meet the county's Manual of Stormwater Management Practices, sized to a 24-hour, 25-year storm event and a 95 percent reduction in nitrogen and phosphorus loads before discharge. Single-family and duplex homes follow simplified best-management-practice standards; larger projects need a sealed engineer's plan reviewed by the Planning and Environmental Resources Department before a building permit issues.
(a)Intent. It is the intent of this section to establish guidelines and criteria for the safe management and disposal of stormwater runoff from developed areas that will minimize or eliminate any resultant adverse impacts on the surface water, groundwater, and other natural resources of the county. ... (b)Applicability. ... Single-family and duplex residences are required to observe best management practices (BMP's) as identified in the sections of the current edition of the County's Manual of Stormwater Management Practices clearly labeled as applicable to single-family and duplex residences ... All other applications for a county building permit are subject to all the criteria established in this section, except those identified in subsection (c). ... (k)Enforcement and penalties. ... Direct the Building Official to issue stop-work orders directing the applicant or persons in possession to cease and desist all or any portion of the work that violates the provisions of these regulations until the remedial work is completed. ... Penalties will be assessed pursuant to F.S. Chapter 163.
Full Breakdown
The Planning and Environmental Resources Department administers Section 114-3 for every building permit application in the unincorporated Keys, from Key Largo to Big Pine and Stock Island. New surface water management systems must either demonstrate a net improvement so post-development nitrogen and phosphorus loads are below pre-development levels, or cut both loads by 95 percent, using a design storm of 24-hour duration and a 25-year return frequency. Off-site discharge cannot exceed the historic rate from the site's natural drainage pattern. Single-family and duplex lots follow the best-management-practice sections of the county's Manual of Stormwater Management Practices and the companion Layman's Brochure, both adopted March 2020 and available from the department; larger commercial, multi-family and mixed-use projects must submit a stormwater management plan sealed by a Florida-registered engineer, with maps, calculations and a designated operating entity (an HOA, condo association or the property owner) responsible for upkeep.
The county exempts mosquito-ditch maintenance, minor repaving that does not add impervious area, true emergencies, and utility work in the right-of-way, but nonconforming systems must still be brought into compliance. The Planning Director schedules erosion-and-sediment, dewatering, bury and final inspections during construction, and no certificate of occupancy issues without sign-off. S. Chapter 163. A denied application or a notice of violation can be appealed to the Planning Commission under Section 102-185.
Violations & Fines
Building without an approved stormwater plan, or deviating from one, can draw a stop-work order from the Building Official and a hold on the certificate of occupancy until the system is corrected. Unresolved cases move to the Code Compliance Department for prosecution, with penalties assessed under F.S. Chapter 163; the county may also perform corrective maintenance itself and place a lien on the property to recover its costs.
Frequently Asked Questions
Does my new home in the Keys need a stormwater permit?
What water-quality standard must a stormwater system meet?
What happens if I build without an approved plan?
Who inspects a stormwater system during construction?
Sources & Official References
Other rules in Monroe County
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