Please visit these links for more detailed information regarding beavers and the construction of flow devices.
Working with Beaver for Better Habitat Naturally by Sherri Tippie
This guide, available online (pdf), includes information on ecological benefits of beaver as well as construction of flow devices and protection of trees and other property.
The Best Beaver Management Practices: Long Term Solutions to Beaver Dam Flooding by Beaver Solutions, LLC
This DVD details construction of flow devices for property owners. Available for purchase at Beaver Solutions.