Across the Pacific Northwest, forests capture and store water. In healthy forests, diverse tree canopies slow the rain as it reaches the ground. Then it seeps through layers of moss, duff, and soil before trickling into small streams that gather and weave a complex river system across the landscape.
Before settlers moved west across the United States, these streams and rivers were full of wood. Fallen trees are a natural part of forest cycles of growth, death, and renewal. When settlers arrived, they cleared rivers to make way for boats and barges that carried goods and timber. Logs from upper watersheds were floated downstream to mills, often located where rivers slow and widen.
This removal of wood helped shape the Oregon we know today, but it also obscured our expectation of what rivers look like and how they function. Today, clear waterways can make recreation safer for boaters and anglers. But removing wood has made rivers less suitable for some native species, including beaver, trout, steelhead, and salmon.
Now, restoration practitioners across the state are thoughtfully working to return wood to rivers, especially in areas where salmon spawn. After decades of restoration work, some native fish populations are beginning to stabilize, but there is still more to do. In recent years, restoration has evolved to emphasize natural processes. In a river setting, this means broadly reconnecting rivers to their floodplains and adding more wood back into streams than people may be used to seeing.
Why do you use large wood in river restoration projects?
Large wood is a natural and important part of river ecosystems. It helps create habitat for fish and wildlife. When water flows around logs, it carves pools on the downstream side. These pools are deeper, cooler, and slower-moving—ideal conditions for fish.
Wood also shapes how water moves. It helps form riffles and seams, which sort and move gravel and sediment. Along riverbanks, wood provides shelter for animals like young turtles, which stay close to their nesting areas during their early years.
Wood also plays a role during storms. It slows down fast-moving water, spreading it out and reducing its force. This gives water more time to soak into the ground and allows sediment to settle.
Where does this wood come from?
Most of the wood used in restoration projects comes from public lands managed by partners such as the USDA Forest Service and the Bureau of Land Management. Unlike commercial timber, these projects often use whole logs with root wads still attached. These rootwad logs serve as anchors to capture additional wood and sediment. Additional cut-end logs are also used in these projects. When being placed, this wood is manipulated by an excavator to round out the ends and increase friction with the water. This helps restoration teams tell the difference between placed wood and wood that naturally enters the river, and helps slow down water more effectively than a traditionally felled tree.
How do you keep wood in a project area?
In-stream restoration projects are carefully designed and engineered. They go through years of planning and must meet strict regulations before work begins.
In each log jam placed in a project, some logs are anchored by burying part of the tree deep into the riverbed—often about 60% of its length. From the surface, you may only see a small portion of the wood. These anchored logs help hold other wood in place, including material that comes from non-restoration areas upstream. A certain amount of additional wood is carefully placed amongst these bed-anchored pieces. Some of this wood is placed to remain structurally in place, while other pieces are intended to move around a project area. Within each project, every logjam is thoughtfully designed to allow natural processes to function while also preventing wood from moving out of a project area.
Even with careful planning, rivers are always changing. We cannot predict every outcome. That’s why scientists monitor these projects over time. So far, monitoring in recent projects shows that most wood remains where intended and behaves as expected. This ongoing learning helps improve future projects.
What do you do if wood moves out of a project area?
Balancing nature’s needs and our need for nature requires flexibility. If wood from a project moves into a place where people boat or fish, restoration teams work with qualified partners to assess the situation.
In many cases, wood along riverbanks or on islands does not pose a safety risk and can remain in place, where it continues to benefit fish and wildlife. If wood poses a navigation hazard, trained crews can safely remove it.
I have more questions. Who can I talk to?
Many organizations work together on river restoration in western Oregon. If you’re not sure who manages a project, your local Watershed Council is a good place to start. They can help connect you with the right people and information. You can find your local Council using this online map.
