Restoring streams, floodplains, and wetlands doesn’t always require heavy machinery. Sometimes, simple, nature-based solutions are the most effective. That’s the idea behind low-tech process-based restoration (LTPBR)—an approach that uses natural materials and processes to support ecosystem recovery.
Two widely used techniques involve building simple, hand-crafted structures inspired by nature: Beaver Dam Analogues (BDAs) and Post-Assisted Log Structures (PALS). Both can help slow water, raise the water table, reconnect floodplains, and create the conditions for wetlands to return and streams to thrive.
Through the B.C. Wildlife Federation’s 10,000 Wetlands Project, Jennifer Rogers leads our restoration team in applying these techniques on the ground. In 2024, her team and project partners built 71 BDAs and one PALS across seven sites. Now, with dozens more structures planned and growing momentum behind our Beaver-Based Restoration work, we asked Jennifer to explain what BDAs are, how they work, and why they matter.
Q&A with Jennifer Rogers
Q: What are Beaver Dam Analogues (BDAs)?
BDAs are human-made structures that mimic dams built by beavers. They are typically constructed using local materials like mud, sticks, branches, and rocks, which are layered, woven together, and sometimes reinforced with untreated wooden posts to provide additional stability. The design elements of BDAs are taken straight from natural beaver dams, with a gradual ramp of sediment on the front face of the dam and a skirt of branches on the back side of the dam.
These low-tech methods are designed to harness the power of natural river processes, allowing naturally occurring materials such as sediment, vegetation, and woody debris to gather and restore the stream system over time.
Q: Why are BDAs important for ecosystem restoration?
Beaver dams play a key role in watershed health across North America as they create rich, diverse habitats by storing water and slowly releasing it downstream. The structures enhance habitat complexity, boost nutrient cycling, improve water quality, and support a wide range of wildlife species. Beaver dams also help maintain the connection between streams and their floodplains, which replenishes groundwater and strengthens ecosystem resilience against drought, wildfires, and flooding.
BDAs are a temporary solution to try and mimic some of the amazing benefits of natural beaver dams to help get the ecosystem back on a recovery path – and hopefully to set the stage for beavers to take over!
Q: Why can’t beavers do the work?
Ideally, beavers would build the dams, but in many areas where restoration work is needed most, streams are too degraded in their current state to support beaver populations. In these areas, restoration work like building BDAs and planting riparian plants such as willows and shrubs can kickstart the recovery process and make the habitat more enticing for beavers to naturally colonize, or for translocated beavers. Most low-tech process-based restoration projects aim to be self-sustaining, and this is best achieved when beavers are attracted to the stream to improve BDAs, build new dams, and expand the scale of restoration across the watershed.
Q: How do BDAs impact fish?
By slowing down water flow, forming pools, and activating side channels, BDAs create and enhance diverse habitats for many species, including native salmon and trout. Ponds formed by dams can act as important overwintering habitat and great feeding grounds for young fish. These ponds offer refuge during low-water periods, help regulate water temperature, and support nutrient cycling, which enriches the food supply for fish. Often beaver dams or BDAs reconnect fragmented stream systems, allowing fish to access critical spawning and rearing habitats.
Q: How long do BDAs last, and do they require maintenance?
BDAs are dynamic and will degrade over time though natural processes but continue to provide valuable services. When they are present, beavers can maintain the structures with minimal human intervention. Without beavers, seasonal maintenance is needed to reinforce the structures, patch any breaches that have formed and ensure they function as designed. BDAs can last from one year to over a decade, depending on a variety of factors including the flow regime, substrate type, placement within the system, and the presence of beavers.
Q: What are the long-term goals of the 10,000 Wetlands project?
The BCWF aims to improve the accessibility of low-tech process-based restoration to conservation groups and communities across the province. By navigating the permitting framework and studying the impacts of these projects, BCWF hopes to promote understanding, acceptance and excitement around process-based restoration.
By fostering a community of practitioners to learn from and collaborate with each other on these projects, the BCWF hopes to encourage the use of low-tech restoration techniques across the province. By supporting each other and sharing knowledge, the scale and impact of restoration will reach much further than the footprint of individual projects.
This story, by Jamie Long (Conservation Stewardship Communications Coordinator), first appeared in the JAN/FEB 2025 issue of BC Outdoors Magazine in our member exclusive insert. Become a BCWF member today to get our news delivered directly to your mail box at bcwf.bc.ca/membership.
BCWF Watershed Team 
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