Beavers invented the ponds man imitates for everything from water storage for irrigation and fish culture, to hydro power, flood control, recreation, landscape design, wildlife habitat, refrigeration, and more. But when beavers fool with man-made ponds, watch out. Their instincts for building and plugging dams can trigger floods and pond destruction. Pond owners trying to accommodate beavers without resorting to lethal elimination often use control devices like Skip Lisle's "Beaver Deceiver", above. Note the decking over the baffle box, which can function as a pier, diving board, etc. And the beaver lodge across the water. For the scoop on preserving ponds and beavers read on.
I visited a couple of beaver troubled ponds this past summer. In both ponds the beavers were doing what comes naturally, packing the dam spillway to curtail overflow. Beavers are known to respond to the sound of discharging water by plugging the dam, and they were succeeding. In one case it was a leaky beaver-made dam they were fixing; the other was a man-made dam with a concrete drop box with a noisy sluiceway they wanted to plug. Maybe it wasn't just dam repair they were up to. The summer was drought dry -- were they were hoping to raise water levels and stop the pond shrinkage due to drought?
Whatever the motivation, in both cases they were successful. And it had the caretakers worried. The pond with the beaver dam (built on top of an older man-made embankment) had been enlarged with a higher water level that turned an adjacent brushy field into a shallow lagoon. The water was getting close to the house. In the other pond the water level was a foot or more higher than the designed discharge. In this pond the beavers had a record of plugging the spillway to the point that heavy rains in the past had overtopped the dam and flooded a nearby road.
While the owners of the flooding field were still contemplating what to do, the sluiceway caretakers did not want their dam breeching again. They called in beaver expert Skip Lisle, who lives not far south in Grafton, Vermont, and he fabricated and installed one of his famous "Beaver Deceivers" to protect the spillway from beaver damming, while still allowing it to discharge properly. The packing material (mud and sticks) had been removed, and with the Beaver Deceiver in place, the pond returned to its designed water level and surface size. In the other pond, the owners and the beavers seemed content with the current state of things. Fingers are crossed that flooding will be avoided.
What to do when beavers fool around with your pond presents an old and perplexing problem. Allowing them to raise water levels invites the possibility of flooding and possible pond loss, as well as the loss of surrounding trees to beaver needs for food and dam and lodge building materials.
But getting rid of beavers is easier said than done, especially for folks with a respect for wildlife, which is most pond owners.
If you're lucky, a beaver inhabited pond will have reached a status quo, with no
desirable food and building trees left to plunder. But if the dam is threatened, the owner may resort to beaver removal or worse. Sometimes trappers can be called in, and the beavers relocated (not always a successful move if the new place isn't suitable, which can happen for a lot of reasons...) Sometimes owners will use lethal traps or the flying lead solution, which many folks don't consider a solution at all.
And that's where a guy like Skip Lisle comes in. It's his job to help create the balance needed for beavers and people to coexist. And that usually means creating a way for the dam to discharge overflow as designed, without interference by the beavers.
How is it done? The object of a Beaver Deceiver or other anti-damming device is to allow the dam to overflow at the designed water level, while protecting the discharge from being plugged. Depending on the pond and dam involved, this may require a combination of fencing and piping to keep the beavers away from the discharge inlet.
Fencing and piping is often needed for a man-made dam and spillway. For a beaver dam, the solution might be as simple as installing one or more discharge pipes through the stick and mud dam. The pipe is installed at the desired pond water level, and protected against beaver plugging.
Other measures used to deter beavers include wrapping trees with wire fencing to prevent the animal from felling trees for dam and lodge building, or for food. Electric fencing for similar exclusion. And various scents, some applied to trees to make them undesirable, some located on shore to alarm beavers about competing beavers.
There's a lot of irony in the pond and beaver tug of water. Building a man made pond is basically borrowing an idea developed by beavers long before man ever came along, then polishing it up using new fangled piping and construction devices, and letting the pond fill. And just like beaver dammed ponds, plenty of man-made ponds need touching up now and then, and may even fail and flood out.
In the spirit of beaver camaraderie, I suggest pond caretakers expand your research from the tools of beaver control to include the history of this unique animal. Consider the many ways that ponds and dams have inspired mankind, from our first forays into crop irrigation and aquaculture, water supply for man and animal, then hydro power, flood control, recreation, landscape design, wildlife habitat, refrigeration, and more. Where did these ideas originate? With beavers.
I have done a lot of reading about beavers since I got started in the pond business, but there hasn't been much new over the past couple of decades. Until now. I've been delighted and impressed by a new beaver book that breaks new ground in beaver history and the latest research and management practices. It's called Eager, the Surprising, Secret Life of Beavers and Why They Matter, by Ben Goldfarb. And I can't think of a better book to recommend for pond owners, or anybody who loves the outdoors, or even American history. After all, if it weren't for beavers we humans might not be here at all, certainly not in any way, shape or form similar to our current status. I'll be reviewing Eager in next month's Pondology, but why not get a head start and discover it for yourself. For the link to the best new pond and beaver book in ages: click here.
Originally published in November 2018
For more information on beaver issues
in Vermont, see article in August 2020 Vermont Digger
Topics vary from month to month and provide great information when researching where you want to build a pond, or how to keep it clean. Other areas of interest are pond use for more than swimming, and how to keep fish happy in your pond.