COS 118-9 - Beavers in restoration ecology: Why we should give a dam!

Wednesday, August 9, 2017: 4:20 PM
B115, Oregon Convention Center
Penny E Hughes, Wapato Valley Mitigation and Conservation Bank, Ridgefield, WA

Beavers are increasingly considered in planning and design of aquatic habitat restoration efforts, including human built beaver-inspired habitat structures. The design team for the Wapato Valley Mitigation and Conservation Bank (Wapato Valley) looks to utilize these nature engineers while designing restoration and monitoring the restored conditions. Wapato Valley Bank is located on 876 acres of diverse floodplain habitats in the Columbia River Estuary that have been altered over the last 170 years to meet human needs. The planned mitigation actions will remove man-made constraints to habitat forming processes and restore the land back to pre-development conditions, while generating multi-resource mitigation credits. The restoration design team including a restoration ecologist and an engineer are interested in how habitat characteristics shaped by beaver contribute to habitat functions and how the design team could create similar complex habitat features to increase functions and encourage more beaver activity and habitat maintenance. The field crew used remote-sensor wildlife cameras, beaver structure inventory, soil cores, water surface elevation, and topographic and temperature measurements among other data collected in beaver channel networks to inform restoration design. These same parameters will be monitored during and after restoration construction for a minimum of 10 years.


Observations of the native beaver population have provided an abundant source of information to our restoration design. The channels within the floodplain wetlands mimic beaver channels in dimension and elevation such that they intercept ground water providing surface water during all but the driest summers. Additionally, this water is cooler than that of the surrounding bodies of water, and will support native juvenile fish, while hopefully deterring non-native fish. These channels appear stable, with the help of regular maintenance by beaver. We have seen with wildlife cameras that many species benefit from the channels and ponds created by beaver. Especially during low water, these areas are key locations for animals to find food and water when the vast majority of the floodplain is dry. Our restoration design encourages beaver dams and may utilize beaver dam analogs to encourage beaver activity in strategic locations. We have learned a great deal from extensive pre-project monitoring to help us create a low maintenance, process based restoration design that builds in resiliency in the face of climate change. We hope that our site encourages these natural engineers to assist in the ongoing stewardship of restored wetlands and aquatic habitats at Wapato Valley Mitigation Bank.