A number of submerged plants flourish in stormwater ponds in South Carolina because these ponds are typically shallow enough that sunlight can penetrate all the way to the bottom. Stormwater ponds also receive repeated inputs of nutrients through runoff from lawns and roadways each time it rains. The combination of shallow water, sunlight and nutrients makes for the ideal habitat for submerged vegetation.
Submerged plants provide many ecological services, such as:
However, when submerged vegetation grows in excess, it also can cause problems, such as:
Should all submerged vegetation be removed from my pond?
No. Submerged vegetation is essential to protecting the ecological integrity of the aquatic environment.
Are there any particular plants that should be removed entirely from stormwater ponds?
Yes. There are a number of submerged plants that are extremely invasive and should be eliminated if possible. These include plants such as Hydrilla, Eurasian Watermilfoil, and Brazilian Elodea. These, along with several other plants, are illegal aquatic plants in South Carolina, making it against the law to possess, sell, or introduce these plants. For a list and descriptions of South Carolina's illegal aquatic plants, click here.
How much submerged vegetation is too much?
Submerged vegetation should be restricted to the littoral zone (the shallow areas around the perimeter of the pond) because most cannot grow in depths greater than 4 feet. Submerged vegetation should be managed to prevent it from covering more than 20% of the pond, and it should be prevented from "topping out" (ie., reaching the water surface) where possible. Also, submerged plants should be managed around inlets and outfalls to prevent blockages.
What are the best ways to manage submerged vegetation?
Use integrated pest management: