The muskrat (Ondatra zibethicus) is a medium-sized, semi-aquatic rodent common throughout North America’s wetlands, ponds, and lakes. While they are a natural part of the ecosystem, their behavior of building extensive burrow systems into banks and earthen dams causes significant structural damage and erosion. These burrows compromise the integrity of shorelines, levees, and pond infrastructure, making effective, non-lethal deterrence a priority for property owners.
Recognizing Signs of Muskrat Activity
The first step in deterrence is confirming that muskrats are the cause of the damage, as they are often confused with larger animals like beavers or nutria. Muskrat burrow entrances are typically small, five to six inches in diameter, and are almost always located six to twelve inches below the water’s surface. Beaver and nutria entrances are significantly larger, often ranging from 14 to 20 inches in diameter.
Muskrats also leave behind distinct signs related to their feeding habits and movement. Look for narrow, worn trails, often called “runs” or “slides,” that lead from the water’s edge up the bank. They construct small feeding platforms, sometimes called “push-ups” in winter, which are elevated piles of mud and aquatic vegetation where they consume their food. These platforms often contain remnants of their preferred diet, which consists mainly of aquatic plants like cattails, bulrushes, and water lilies.
Deterrence Through Habitat Manipulation
Deterrence begins by making the shoreline habitat less appealing for muskrats to establish a home. A highly effective method involves eliminating their primary food sources near the water’s edge. Muskrats rely heavily on dense stands of aquatic vegetation like cattails and rushes, so removing these plants from the immediate shoreline area forces them to look elsewhere for sustenance.
Altering the slope of the bank can also discourage burrowing, as muskrats prefer banks that offer a steep incline for their tunnels. When constructing or repairing a pond, grading the bank to a gentle slope of 3:1 or shallower makes it more difficult for them to dig their burrows. This shallower angle reduces the risk of burrow collapse and makes the bank less structurally sound for their den construction.
Managing the water level within the pond or lake can disrupt a muskrat’s established burrow system. Muskrats build their den chambers above the water line. Fluctuating the water level by drawing it down by at least two feet during the winter can make a den site inhospitable.
Chemical or odor-based repellents are generally impractical and ineffective for long-term muskrat deterrence in large aquatic environments. The continuous flow and volume of water quickly dilute or wash away topical applications. Focusing on physical habitat changes provides a more reliable, permanent solution.
Installing Structural Exclusion Barriers
When habitat modification is not sufficient or feasible, installing physical barriers offers a permanent solution to prevent burrowing damage. One common and effective structural method is the application of riprap, a layer of heavy stone or large rocks placed along the bank. For maximum protection, this riprap should extend from at least one foot above the normal water line down to a depth of three feet below it.
The stone layer should be at least six inches thick, and the individual stones must be large enough to prevent muskrats from moving them or creating cavities underneath. Using smaller stones can inadvertently create inviting spaces for muskrats to shelter. This heavy, impenetrable layer physically blocks access to the earthen bank or dam structure.
Another highly effective method is burying a barrier of heavy-gauge wire mesh or hardware cloth into the bank. The mesh should have openings no larger than one inch. This material must be installed vertically, extending at least one foot above the water line and a minimum of three feet into the bank below the water line.
For larger, more permanent installations like high-value dams, a vertical barrier such as a concrete or wooden seawall may be necessary. A concrete barrier can be installed by cutting a trench down the center of the earthen structure and filling it with concrete, ensuring the barrier extends well below the muskrat’s typical burrowing depth. These solid structures provide complete exclusion from the bank face.
Legal Requirements and Safe Removal Options
If deterrence methods fail and muskrats continue to cause significant damage, removal may become necessary, but this process is subject to strict local and state wildlife laws. Muskrats are classified as furbearers in many jurisdictions, meaning their trapping and removal are regulated by specific seasons and licensing requirements. It is imperative to check with the state fish and game agency or local Department of Natural Resources (DNR) before attempting any removal.
Some states allow landowners to take nuisance muskrats outside of the regular trapping season if they are causing property damage, though this often requires a specific permit. Relocation of captured animals is frequently prohibited, as moving wildlife can spread disease or shift the problem elsewhere. If live trapping is permitted, the animal must often be euthanized or released on the property of capture, depending on local regulations.
For severe or persistent infestations, consulting a licensed Wildlife Control Operator (WCO) is the recommended course of action. These professionals possess the necessary permits, knowledge of local laws, and specialized equipment to humanely and legally remove the animals. They can also implement the structural and habitat modifications needed to prevent future recurrence.