Stormwater Ponds: Why Are They Everywhere in Horry & Georgetown Counties?
A Common Sight with a Critical Purpose
If you've driven through a new subdivision or commercial development in Horry or Georgetown County, you've probably noticed stormwater ponds—those engineered basins with sloped sides and often little to no water in them on a dry day. While they might look like decorative features or underwhelming water hazards, they're actually doing important work beneath the surface.
Stormwater ponds are a required component of most modern developments in Coastal South Carolina. They help manage runoff, control flooding, and protect downstream waterways from pollution and erosion. Without them, the region's flat topography and frequent storms would wreak havoc on roads, properties, and ecosystems.
Why Stormwater Ponds Are Needed
The development process transforms land in a way that increases impervious surface area—think roads, rooftops, and driveways. These surfaces prevent rainwater from soaking into the ground, resulting in more runoff than the land can naturally absorb. That’s where stormwater ponds come in.
Their primary functions include:
Detaining excess runoff during storms to prevent downstream flooding
Allowing sediment and pollutants to settle out before water is discharged
Slowing water flow to reduce erosion and protect infrastructure
Meeting state and local stormwater regulations, including water quality standards
The Continuity Equation: The Math Behind the Pond
Engineers use the continuity equation to design stormwater ponds:
Inflow = Outflow + Storage
This simple formula represents the mass balance of water in a pond. It ensures that the rate at which water enters the pond (inflow) during and after a storm equals the combined rate at which water is released (outflow) through pipes, weirs, or orifices, along with the temporary water stored (storage) in the pond basin.
By manipulating pond size, depth, and outlet configuration, engineers can slow down the outflow rate, ensuring that water exits the system in a controlled and non-damaging way. This is particularly important in the low-gradient landscapes of Horry and Georgetown Counties, where drainage systems can easily become overwhelmed.
Types of Stormwater Ponds
Detention Ponds – Temporarily hold runoff and slowly release it. These are the most common type and often appear dry between storms.
Retention Ponds – Designed to maintain a permanent pool of water. They offer water quality benefits and are sometimes incorporated into landscaping.
Dry Ponds – Similar to detention ponds but typically drain completely after a storm event.
Who Maintains Stormwater Ponds?
Stormwater ponds are typically maintained by:
Homeowners Associations (HOAs) in residential developments
Private property owners in commercial areas
Municipalities or counties (rare, and only in certain public projects)
Lack of maintenance can lead to:
Clogged outlets
Sediment buildup
Mosquito breeding
Structural failure of embankments or pipes
Why It Matters
Stormwater ponds are not just boxes to check off in a development plan—they’re essential infrastructure. When they fail, or when they're poorly maintained, the result can be flooded yards, damaged roads, and degraded wetlands.
For homeowners in Coastal South Carolina, understanding the role of these ponds is key to:
Protecting your property
Avoiding fines from regulatory agencies
Ensuring long-term functionality of your neighborhood’s stormwater system
So next time you pass a stormwater pond in Horry or Georgetown County, know that it’s more than just a ditch with a fence—it’s a hydrologic workhorse, carefully designed using engineering principles like the continuity equation to keep water flowing safely and sustainably. When done right, stormwater ponds quietly protect our communities from the worst nature has to offer.
