Last updated: March 15, 2024
Article
Redwood Creek Salmon Habitat Enhancement Project
NPS / Jace Ritchey
Redwood Creek hasn't looked this natural in almost 100 years - what happened?
Redwood Renewal is a sweeping, multi-year effort to help protect the health of Muir Woods. The summer of 2023 was a particularly exciting time, as we repaired a century of damage to parts of Redwood Creek and recovered vital habitat for the endangered coho salmon that live here. Between July and November 2023, we removed a portion of the rock walls, or “riprap,” that lined the creek banks, and installed trees and logs in creek to create fish habitat. In 2019, we completed part of this work in the upstream half of Muir Woods. Over time, the natural movement of water will finish the job of transforming Redwood Creek from its current hardened state to a more complex, natural, and healthy stream ecosystem with lots of deep pools and cover for young coho salmon.
For the fish…
Decades of research have taught us that the biggest threat to the survival of Redwood Creek’s coho is a lack of good stream habitat for young fish. Part of the problem is that in the 1930s, some of the creek was lined with rock to stabilize its banks. Large swaths of the forest understory were also cleared to provide people with better views of the biggest trees, and fallen trees were removed if they fell in the creek. Since then, we have gained a better understanding of how streams and forests work. After turning the meandering stream into a straight channel, we learned that riprap in fact makes the water flow faster. Meanwhile, fish – especially young salmon – need bends, pools with slow flow, and logs with pile-ups of small branches in which to shelter and feed. While we used to value the big trees above all else, we are learning of the importance of balance in the ecosystem.
…and for the forest
Removing the rock walls will benefit not only coho, but also other plants and wildlife and even insects that depend upon a healthier stream and forest ecosystem. Slowing down the creek’s flow and creating still pools may help increase groundwater levels in the creek and nearby forest. This will be especially important during times of drought as our climate changes. This collaborative effort among agencies, nonprofits, youth corps, and volunteers will also help manage weeds and restore native plants.
Project Timeline
Work took place between July and November to limit disturbance to wildlife like nesting birds and spawning salmon. That means visitors who came before July 2023 or after November 2023 experienced a more typical Muir Woods forest. However, visitors to the woods between July and November 2023 witnessed restoration and science in action.
Because this project is happened in phases, you may see different things depending on when you are in the woods. There was heavy equipment working in the creek, but a long list of protections were employed to prevent injury to wildlife or trees. The heavy equipment was necessary to help undo actions that have been harmful to the creek and salmon habitat. The impacts of heavy equipment are temporary, but its benefits will be long-lasting. Coho and other aquatic life were collected and moved to another section of creek before each dewatering and work phase began.
Related Links and Resources
- Redwood Renewal coho salmon video
- Volunteer opportunities
-
National Park Service coho salmon monitoring in the San Francisco Bay Area and related 1-page handout
- Coho “jumpstart” project
Redwood Creek Salmon Habitat Enhancement Project FAQs
Learn more about this project in our Frequently Asked Questions below:
Restoring habitat for young endangered coho salmon in Redwood Creek is the park’s highest priority for helping this species survive here. Coho numbers along the central California coast are only at about 1% of historical levels. In Redwood Creek this species is near extinction.
Coho live in freshwater streams when they are young but spend their adult lives in the ocean, making them vulnerable to what happens in both places. Based on more than 15 years of data, we know that while adult coho return to Redwood Creek to spawn, the numbers of juveniles remain low. We also know that young salmon born in the part of the creek that passes through Muir Woods are much less likely to survive than those born farther downstream.
It seems that even more than what happens out at sea, coho here are struggling because young fish don’t have the habitats that they need to survive.
Redwood Creek in Muir Woods it is mostly flat and shallow, with almost no logs or other large woody debris. However, juvenile coho need deep pools and lots of logs and other cover to survive through the summer. So, we are removing some of the rock walls that line the creek and using fallen trees from the forest floor to create better fish habitat. Over time, the natural movement of water will finish the job of transforming Redwood Creek from its current hardened state to a more complex, natural, and healthy stream ecosystem that will provide a better home for many creatures, including coho salmon.
