The trampled and eroded soils of the San Geronimo Valley’s most popular old-growth redwood grove have diminished the resiliency of the forest. Now, a major restoration of the Roy’s Redwoods Open Space Preserve will decommission the vast network of informal trails in the 300-acre preserve and reconnect Upper Larsen Creek to its floodplain, restoring the area’s ecology and hydrology. A draft Initial Study/Mitigated Negative Declaration for the project, released last week by the Marin County Open Space District, determined that, with proper mitigation measures, the preserve’s environmentally sensitive areas—including endangered spotted owl habitat—would not be significantly impacted. The project is being undertaken by One Tam in collaboration with Marin County Parks and the Golden Gate National Parks Conservancy. “It’s exciting because that particular reserve has been loved to death,” said Jon Campo, the county’s principal natural resource planner. “This is one of the bigger efforts [Marin] County Parks has entered into.” Restoring the health of the forest includes opening areas where compacted soils have suffocated the earth. Using picks and spades to make the forest’s floor spongy and permeable will promote growth and facilitate a revegetation of the understory with thousands of native plants. Creating bridges and boardwalks will keep visitors on trails and bolster the project’s lasting impact. The project will reconnect the creek to the floodplain by adding large logs to create a network of channels that will slow down and trap waters, recharging the local aquifer; this will saturate the ground, rejuvenate tree roots and add to the forest’s resilience to drought. Currently, around 6,500 feet of informal trails run through the preserve’s old-growth redwoods and sensitive habitat areas. Decommissioning those trails with new fencing and visitor information signs will make the forest more discernible for travelers and promote a healthier ecosystem. “If you go out to the old-growth grove, having never been there, you really wouldn’t know where to go. You’d just kind of stumble around not knowing where to go,” Mr. Campo said. Around 5,670 feet of existing trails will be realigned to improve drainage and prevent erosion and sedimentation, and around 2,000 feet will be upgraded to meet Marin County Parks’ Inclusive Access Plan standards. Since Upper Larsen is an ephemeral creek, it is not inhabited by coho or other anadromous fish. But there is another endangered species in the preserve: the northern spotted owl. The open space district determined that the project would not impact the birds’ nesting behavior. The district will present the project’s mitigation strategies at a future board meeting. As a part of improving access to the preserve, the county will develop two new designated entryways to replace the current entrance at Nicasio Valley Road, install one handicapped parking spot on the shoulder and relocate the porta-potty out of the floodplain. The preserve, which the county purchased in 1978, is a staple of valley education. For years, the Lagunitas Middle School students have hiked to the grove—where George Lucas filmed scenes from his 1984 movie, “Caravan of Courage: An Ewok Adventure”—for their physical education classes, and students engage in curriculum there. Implementing the restoration project is expected to cost $2.9 million. Marin County Parks has already acquired $2 million in funding, including from the California State Park’s Regional Parks Program and the county’s office of accessibility. Mr. Campo said the agency will apply for more funding and that he expects philanthropic support from members of One Tam. The project documents can be found by visiting www.parks.marincounty.org/projectplans and clicking on “Redwoods Restoration.” Comments can be submitted through March 10.