LTPBR

(Low Tech Process-Based Restoration)

Self-Sustaining Systems

Instead of tackling restoration with expensive, reconstructive surgery done with heavy equipment and grading to make the channel look like we want it to, we encourage and allow the river to shape itself through improving its diet and exercise. PBR-LT is process based restoration – low tech. We think of our treatments as meals to the river (typically providing more structure like wood and beaver dams) and designed to kick off the process of recovery. Ultimately, we don’t want to be in the business of feeding meals to systems and want to encourage the processes that allow a system to feed itself. 

Increasing Riverscape Complexity

The vast majority of our streams and rivers have been starved of naturally occuring structural elements like woody debris and beaver dams. Starting with impacts like beaver over-trapping and extirpation, moving to logging, over-grazing, channel simplification, and debris removal, we have systematically simplified our systems to the point that the resulting habitats are so homogeneous that most native species don't have the diverse niches they once thrived in.

Simply feeding more structure to streams in a somewhat haphazard way will, in many cases, give the river the meal(s) it needs to build better habitat with time. However, in many cases, you can achieve  more specific habitat goals in the short and medium term with a higher degree of success, through strategic placement of the above 'structural solutions'.  Structural complexity within active channels increase the changes of a leveled plane that reconnects the channel to the floodplain. When this occurs, benefits include a restored and diverse riparian habitat, an increase in the water table, a higher rate of water retention, and an environment more adept at handling stressors such as flooding and wildfire.

Structure Types

  • BDA (Beaver Dam Analog)

    A man-made structure designed to mimic the form and function of a natural beaver dam. BDAs can also be used to increase the probability of successful beaver translocation by creating immediate deep water habitat that reduces the risk of predation. In general, the design and installation of BDA complexes is a simple, cost-effective, non-intrusive approach to stream restoration that can influence a suite of hydraulic, geomorphic and hydrologic processes in order to achieve a range of common restoration goals.

  • PALS (Post-Assisted Log Structure)

    PALS are permeable, temporary complexes used in structurally-starved riverscapes to create complexity in water flow and potential habitat for fish and wildlife. To stick around, the stacked wood is held in place by untreated wooden posts driven into substrate with a post-pounder. Both PALS and BDAS, in a project setting, are built in high quantities to achieve long term, restoration goals. ⁠

    Unlike BDAS, PALS are built without fill materials, such as sediment and herbaceous material. Woody material is solely used in their construction and is often wider in diameter. The main goal for PALS is to mimic the natural accumulation of large, woody debris and they are often used in tandem with BDAs to create as much structure as possible. They tend to take less time to complete as creation doesn’t involve the movement and layering of other materials. ⁠

Beaver as Restoration Planners

Considering that our design and construction process relies heavily on the use of beaver dam analogs, it must come as no surprise that our restoration efforts are inspired primarily by the work of the original river engineers, beaver. Beaver have wide impacts on the environment around them due to the influence of in-stream complexes created by beaver as lodges and dams to increase their habitat and safety from predators. The ponds that are created from beaver complexes increase surface water retention and groundwater recharge as well as create deep water habitat for aquatic species critical to ecological success. Because of their wood-cutting finesse, beaver also shape the riparian space around them. They effectively manage and control the local vegetation while contributing to its growth and complexity by providing higher water levels and a diverse level of aquatic species to enrich the area. As research grows, it has also been found that beaver meadows act as wildfire buffers which becomes increasingly more important in the face of powerful western wildfires of the present and future.

Anabranch not only is inspired by beaver but works with them, encouraging their proliferation during construction and monitoring with the priority being to set restoration in motion so that beaver and the river can continue the process over time.

Contact us with any beaver-related issues or relocation inquiries! Our goal is to mitigate beaver-human conflict as much as possible to encourage peaceful co-existence. Click below for more info on upcoming, beaver-related projects!

Floods as Restoration Agents

After centuries of failed attempts at 'flood control', it is now widely recognized that 'flooding' is needed to maintain healthy floodplains, riparian ecosystems and instream habitats. Much of the 'structural starvation' of wood and beaver dams, was done in the name of flood control. Removing obstructions to flow to increase conveyance during floods,  has made many streams far more efficient drainage courses. This also increases stream power and incision that could further the damage of intense floods in the future. floods are now widely recognized as critical and necessary disturbance agents in creating and maintaining complex and high quality habitat.