Coho live in freshwater streams when they are young but spend their adult lives in the ocean, making them vulnerable to what happens in both places. Based on more than 15 years of data, we know that while adult coho return to Redwood Creek to spawn, the numbers of juveniles remain low. We also know that young salmon born in the part of the creek that passes through Muir Woods are much less likely to survive than those born farther downstream.
It seems that even more than what happens out at sea, coho here are struggling because young fish don’t have the habitats that they need to survive.
Redwood Creek in Muir Woods it is mostly flat and shallow, with almost no logs or other large woody debris. However, juvenile coho need deep pools and lots of logs and other cover to survive through the summer. So, we are removing some of the rock walls that line the creek and using fallen trees from the forest floor to create better fish habitat. Over time, the natural movement of water will finish the job of transforming Redwood Creek from its current hardened state to a more complex, natural, and healthy stream ecosystem that will provide a better home for many creatures, including coho salmon.
Most visitors to Muir Woods probably do not notice the boulders and rocks that line over 60% of the creek’s banks. In the mid-1930s, the Civilian Conservation Corps (CCC) built many of the walls, stairs, and bridges that you see in Muir Woods today. Between 1934 and 1938—at a time when the National Park Service did not understand the dynamic nature of creeks—these crews hauled boulders from nearby Kent Canyon and installed them along some 3,300 feet of the creek to stabilize its banks and prevent erosion.
The walls create a straight stream channel with shallow water, which is not good juvenile coho salmon habitat. If the walls were not there, winter storm flows would create a more naturally meandering stream pattern and the deeper pools that the young fish need to survive.
Yes, they are. The walls were built by the CCC in the 1930s as part of New Deal programs to create jobs during the Great Depression. This project balances historic preservation with creating critical habitat for endangered coho salmon by leaving some walls in place, including in places where visitors can see them. The State Historic Preservation Office has approved the removal of all of the walls that are being taken out.
Heavy equipment is needed to remove the rock walls from the creek. However, not only would it be hard for this equipment to do its work in flowing water, having it in the water would also make downstream areas turbid and muddy. Therefore, the water must be removed from the project area before work can begin.
“Dewatering” the part of the creek where we are working will be done using a screened pump to keep fish or other animals from being pulled in. The water is then piped downstream to maintain streamflow around of the project area.
Trained staff will remove any fish or other wildlife from the project area before the water is removed. Nets extending across the creek will be used to divide the work zone into smaller areas to better capture the animals. They will be kept in cool, shaded, aerated, water-filled containers and protected from excessive noise, jostling, overcrowding, or predation until they are relocated to other parts of the stream.
“Dewatering” the part of the creek where we are working will be done using a screened pump to keep fish or other animals from being pulled in. The water is then piped downstream to maintain streamflow around of the project area.
Trained staff will remove any fish or other wildlife from the project area before the water is removed. Nets extending across the creek will be used to divide the work zone into smaller areas to better capture the animals. They will be kept in cool, shaded, aerated, water-filled containers and protected from excessive noise, jostling, overcrowding, or predation until they are relocated to other parts of the stream.
The National Park Service and Golden Gate National Parks Conservancy have undertaken a number of restoration projects to improve coho habitat in the Redwood Creek Watershed. Two of the most recent examples are the Coho Jumpstart Project and the restoration of Redwood Creek at Muir Beach.
Coho Jumpstart
There have been extensive efforts to restore Redwood Creek and its floodplain to improve conditions for young fish, especially the federally endangered coho salmon. But what happens to these young fish after they go out to sea—and before they come back to the stream to spawn—is beyond our control.
