Reducing the height of a beaver dam is the most expedient strategy for alleviating an acute flood risk caused by the presence of a beaver dam. When lowering the level of a beaver dam, timing is extremely important because if done at the wrong time of year, beaver are likely to immediately repair or rebuild the dam.

The best way to "breach" or reduce the height of a beaver dam is to use hand tools such as four-pronged pitch forks, long-handled cultivator rakes (potato hooks), shovels, and/or chainsaws, to dislodge and remove material from the top of the dam until you've reduced the water levels to the desired height. Alternatively, mechanical equipment, such as backhoes or excavators, could be stationed at the top of the bank and used to scrape off layers of the dam; however, this process requires special equipment and skills and can result in habitat degradation or destabilization of the streambank if not done properly.

Important notes about beaver dam reduction:

• It is important to breach the dam gradually - releasing too much water quickly can cause problems downstream and impact fish and other aquatic life.

• Breaching a beaver dam may trigger beaver to rebuild, leading to additional vegetation removal by beaver for dam building materials. This sometimes pushes them further from the site or toward ornamental vegetation if sufficient native vegetation does not remain at the site.

• The best time to breach a beaver dam is in the fall when water levels are stabilized and beaver are less likely to rebuild.

• Full dam removal requires significant effort and will typically drain the entire beaver pond. This often exposes submerged den and burrow entrances, allowing access by terrestrial predators. If there are indications that beaver are active in the area, it is best to avoid dam removal during the kit season from April to June.

• Beaver dam reduction or removal may require a permit from the Oregon Department of State Lands or consultation with the Oregon Department of Fish and Wildlife, depending on the dam’s location. For example, in streams designated as Essential Salmonid Habitat, any amount of removal of material requires a permit from Department of State Lands.

Pond levelers are devices that allow beaver to continue maintaining a dam while keeping water levels behind the dam at a certain level during baseflow conditions and limiting the rise of the water during large storm events. Using this type of device minimizes disruption to the beaver colony, while confining the beaver pond to an acceptable footprint. This is accomplished by installing a large-diameter flexible pipe with a hidden intake through/over the dam to essentially create an irreparable leak. The beaver can't hear the leak, so they do not attempt to repair it.

Exclusionary fencing, also known as the "Beaver Deceiver", can be installed around the opening of a culvert or other constriction to keep beaver from plugging or blocking it. The main goal of exclusionary fencing is to keep beaver far enough away from the culvert to reduce the sound and feel of trickling water that triggers their desire to plug the hole.

Specific guidance for pond leveler construction, installation and maintenance are evolving. The most current guidance can be found in Chapter 9 of the Beaver Restoration Guidebook found on The Beaver Coalition's website. We recommend working with a specialist to design and install an appropriately sized device and ensure permitting requirements are met.

Important notes about pond levelers and exclusionary fencing:

• City, state, and/or federal permits may be required, depending on the location and configuration of the device. Consult with the City of Salem's Public Works Development Services office for guidance on City regulations pertaining to installation of a pond leveler in a floodway, the Oregon Department of State Lands Aquatic Resource Coordinator and Oregon Department of Fish and Wildlife (ODFW) for guidance on state regulations, and the Army Corps of Engineers for guidance on federal regulations.

• Because of the complicated regulatory environment surrounding installation of pond levelers, we recommend contacting ODFW, your local watershed council, an environmental consultant, or The Beaver Coalition for guidance before attempting to install one of these devices yourself.

• Pond levelers should be checked 3 - 4 times per year to ensure they remain functional and do not become barriers for fish passage.

• Once installed and properly maintained, they can be very long lasting.

• They should be removed from the stream as soon as they are no longer needed.

This has been a go to strategy for many in the past but is increasingly becoming recognized as a last resort and a temporary solution at best. Since beaver are highly territorial and their populations are increasing statewide, removing them from a suitable habitat will open that territory up for other beaver to inhabit, unless the habitat is modified. If the area is good beaver habitat, a new family will likely move into any territory that is opened up through beaver removal. Trapping and removing or relocating beaver can therefore become a costly treadmill of reactionary management, should only be used as a last resort when all other options for coexistence have been exhausted, and should always be paired with habitat or infrastructure modifications to prevent future conflict when new beaver inevitably arrive.

Important notes about beaver removal:

• If beaver need to be moved a very short distance (less than 1,000 feet), such as to get them out of or away from pipes or manholes before placing exclusionary devices, consider using hazing strategies rather than trapping.

• On private lands, the beaver is currently designated as a predatory animal (i.e., destructive to private property) under Oregon Revised Statute (ORS 610.002). A private landowner may trap and kill a nuisance beaver on their property. There is no approval necessary from ODFW if the landowner performs this task, and there are no reporting requirements. However, due to the challenges and risks posed by trapping, landowners are strongly encouraged to hire a Wildlife Control Operator (WCO) to perform this task. WCOs report their activities directly to ODFW.

• On public land, beaver are classified as protected furbearers under Oregon Administrative Rule (OAR) 635-050-0050 and Oregon Revised Statute (ORS) 496.004 and 498.158. If the City needs to trap or haze beaver on City of Salem property, we must contract with a WCO. In some cases, a permit or coordination with Oregon Department of Fish and Wildlife may be required.