The water moccasin, also known as a cottonmouth (Agkistrodon piscivorus), is a venomous snake commonly found in wetlands, swamps, and retention ponds throughout the southeastern United States. As the most aquatic of the pit vipers, it is drawn to water features for food and shelter. Proactive environmental modifications are the most effective way to deter their presence, starting with understanding the snake’s habits and appearance.
Confirming Identification and Danger
Accurately identifying a water moccasin is important, as many harmless water snakes are often mistaken for them. Water moccasins possess a thick, heavy body and a large, blocky, triangular-shaped head that is noticeably wider than the neck. As pit vipers, they also have vertical, cat-like pupils and visible heat-sensing pits, though observing these features closely is not advised.
Harmless water snakes, such as those in the Nerodia genus, generally have a more slender body profile and a rounder head that blends smoothly into the neck. While a non-venomous water snake may flatten its head into a triangle when threatened, it will appear flattened rather than thick and bulky. Another distinguishing feature of the cottonmouth is its namesake defensive display, where it throws its head back and opens its mouth wide to reveal a stark white, cotton-like interior.
The water moccasin’s venom is primarily hemotoxic, attacking and destroying blood cells and surrounding tissue. Envenomation causes intense localized pain, swelling, and internal bleeding, often with systemic effects like nausea and a drop in blood pressure. While fatalities are rare, a bite is a serious medical emergency requiring immediate professional treatment.
Exclusionary Measures for Pond Environments
The most effective method for keeping water moccasins away is making the pond environment unattractive by eliminating cover, basking spots, and food sources. Maintaining a clear, open zone immediately surrounding the water body removes potential shelter. This increases the snake’s exposure to predators and forces it to move elsewhere.
Start by eliminating all non-essential ground cover, including rock piles, construction debris, and stacks of firewood near the pond’s edge. Keep the lawn surrounding the pond consistently mowed to a low height, as tall grasses and overgrown brush provide excellent hunting and basking cover. While native shoreline plants are important for preventing bank erosion and filtering water, any dense, low-hanging tree branches or shrubs directly overhanging the water should be trimmed back.
Modifying the pond’s bank structure can also create a physical deterrent to entry. Snakes prefer a gradual slope that allows for easy access to and from the water. Instead of a gentle incline, creating a pond bank with a steep, clean vertical edge or a smooth, hardened surface makes travel difficult for a snake. If a retaining wall is installed, ensuring a smooth surface with a slight overhang can be an effective physical barrier to climbing.
Controlling the population of prey animals is important, as food is the primary reason snakes visit a pond. Water moccasins feed on fish, frogs, lizards, turtles, and small mammals, so managing these populations decreases the pond’s appeal. This also includes controlling rodent populations by removing potential nesting sites and securing outdoor pet food.
A physical barrier like snake-proof fencing can be installed around the pond’s perimeter. This specialized fencing should be fine-mesh material, with openings no larger than a quarter-inch, and must be at least 30 inches high. For effectiveness, the bottom edge of the fence should be buried several inches into the ground and angled outward to prevent crawling underneath or climbing over.
Many commercially available chemical repellents, such as those containing sulfur, naphthalene, or mothballs, are not effective against water moccasins. These products offer inconsistent results and require frequent reapplication, making them an unreliable solution. Furthermore, using these chemicals near an aquatic environment can contaminate the water and harm the pond’s ecosystem, often violating label instructions.
Safe Handling and Professional Removal
If a water moccasin is sighted near or in your pond, the immediate priority is to maintain a safe distance and avoid any attempt at confrontation. The vast majority of venomous snake bites occur when people try to capture, handle, or kill a snake. Simply back away slowly and calmly, giving the snake a wide berth, and never attempt to corner it.
Never try to relocate the snake yourself, as handling venomous reptiles may be restricted by local wildlife regulations. Even dead snakes can possess a bite reflex, posing a risk to anyone attempting to move them. Keep children and pets away from the area until the snake has been confirmed as removed.
If the snake poses an immediate threat or has taken up residence, contact a professional for safe removal. This includes local animal control, a licensed nuisance wildlife control operator, or a specialized venomous snake removal service. These professionals are trained to accurately identify the species and use humane, safe methods for capture and relocation, minimizing risk to people and the animal. When calling, provide a clear description of the snake’s location, size, and behavior to assist the professional.