Find out more about the Dias Ridge restoration and the effect of trail improvements on creek health at the Parks Conservancy's projects pages.
Previously, hikers used an old ranch road, eroding the surrounding area and depositing sediment into Redwood Creek. 1.2 miles of trail have been returned to natural conditions by filling eroded gullies and controlling invasive species. To replace the old alignment, crews built 1.5 miles of new, multi-use trial that will form a key connector in the Bay Area Ridge Trail.
The Redwood Creek watershed encompasses a breathtaking swath of habitat bordered by the peak of Mount Tamalpais to the north and extending south to Muir Beach where the creek empties into the Pacific Ocean. It also provides crucial habitat for a number of protected species under the Endangered Species Act including Coho salmon, steelhead trout, and the northern spotted owl. A good chunk of the watershed is within the boundary of Muir Woods National Monument, a very popular old growth coast redwoods forest that averages over one million guests per year. As with many National Parks, it is a balancing act between providing for the enjoyment and protection of these resources.
Redwood Creek is the southernmost range of Coho salmon, an amazing fish species that journeys from the oceans and back to the streams and rivers of their birth. This epic adventure begins as the sand bar at Muir Beach is breached by floods from the winter rains. Mature salmon fight their way upstream over log jams and through shallow spots to find a gravel bed near a nice deep pool. They do not eat at all during their voyage, and they die as soon as they have mated. All of this work is so they can successfully lay the eggs of the next generation. The salmon are very picky and can only make their nests, or reds, in areas where there is the right size of rocks and not too much silt, where the water is moving and not stagnant. After the eggs hatch, salmon need deep pools that remain aerated and cool throughout the summer for the juvenile salmon. Then as the winter rains begin, the juveniles need functioning floodplains and backwaters in order to escape the high water flows. Throughout their range in the Pacific Northwest, salmon habitat has been degraded through deforestation, unsustainable agriculture uses, and road building. There are very few places where an entire watershed is protected like at Redwood Creek.
The Human History of the Redwood Creek Watershed
Redwood Creek was within the boundaries of the Mission San Rafael, and extensive use began after the Mexican government took control and deeded the land to individuals. William Richardson bought parts of the Marin peninsula and began grazing Longhorn cattle on what he named Rancho Sausalito. Richardson also began logging the redwoods from the east side of Mount Tamalpais, and Portuguese dairy farmers moved into the region. The Banducci family moved to a site along the banks of Redwood Creek in 1850, and began growing flowers for the cut flower trade, mainly bulbs such as gladiolas. In order to avoid the flooding of their fields during the rainy season, the Banducci family installed dikes against the stream bank and channelized it, causing the water to flow fast and straight through that stretch, previously known as "the bowling alley."
Restoring the Banducci Site
The Park Service purchased the flower farm in 1986, and the restoration of the site began in 2003. First the dikes were removed in order to restore the historic floodplain. Then invasive vegetation such as cape ivy and Eucalyptus trees were removed. On a few big construction days in 2004, log jams and weirs were placed in the streambed to create deep pools as refuge for the juvenile salmon, and to restore the natural meandering bends in the creek. During this process, all of the water actually had to be removed, and any juvenile salmon in the creek were caught and moved further up or down stream. In 2007, the second phase of construction continued with more woody debris installation, and the creation of a frog pond as potential red-legged frog habitat onsite.
Other project designs included willow mattressing and bundles along creek banks as a living barrier to erosion, and lots of native plantings! Willows, alders, and other creek trees such as dogwoods and myrtles were planted to provide shade over the water. Thousands of fruiting shrubs, ferns, and wildflowers were planted to add food and cover for birds such as the Wilson's warbler and small mammals such as the dusky-footed wood rat. Flooding downstream has been reduced, and salmon numbers are up. The Banducci project is a testament to the fact that restoring ecological processes and allowing nature to take its course improves the habitat not only for the Coho salmon, but for all of the creek creatures that depend on a healthy watershed.
Last updated: February 28, 2015