Impervious Surface Ordinance

The Impervious Surface Ordinance enhances resilience, improves water quality, and reduces future risks of flooding in Miami-Dade County.

What is an impervious surface? 

An impervious surface is any surface that does not allow water to pass through it, thereby preventing the natural infiltration of rainwater into the ground. These surfaces include materials such as concrete, asphalt, and certain types of paving, which are commonly found in roads, parking lots, rooftops, and driveways. Because impervious surfaces restrict water from being absorbed by the soil, they can contribute to increased stormwater runoff, leading to flooding, erosion, and water pollution. The excess runoff often carries pollutants such as oil, chemicals, fertilizers, and debris into stormwater systems, impacting water quality. Managing impervious surfaces is crucial to mitigating these environmental impacts.

Key amendments include:

• Requirements for municipalities and other public entities to provide mapping and recordkeeping, including maintenance and inspection records, for stormwater infrastructure systems connecting to, draining to, or collecting runoff water from public right-of ways by December 31, 2026. Recertification of stormwater infrastructure will be required by 2028 and in 10-year increments thereafter.
• Improvement of stormwater retention requirements for private and public developments, redevelopments, and substantial improvements to address water quality and flood control.
• Establishment of an Impervious Surface Permit for the installation, replacement, or expansion of non-structural impervious surface improvements, including single-family and duplex properties. Impervious surfaces include roof extensions, swimming pools, highly compacted ground or fill, and the installation of certain pavers, concrete slabs, and other materials that reduce the amount of pervious area, as defined by Chapter 24 of the Code of Miami-Dade County.
• Establishment of minimum permeability requirements to ensure that alterations to existing properties do not adversely impact their neighbors with respect to stormwater discharge.
• Update to dewatering standards, including clarification of the requirements applicable to residential swimming pools.

The Ordinance amends Chapter 24, Chapter 33, and Chapter 8CC-10 of the Code of Miami-Dade County which includes revisions and additions to the development standards and operational procedures for drainage infrastructure, non-structural impervious surfaces, and water quality protection.