Beaver Restoration

​​Process-based restoration seeks to return rivers to their natural state of complexity and connectedness to floodplains. Low-tech, process-based (LTPB) river restoration is the practice of adding simple, low unit-cost, structural additions--locally sourced rock, human-created Beaver Dam Analogs (BDAs), and anchored log structures--to riverscapes to mimic functions and promote specific processes.

Beaver-related restoration is a type of process-based restoration that seeks to re-establish dam building in degraded streams by relocating beavers to streams where dams are desired, building BDAs, or restoring riparian vegetation to attract beavers. It could be as simple as installing flow devices to manage beaver conflicts and keep beavers on the watershed, planting willows and other desirable vegetation on rivers in need of restoration to attract beavers, or actual relocation of beavers to a specific site.

Once BDAs are installed, they begin to slow the flow of the water and sediment can settle out. The sediment helps to raise the streambed. In some locations, BDAs can force water to move laterally into the floodplain, connecting the stream to the floodplain, recharging the groundwater, and allowing wetland vegetation to start growing in a wider corridor. Ultimately, a complex river-wetland corridor develops that filters out nutrients, sequesters carbon, increases floodwater storage capacity, and provides habitat for fish, birds, amphibians, and mammals. This is spread out over multiple years and is guided by the ongoing changes in the system. 

Conventional river restoration is form-based construction; it imposes a predetermined design on the stream. LTPB restoration costs about 20% of conventional restoration, according to Kevin Swift of the California firm Swift Water Design. “Form-based construction runs around $250k/mile of stream built, and our average is less than 20% of that cost per mile after 18 projects and 700 structures built.” In other words, up to five times as much river could be restored for the same amount of dollars using LTPB restoration. Process-based restoration is efficient and scales up easily.

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Process-based restoration creates more jobs than any other restoration method by focusing on handwork and human power. Instead of one guy operating heavy equipment, a process-based restoration job calls for a bunch of people with shovels. That means the carbon footprint is much smaller as well.

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