Beaver pipe
Beaver Pipes used to control water levels in Hunt Marsh, Mecosta County, Michigan. These pipes divert water downstream while allowing beavers to continue to build their dams to whatever size they choose. This photo shows beaver pipes constructed at Enzo Creek Nature Sanctuary, a private nature sanctuary near Big Rapids, Michigan.
Beaver Pipes are a non-destructive flow devices, a way of controlling beaver activity in an ecosystem. The process of building beaver pipes is quite simple, and often serves as a permanent way to prevent beavers from damming water.
Enzo Creek Nature Sanctuary
Managers of the watershed of the Enzo Creek Nature Sanctuary experienced the all too common problem with beavers: their tenacious desire to dam water. The water level at Enzo Creek Nature Sanctuary had been growing year after year, impacting the fauna in Hunt Marsh, an 18-acre (73,000 m2) wetland which serves as both a waterfowl nesting area and refuge. Managers physically removed the dams from Enzo Creek, the only outlet to the watershed; however, beavers would quickly work to rebuild them. Lethal removal of beavers from the marsh was contrary to the mission of the sanctuary, so the non-lethal method of beaver pipes was approved and adopted.
Overview
The construction of these beaver pipes at Enzo Creek Nature Sanctuary was a two-day project for one person. and involved the following steps:
1. Slowly lower the water level behind the dam. Physically cut a notch in the position on the dam where beaver pipes are to be installed. In this case, a shovel and pitchfork were used. It is important to note that this process may take a significant amount of time depending on the volume of water already in reserve behind the dam. In the case at Cielo, this dam controlled the water level in a very small pond and was drained to the desired level in about two days. It is suggested that prior to beginning this project, a marker be installed that shows the target water depth so installers know when the correct water depth has been achieved.
2. Insert pipes across the notch. In this case, as shown, the upstream pipes are made from 10-foot (3.0 m) sections of perforated 4" PVC pipe. The perforations allow water to enter the pipes. The upstream ends of the pipes have a 90 degree elbow pointing downward into the water, and are anchored to steel fence post supports at the upstream end of the pipes as well as in the notch. The perforated pipe is joined to non-perforated pipe at the notch, and then appropriate elbows are used to drop the pipes to the downstream position for water to exit. Threaded caps are placed on the final section, and then plugged with end caps. Steel fence post supports are used on the downstream portion as well to hold the pipes in position. Flexible galvanized wire is best to attache the pipes to the posts.
3. Beavers complete the project. With the downstream pipes capped, water will continue to run through the notch. As shown in the photo, beavers will quickly move to dam the flowing water over and around the pipes. As they do this, the water level will rise behind the pipes. After the beavers have a good seal established over and around the pipes, remove the end caps and the water level upstream will reach equilibrium with the level of the upstream pipes. Remember it is the sound of running water that will attract beavers to build a dam, so the further downstream you divert the water, the better.
References
- Beaver Damage Control and Management Information
- Beaver pipes and beaver deceivers for flood control
- http://www.fs.fed.us/r2/psicc/leadville/Beaver-Document.pdf
