Building a Beaver Deceiver
Beaver Conflicts
| Introduction
Building a Beaver Deceiver
|
The trash rack protecting the outlet control structure is being dammed by beavers.
(Click on photo for full screen version)
Additional beaver activity at the facility.
(Click on photo for full screen version)
Since construction of the facility, the trash rack protecting the outlet control structure has been dammed repeatedly by beavers. Maintenance crews had not been able to keep the outlet clear. The submerged bypass pipe had also become plugged. This blocked any possible fish passage and caused water to back up in the pond to close to the point of overflow. King County received notification from the Washington State Department of Fish and Wildlife (WSFWS) and the Department of Ecology Dam Safety Office that the beaver dam needed to be removed.
The upstream end of the fish ladder/outlet control structure.
(Click on photo for full screen version)
Beaver dam at the trash rack showing woody debris and mud.
(Click on photo for full screen version)
While the Peterson Pond beavers had demonstrated their ongoing commitment to damming the pond outlet, the local residents strenuously objected to any removal or relocation of the beavers. In September 2000, the beaver dam was removed, and the submerged pipe was cleaned so as to function properly. Maintenance crews were instructed to monitor and remove any debris while Stormwater Services staff determined a long term solution that met the concerns of the Swan Lake Estates residents, Washington State agency staff, and also King County stormwater facility maintenance requirements. By Spring 2001, the persistent beavers were winning the battle and the outlet was again completely blocked.
During this time, the King County Wildlife Program was working with the Humane Society of the United States (HSUS) and Mr. Skip Lisle to sponsor the "Solving Conflicts with Beaver" workshop to be held in King County. Stormwater Services staff approached Dr. John Hadidian from HSUS and Mr. Lisle about the possibility of constructing a "beaver deceiver" facility at Peterson Pond. Mr. Lisle and Dr. Hadidian both agreed with enthusiasm that the "beaver deceiver" concept that Mr. Lisle had developed was appropriate for the Peterson Pond site.
Permits required for the project included a Hydraulic Project Approval (HPA) from the WSFWS and a Clearing and Grading permit from the King County Department of Development and Environmental Services. The residents of Swan Lake Estates were also notified and supported the project.
The "beaver deceiver" was constructed on August 10th, 2001. The following photos and text show the construction sequence in chronological order. Outflow from the pond ceased shortly after construction so that the beavers are less attracted to the outlet, therefore it will not be possible to determine the success of the beaver deceiver until flows resume in the next several weeks.
King County will monitor the facility to ensure the structure functions as intended. Additional photos will be posted in future months documenting how the beavers react to the new "beaver deceiver" at the Peterson Pond outlet.
Next Page: Construction Sequence
Top of this page |
