In the last three decades, man-made “ponds” have become as much a part of the landscape of coastal South Carolina as the rivers, creeks, marshes and the Atlantic Ocean.
The ponds are in shopping centers, office complexes, subdivisions and public properties.
The engineered structures have made it possible for masses of people – which have brought more rooftops, more parking lots, more roads and driveways and other impervious surfaces – to move to the Lowcountry without creating chronic flooding problems or completely ruining the waterways that helped bring them here in the first place.
The artificial ponds contain runoff contaminants that would otherwise go into natural waterways.
According to experts, nearly 10,000 ponds have been built to handle stormwater retention or detention in the eight coastal counties of the Palmetto State. And another 10,000 have been built for recreational or agricultural purposes.
With that many being built in such a relatively short period of time, they become a subject of concern, from the array of pollutants collecting in them to the inevitability of dredging them.
“Ponds, by their very design, fill in,” says Dr. Erik Smith, a research coordinator at the University of South Carolina’s Belle W. Baruch Institute for Marine and Coastal Sciences in Georgetown.
“We all jokingly say that all ponds want to grow up to become swamps.”
But if allowed to do so, the ponds constructed for storing and/or slowly releasing stormwater lose their main purposes for existing in the first place: flood control and preserving water quality.
Guinn Wallover, water resources extension agent for Clemson Extension, underscores the importance of the ponds and their connectivity with the waterways that support “our Lowcountry way of life.”
“There is a concern that poorly-maintained ponds could act as a pollution source to our downstream waterways, impacting their ecologic health and our community’s economy and well being,” she says.
Wallover adds that effective pond management does not just require action by those living directly next them, but the entire community.
Ultimately, the question becomes when dredging becomes necessary, who will pay for it? In most cases, it won’t be the developers who dug them in the first place nor the governments that required them.
Rather, the burden will fall on the current property owners or homeowner’s associations.
Natural gems or “cess pools”
The size, quality and beauty of these water bodies run across the spectrum.
Some look like and are even “marketed” by developers as nearly natural lakes, with aquatic vegetation and beautiful wildlife, while others collect plastic trash and get gunked up with algae. The latter often also hosts wildlife, such as geese and ducks, that without proper landscaping can make matters worse.
“If you dig a hole in the ground, biology will happen,” says Smith. “You may think of these things as engineered structures, but they quickly develop some kind of ecosystem. Sometimes it’s a highly dysfunctional ecosystem, but sometimes an aesthetically-appealing ecosystem.”
And while the original intent of the ponds has been on handling a certain quantity of stormwater, increasing attention is being given to the quantity of water.
Smith is among a collaboration of professionals from academia, government, business and nonprofits who are working to solve some of the coming problems and opportunities presented by the ponds.
Besides USC’s Baruch institute, those organizations include College of Charleston, Clemson Extension’s Carolina Clear and Ashley Cooper Stormwater Education Consortium, S.C. Department of Natural Resources and Charleston Waterkeeper.
South Carolina Sea Grant Consortium has pulled together experts, some of whom are currently conducting studies on the pond systems, to create a 10-12 chapter “state of the knowledge” report, expected to be finished this summer.
The report will be written in a reader-friendly way in an effort to help provide guidance to the guardians of ponds, such as homeowner’s associations.
Even before publication of that book, efforts are already underway to demonstrate how ponds can function better and provide a cleaner habitat for the wildlife that inevitable move into them.
One example is a demonstration project at the Charleston County offices off of Leeds Avenue where visitors can see a “forebay” and how it functions.
Basically, a constructed forebay is a reservoir of water in front of a larger body of water. The forebay, constructed strategically near a major pipe or culvert, impounds the water and releases it in a controlled way into the larger waterbody, thereby trapping more of the sediment and contaminants in a smaller area.
The county demonstration project also shows how the use of a buffer along the edge of a pond can also provide benefits, from slowing the flow of water, as well as absorb and filter it.
Planting a buffer
One way to improve to the function of ponds is by creating a vegetative buffer along the outer edges, according to experts.
While all ponds differ in size, Smith says most would benefit from not mowing to the pond edge, planting an edge with appropriate vegetation and creating a relatively shallow, gently sloping “shelf” around the edge for plants.
“We tend to dig ponds as bathtubs with no vegetation on the ground,” says Smith. “There’s a variety of vegetation that could be promoted and allowed to establish along the edge.”
Locally-based civil engineer Joshua Robinson, who is founder and principal of Robinson Design Engineers, calls retrofitting existing ponds “as low-hanging fruit” in improving stormwater quantity and quality controls in the Lowcountry.
Robinson tapped into the power of native plants when designing the drainage plan for the “infill” development, the nine-house Fox Hollow, on James Island. He created a “a stormwater wetlands” that is an ecologically-appropriate mix of open water, shallow marsh and shoreline.
The one at Fox Hollow includes include bald cypress trees, beautyberry shrubs and juncus, a native rush that thrives in wet areas such as ditches.
Robinson says plants play a role in “evapotranspiration,” the process in which plants soak up water from the land and transfer it to the air.
The side benefit of structure is that the area has become a small wildlife habitat.
Robinson says more clients, particularly in urban areas outside of South Carolina, are demanding that the stormwater control systems offer more in terms of nature.
“It’s happening in other parts of the country,” says Robinson, of a growing cultural value for green space. “This is becoming business as usual.”