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Fairfax County has issued new guidance for homeowners dealing with beavers whose dams and tree-cutting can flood property, block road culverts and damage vegetation.
The educational material follows a June board matter introduced by Hunter Mill District Supervisor Walter Alcorn. It explains the county’s responsibilities, applicable laws and ways residents can protect private property while preserving the ecological benefits beavers provide.
Conflicts can arise when beaver activity leaves stumps that create tripping hazards or causes flooding capable of undermining roadbeds and prompting repairs. Yet the county recommends nonlethal management instead of killing the animals.
Powerful ecosystem engineers
American beavers, or Castor canadensis, are considered a keystone species because their work reshapes habitats for many other animals. Their dams can moderate downstream flooding, recharge groundwater and create wetlands that filter water, capture silt and remove toxins.
By slowing moving water, dams can also stabilize stream banks, encourage vegetation and reduce erosion. Beaver ponds provide habitat for fish, amphibians and birds while supporting irrigation, flood control and resilience during droughts.
Second only to humans in their ability to transform landscapes, beavers usually weigh 10 to 30 pounds, though some grow larger. They have waterproof dark fur, webbed feet and broad, flat tails. They can remain underwater for as long as 15 minutes.
Their large orange incisors grow continuously and must be worn down through daily chewing. Trees damaged by beavers often show clean, axe-like cuts at roughly a 45-degree angle.
Protecting trees and controlling water
For valuable trees, the county recommends wrapping trunks with 14-gauge galvanized welded-wire fencing with 2-by-4-inch mesh. The barrier should extend four feet upward and leave six to 12 inches between the trunk and fencing to accommodate growth. Its ends can be bent together or fastened with hog rings or zip ties.
A single larger fence can protect a cluster of shrubs or a grove of trees more efficiently than separate guards around every trunk.
Another possible deterrent for mature trees—but not saplings—is a mixture of 20 ounces of coarse mason’s or playground sand, measuring 30 to 70 mil, per gallon of exterior latex paint. The mixture should be stirred frequently and applied from the base of the trunk to a height of about three or four feet.
Flood-control options include exclusion fencing and devices that regulate pond levels. Available designs include beaver baffles, beaver deceivers, Clemson beaver pond levelers, diversion dams, keystone fences, starter dams, and fence-and-pipe systems.
Simply breaking or removing a dam is unlikely to solve the problem. Beavers associate the sound of running water with a breach and may rebuild the structure within 24 to 48 hours.
State law limits removal
Any work affecting streams, wetlands, floodplains, protected waters or Resource Protection Areas must comply with local, state and federal permitting and land-disturbance rules.
Occupied beaver lodges and bank dens cannot be removed under Virginia law. The state also prohibits relocating beavers.
Trapping is considered lethal control. A trapped beaver must either be released on the same property or humanely killed if removed from it. Fairfax County’s Animal Protection Police and Wildlife Management Office do not trap or remove nuisance beavers.