Monday, August 13, 2012

The Beaver Deceiver......

Aah, those beavers, one must deceive them to avoid flooding the trail and our neighbors property along Rt 7 in Sheffield.  See Adam Brown's report on the mucky business below.

ATC was approached in late fall of 2011 by a business owner whose property abuts National Park Service AT land in Sheffield, MA.  He reported that beavers on the NPS side were flooding his construction yard and threatening to inundate his septic mound.  Both ATC and the AT Committee were aware that flooding was happening on the trail itself and had been in to take a look at the area to see if any immediate solution was available, but were not aware that a neighbor was being affected.  After some discussion between NPS and MA Fish and Wildlife, we came up with several options: do nothing, hire a trapper to remove the beaver and kill it for its pelt (the state does not allow for relocation), or hire a contractor to install a flexible pond leveler (also called a “beaver deceiver”) device.  The first option was likely to alienate the neighbor; the second was harmful to the beaver, so we settled on the third option in hopes of being able to co-exist peacefully with the beaver. 

ATC and the AT Committee pursued a grant through MA Society for the Prevention of Cruelty to Animals (MSPCA), as well as the appropriate town/state Wetlands Protection Act permits, that would allow for cost-free construction and installation of the device by Mike Callahan of Beaver Solutions.  Below is a diagram and description of the device we installed.  We will plan to monitor the area over the fall and into next spring to see if it works.  When we installed it on Friday, water was very low due to the dry summer and the fact that the railroad company had recently replaced their culvert upstream in a way that prevents water at the current level from passing onto NPS land.  This will likely not be the case in a rainy year.   

Mostly Empty Pond, Beaver dam far side of mud hole!
Assemblying the Deciever

Floating the whole shebang into position
Submergence, ready for deception...

Readying the pipe for burial in the dam

So, here's how the whole thing works:

The Flexible Pond Leveler

Courtesy of Beaver Solutions LLC

May be reproduced

Where flooding from a free-standing beaver dam threatens human property, health or safety, a Beaver Solutions Flexible Pond Leveler™ pipe system can be an extremely effective solution. If properly designed and built, a Flexible Pond Leveler™ will create a permanent leak through the beaver dam that the beavers cannot stop. Our Flexible Pond Leveler™ devices are so effective we guarantee them. They eliminate the need for repeated trapping despite the presence of beavers.

Sorry folks, just can't figure out how to get the diagram to print in this space!

In order for these pipe systems to be effective, they must be designed so that beavers cannot detect the flow of water into the pipe. The Flexible Pond Leveler™ does this by surrounding the submerged intake of the pipe with a large cylinder of fencing. Beavers cannot get close enough to the intake to detect water movement. As a result, the beavers do not try to clog the pipe, and maintenance is rarely needed. A minimum pond depth of 3 feet is needed for the Flexible Pond Leveler™ to function properly.

The height of the pipe in the dam determines the pond level (see diagram). Water will flow through the pipe unless the pond level drops below the peak of the pipe. The pipe is set in the dam at the desired pond level, and can be adjusted up or down if desired.

Unlike road culverts, Flexible Pond Leveler™ pipes do not need to be sized to handle catastrophic storm events because heavy storm runoff will simply flow over the top of the dam. Following the storm the pipe will return the pond to the normal level. Some mild pond fluctuations are possible following very wet periods, but the pond will be controlled at a safe level since the dam height is controlled by the pipe.

When installing a pipe system it is very important to lower a pond only enough to protect human interests. The more a pond is lowered the more likely it is beavers will build a new dam to render the pipe ineffective. Lowering a beaver pond by up to one vertical foot is generally not a problem.

Whenever a pond must be lowered by more than one foot, a single round of trapping may be necessary prior to the flow device installation. When new beavers without the memory of the higher water level relocate to this area they are more likely to tolerate the smaller pond. Most Flexible Pond Leveler™ failures are due to new downstream damming in response to a dramatic lowering of the water level.

 So, there you have it!  Let's hope it works, and Adam, if you get a picture of the pond refilled with our recent rains with the elevation limited by the Beaver Deceiver, send it along and we'll add it to this post!

Great fun in the muck and mire!

Posted by Jim for Adam Brown

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