Since 2015, staff and volunteers have taken juvenile coho from Redwood Creek to be reared at the Don Clausen Fish Hatchery. Young fish raised in hatcheries have a much better survival rate than those that are out in the ocean. The fish are then released back into the creek as adult spawners. As of January 2019, a total of 459 spawners have been released.
The hope is that by boosting the number of young fish that survive to reproduce we can once again create a self-sustaining population of coho salmon in Redwood Creek.
The Restoration of Redwood Creek at Muir Beach
This multi-year, landscape-level restoration project brought back the ecological functions of the creek, floodplain, freshwater wetlands, intermittent tidal lagoon, and dunes where Redwood Creek meets the Pacific Ocean. It also created habitat for threatened and endangered species like coho salmon, steelhead trout, and California red-legged frogs.
About 1,700 linear feet of the creek now flows through its natural path across the restored floodplain. More than an acre of new sidewater areas also provide essential resting and feeding habitat for young salmon and steelhead.
We can only work between June and January to limit the effects on sensitive species like nesting northern spotted owls and spawning coho salmon. Because the construction season is limited, this project will take about three years to complete.
Keeping the woods open during construction means that the hundreds of thousands of visitors who flock to Muir Woods each year can still experience the magic of the redwood forest. Visitors that come during the construction season will also get to see how a national park is working to heal past damage, help endangered species, and preserve the beauty and inspiration of Muir Woods for generations of visitors to come.
Keeping the woods open during construction means that the hundreds of thousands of visitors who flock to Muir Woods each year can still experience the magic of the redwood forest. Visitors that come during the construction season will also get to see how a national park is working to heal past damage, help endangered species, and preserve the beauty and inspiration of Muir Woods for generations of visitors to come.
Access to the park will vary throughout the summer and fall project season, and could include closures, safety detours, and parking changes. However, there will always be opportunities to walk among the redwoods, take hikes of varying lengths, and participate in park programs. Consult the "alerts" section on www.nps.gov/muwo to both plan ahead and to learn more about current conditions.
Yes it is the same. However, every effort has been made to schedule projects to minimize their impact on park visitors.
While there may be closures or detours, visitors will have the truly unique experience of seeing science in action in a national park as we use what we have learned through years of monitoring to help the endangered coho salmon that live here. Returning visitors will also be able to witness the ongoing renewal of Muir Woods over the years to come.
While there may be closures or detours, visitors will have the truly unique experience of seeing science in action in a national park as we use what we have learned through years of monitoring to help the endangered coho salmon that live here. Returning visitors will also be able to witness the ongoing renewal of Muir Woods over the years to come.
Slowing down the creek’s flow, creating still pools, and reducing erosion will help increase groundwater levels. This will be especially important during times of drought as our climate changes. A less channelized and more naturally meandering stream with large logs in it will also help slow fast moving stormwater and will be better able to adapt to temporary flooding from storms.
We are being extremely careful about where we remove the rock walls, and we do not expect that this work will cause more trees to fall. In fact, removing the walls will allow the trees near the bank to develop buttress roots for better support.
Most trees in Muir Woods fall from the hillslopes and not near the creek. However, it is always possible that a tree will fall into the creek someday, as trees do naturally fall in a forest. And if it happens to land in the water, it will help create even more habitat for juvenile salmon!
Most trees in Muir Woods fall from the hillslopes and not near the creek. However, it is always possible that a tree will fall into the creek someday, as trees do naturally fall in a forest. And if it happens to land in the water, it will help create even more habitat for juvenile salmon!
This project is fully funded by visitor entrance fees. The current Federal Lands Recreation Enhancement Act (FLREA) allows the National Park Service to collect and retain revenue and requires that fee revenue is used to enhance visitor experience. For more information visit https://www.nps.gov/aboutus/fees-at-work.htm
This project underwent a thorough environmental review, including public comment periods. You can learn more about the review process and findings here.
For more information visit https://www.nps.gov/muwo/getinvolved/redwood-renewal-begins.htm