First Phase of Salmon Habitat Enhancement Project Underway in Muir Woods

Biologists have relocated fish north of Bridge 3 in Redwood Creek to different areas of the creek where they will not be impacted by upcoming habitat restoration activities.

NPS / Alison Taggart-Barone

August 2019 - This month, a project began in Muir Woods that aims to address one of the biggest threats to the survival of endangered coho salmon in Redwood Creek: the lack of good stream habitat for young fish.

Young coho need bending creek channels that slow down the water so they don’t get swept away during storms. They also need things like deep pools and fallen log jams where they can find food and shelter, especially during the hot, dry summer months. But Redwood Creek, where it flows through Muir Woods, does not offer these protections. Rather, 60% of its banks are lined with rocks and boulders, known as riprap, installed by the Civilian Conservation Corps in the 1930s. As a result, it is mostly straight, shallow, and clear of large debris. This altered habitat continues to take a toll. According to more than 15 years of monitoring, young coho that hatch from redds (nests) in the section of the creek that flows through Muir Woods are less likely to survive than their downstream counterparts.

To improve the coho habitat in Redwood Creek, the Redwood Creek Salmon Habitat Enhancement Project will remove large sections of riprap from the creek bank, reconstruct a more meandering creek channel, and add some fallen logs from the forest nearby. The aging bridges over the creek will also be replaced with new ones that will accommodate a more natural creek channel. The work will take place each year for three years between the months of June and January to avoid disrupting coho and steelhead spawning and northern spotted owl breeding in the park.

This year’s work is taking place upstream of Bridge 3. Already, biologists have relocated fish to safe sections of the creek. In addition, the creek’s flow is being rerouted around the restoration area with screened pumps. That way, the heavy equipment needed to remove riprap won’t injure wildlife or muddy the waters for those that live downstream. Once the riprap is removed and the stream channel has been re-graded, erosion control will be installed, the creek will be rewatered, and native plants will be planted along the banks. This year’s work should wrap up in October, although monitoring of the site’s recovery will be ongoing. The bridge replacements will take place next year.

Learn more about the Salmon Habitat Enhancement Project and other Redwood Renewal projects taking place in Muir Woods, or contact Mia Monroe with any questions.

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