Various Flow Devices to Protect Culverts, Sluiceways and Drains
Beavers need deep water for protection and survival. They like to build dams where a relatively small amount of work will create a large pond. Therefore, road culverts, manmade dam sluiceways, and drain pipes are preferred damming locations for beavers. Fortunately though, most culverts and other manmade drainage structures can be protected from beaver damming with flow devices. Which type of device is most appropriate is determined by the specific site characteristics.
If water deeper than 3 feet is tolerable upstream of the structure, then a Fence and Pipe device is likely your best option. If you need to keep the water at the original stream level, then a Culvert Protective Fence is probably your best option. If a beaver pond is tolerable upstream of the drainage structure provided the structure remains completely open, then a Starter Dam may be the easiest and least expensive flow device to install. See the descriptions and photos of these devices below.
Culvert Protective Fences
Culvert Protective Fences are most commonly installed on road culverts. They are built in various shapes and sizes depending upon the topography of the stream channel, water depth and stream flow. They keep the stream at its original level, and are ideal for sites that cannot be ponded. They work by turning the culvert from the easiest place for beavers to dam into the hardest. This encourages the beavers to dam elsewhere, leaving the infrastructure undammed. Properly designed and installed Culvert Fences have a 95% success rate, and typically only require one hour of maintenance per year.
Fence and Pipe Device
The Fence and Pipe flow device is the most common method to protect road culverts and manmade drains. It allows beavers to have but limits the height of the water at a safe level. Beavers can dam on a small exclusion fence on the structure inlet, but the Pond Leveler pipe installed through the fence will control the height of the dam. The Pond Leveler pipe intake requires a pool depth of at least 3 feet to be effective. If that depth is not tolerable, a Culvert Protective Fence may be a better option. The Fence and Pipe device has a 99% success rate and requires less than 1 hour of maintenance per year.
A Starter Dam is the simplest and easiest device to install to protect road culverts from beaver damming. They can be built with fencing, or natural materials such as rocks, or wooden posts and branches like a Beaver Dam Analog (BDA). By creating just the beginning of a dam 10 – 15 feet upstream of the road culvert, it encourages the beaver to dam on it rather than on the culvert. This keeps the culvert undammed. It is used where ponding upstream of the road is tolerable and the goal is solely to keep the road culvert clear. It is the most most wildlife and fish friendly flow device, and is nearly maintenance free.
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Easy to follow Flow Device Installation Guide
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