Foiling the Wily Muskrat
by Joyce Deaton

“What? You’re going to ruin my business,” says Kevin Vaughan with a laugh when he hears Pilot has called for tips on how to prevent muskrats from ravaging docks. Vaughan, who’s been building and repairing docks on Lake Norman, Lake Wylie and Mountain Island Lake for 25 years, even named his company Muskrat Marine Construction out of respect for the pesky critter.

The muskrat doubtless is worthy of respect. He figures in several Native American creation stories. According to the Blackfoot tribe, the creator was curious about what was under the water. Several animals dove down to see, but couldn’t make it to the bottom. The muskrat dove and came up holding between his paws a small ball of dirt. He blew on it, and it began to swell. Thus the earth was created.

The legend may have grown out of the muskrat’s peculiar ability to swim underwater longer than other mammals. Its nostrils, shaped like a “7,” allow it to inhale extra oxygen from recently exhaled air, and it can swim up to 15 minutes underwater, propelling itself with its strong, flat tail. Its hind feet are webbed, and its front feet are small and agile, more like hands.

Muskrats feed on cattails and other vegetation, helping to maintain open areas in marshes for aquatic bird habitats. They also eat mussels and other tiny water creatures, and they burrow into the ground next to the water to create a system of tunnels that make their home.

And there’s the rub. Muskrats love to burrow into the styrofoam floats that hold up docks, eventually causing structural damage and leaving dock owners feeling anything but respectful. Some take drastic steps such as poisoning, trapping or shooting muskrats, but Vaughan, concerned for the animals and the environment, says simply, “I hate to see that.”

Turns out it’s not even necessary, since there’s a simple man-made solution. “The problem is with the older styrofoam flotation – the white and blue kind. It’s a magnet for muskrats. They love it,” says Vaughan. Replacing that material with a newer black polyethylene product – he favors one called Formex® – effectively baffles the muskrats.

Formex® is made from high-density polyethylene, which is also used for automotive gas tanks and canoes. Its hard shell, which is resistant to impacts and impermeable to water, protects an inner foam core from waves, animals, marine organisms and gasoline. The foam inside is a pre-molded block that’s bonded to the outer shell, so there’s no loose fill and no voids that can fill with water and reduce buoyancy. The hard, smooth shell prevents muskrats from getting a toehold and sends them elsewhere for their burrowing. Vaughan says the new material is recommended to marine contractors by the US Corps of Engineers and Duke Energy and soon will be required for all docks. It also lasts longer than styrofoam, with a 12-year limited warranty.

Existing docks can be updated by removing the styrofoam and replacing it with the new black floats. “We’ve done this with a lot of docks – some 30 years old – that would have had to be torn down, and they’ve lasted another five to 10 years,” says Vaughan. “When eventually the owners have to build a new dock, we can just pull out the black flotation and re-use it.”

Vaughan offers another tip for discouraging the wily muskrat: Eliminate junipers and bulbs such as daffodils and tulips, which they consider especially tasty, from waterline plantings.

Though there are stories of alligators imported from Florida and other scary sights at dockside, Vaughan says the only other ones he’s met are snakes. The same solution works to discourage them. “For some reason, the snakes like the white foam, and to some extent the blue kind, but they won’t come around the black,” he says.

While water moccasins are known to inhabit the lower reaches of the Catawba River, Vaughan isn’t sure what kind of snakes he’s encountered. He doesn’t stick around long enough to interview them. “I’ve found out I can walk on water,” he says.