What are Stormwater Control Measures?

Published on June 22, 2026

 

When it rains, water runs off roofs, roads, parking lots, lawns and many other surfaces. This is called stormwater runoff.  Stormwater runoff can carry pollutants into creeks and lakes, impacting water quality and aquatic life. When too much runoff enters waterways too quickly, it can also contribute to flooding and stream bank erosion.

To help manage this, The City of Charlotte and Mecklenburg County ordinances may require the construction of Stormwater Control Measures (SCMs) with new development. These are engineered systems that can store and slow down stormwater, reducing flooding, erosion and pollutant loads before the stormwater reaches local waterways like creeks, rivers and lakes. While the primary purpose of SCMs is to manage stormwater runoff, some types, particularly constructed rain gardens, wetlands and wet ponds, can also provide a secondary benefit by creating habitat for a variety of plants and animals.

Stormwater Control Measures may be required for a variety of projects, from single-family home projects to new residential and commercial developments. Depending on the location, responsibility for maintaining these systems may belong to a homeowner, business owner, homeowners’ association, or other property owner. While many SCMs go unnoticed, they play an important role in reducing flooding, preventing erosion and protecting the health of our local waterways. 

Common Types of SCMs

 

1. Wet ponds: These are permanent ponds that hold water all the time. They collect stormwater and let dirt and pollutants settle to the bottom.

Pond with rippling water surrounded by grass and trees.

Wet Pond

2. Bioretention cells (also called rain gardens): These are landscaped areas designed to collect stormwater runoff and allow it to be filtered through soil and a special engineered soil media. Plants are often included and help with uptake and filtration, but some bioretention areas may have grass or sod instead of traditional garden plantings.

Landscaped planting area with dense vegetation, soil and rocks.

Bioretention Cell (Rain Garden)

3. Permeable pavers: These are special paving stones that allow water to pass through gaps into the ground instead of running off and flowing into nearby storm drains.

Interlocking pavers forming a walkway next to landscaped grasses and a parking lot.

Permeable Pavers

4. Sand filters: These systems use engineered sand media to filter stormwater and remove pollutants before being released to nearby creeks. The top surface can vary and may include sand, gravel or grass.

Grassy landscaped ditch with a concrete structure and gravel surface.

Sand Filter

5. Wetlands: These are constructed wetlands designed to mimic the function of natural wetlands. The storage, areas of varying depths, and different plant species in stormwater wetlands, work together to remove many of the pollutants found in stormwater runoff while also providing habitat for a variety of wildlife species.

Grasses and wetland plants growing in and around a shallow pond area.

Wetland

6. Dry detention basins: These are basins that stay dry most of the time but are filled with water during storms. They slowly release the water after the rain stops and allow some pollutants to settle out.

Large grassy basin surrounded by trees and gently sloping banks.

Dry Detention Basin

7. Underground basins: These operate similarly to their above ground equivalents but are built underground to save valuable surface space. They may have similar design features (like sand filters) to assist in meeting stormwater runoff treatment requirements.   

Excavated area showing installation of underground water storage structures.

Underground Basin

Related Links

calendar icon Learn More at Storm Water Services
calendar icon Stormwater Control Measure (SCM) Owner? Know Your Responsibilities
calendar icon Stormwater Control Measure (SCM) Design Manual

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