Installing the Receiver Fence
Installing Corner Posts
Cutting points on the corner posts makes it easier to pound them into the substrate.
Sharpened corner posts at the water's edge.
Installing the first post and adding bracing.
Using stringers to determine where the rest of the corner posts should go.
Using a step ladder to pound the corner posts into the substrate with a sledge hammer.
The receiver fence is installed at the mouth of the fish ladder (or a culvert mouth in a more typical situation). The first two posts are located on either side of the top of the outlet and are as close to the opening as possible. In this situation we installed them right at the ends of the metal railing that defined the edges of the trash rack at the entrance of the fish ladder/outlet control structure.
The other corner posts should be placed with the site specific characteristics in mind. The area defined by the receiver fence may be any size - but the larger the better, and it may be any shape, though Skip has found that shapes that flare out from the outlet in a trapezoidal manner are most effective. At Peterson Pond, space was not limiting though bottom depth was beginning to be, so the simplest shape was one that had four corners, flared out from the edge of the trash rack and which had sides and an upstream end each equal to half of a length of fencing material. This shape simply minimized the amount of cutting needed to fit the fencing to the posts while still maximizing the optimal trapezoidal shape.
An additional consideration is the height of the fence. The fence should extend above the high water line at least 2 feet to prevent beavers from clambering over with branches. You will need to know the water depth. The fencing material is 7.5 feet wide and in most applications this will be sufficient to reach the bottom and still extend above the high water line by about 2 feet. Typically the limiting factor will be the depth of water in which one can still work using manual labor and hand tools. The size of the receiver fence at Peterson Pond was based on the ability to construct the fence using chest waders.
Post ends are sharpened with a chainsaw to make installation easier. Sharpened posts can be driven into most substrates with a sledge hammer. Posts are braced with 2 X 4's or 2 X 6's. The bracing boards should be sliced at an angle to create sharp points on the ends. The sharp points again are driven into the substrate and the upper ends are nailed into the corner posts.
Installing the Footing
Cutting and bending the fencing material to create a footing.
Footing is ready for installation.
Installing the footing.
A footing is required along all of the outside edges at the bottom of the receiver fence to prevent beavers from easily digging under the vertical fence and reaching the outlet with branches and debris. A footing is easily created by cutting off a five "square" wide section of the fencing material. Cut the wire between the short lengths to create a three "square" wide fence with "prongs" on each side running the whole length of the footing. Bend these "prongs" so that they are at right angles to the main body of the fence. Bend the prongs on each side in the same direction. These prongs will be placed down when the footer is installed to hold the footing in the place in the substrate along the bottom of the fenceline. When the footing is in place, step or jump firmly on the footing to seat the prongs well into the substrate along the entire length. If the substrate is very hard, you can enclose the bottom of the receiver fence area instead, to prevent the beavers from getting inside the receiver fence.
Attaching the Stringers and Side Fencing
Attaching the stringers to the side posts.
Cutting the fencing to match the contours of the pond bottom.
Attaching the fencing to the sides of the receiver fence.
"Prongs" on the bottom of the fencing to seat into the substrate.
Fence is attached to the corner posts and the bottom of the stringers with staples.
Last section being lowered into place. Note the hole cut out for the pipe to extend through.
Attach the stringers to the corner posts at a height that will both allow the fence to reach the bottom of the pond securely as well as extend at least 2 feet above the high water mark. The top of the fencing will be secured to the bottom of the stringers with staples, so include this consideration when deciding the placement of the stringers.
Cut the fencing to roughly match the contours of the bottom. Crosswise wires are cut out close to the bottom to create "prongs" that can be pushed down into the substrate to further secure the bottom edge of the receiver fence.
Since it was not practical to reduce the noise generated by the control structure/fish ladder and the size of the receiver fence was limited by the water depth, it was determined that the beaver might attempt to dam around the receiver fence. A hole was cut in the upstream section of fence to allow a pipe to extend into the pond. If the receiver fence does become blocked over time, the flow will be maintained through this pipe. A round fence will protect the upstream end of this pipe from beaver activity.
Next Page: Installing the Pipe and Round Fence