On Tuesday, June 13, the annual eradication efforts began for invasive water chestnuts (trapa natans) in the tributaries of the Sassafras River. The European water chestnuts (not the delightfully crunchy kind we find in Chinese food) first appeared in the Sassafras River in 1964. Various eradication efforts have occurred since then, and in 1999, approximately 400,000 pounds of plants were mechanically and hand-harvested from the Sassafras and the Byrd River across the Chesapeake Bay.
Water chestnuts are a particular problem because the seed pods of the exotic plants can live up to 12 years in the mud before sprouting. When sprouting occurs, a thin stem emerges from the creek bed and quickly finds its way to the surface, where two things happen: leaves form as tiny rosettes, and football-shaped spongy growths form along the branches - which serve to float the entire plant.
As the plant continues to grow on the surface of the water, the rosettes enlarge and mesh together which creates mats of vegetation. The thick mats greatly impede boaters, fisherman, water skiers and swimmers, and these limitations on water use can negatively impact real estate values.
As sunlight is blocked, the habitat is destroyed for beneficial native grasses. Underwater vegetation is critically important to the health of the river because they stabilize the sediment runoff from erosion, provide habitat protection for small fish and crabs, provide food for river critters and migratory waterfowl, and refresh the water with oxygen.
When the plants die in the fall, T. natans can deplete the dissolved oxygen in the water, and the resulting low oxygen condition (anoxia) can lead to fish kills and harm other aquatic organisms.
Each June and July, the Sassafras River Association joins with the Maryland Department of Natural Resources to bring staff and volunteers to remove as many plants as possible from the creeks around the Sassafras. The plants grow in shallow water, so we use kayaks, canoes, and jon boats to reach the chestnuts.
If you are interested in volunteering, please call our RIVERKEEPER™ Emmett Duke, at 410-275-1400.
Find more information about water chestnuts here.