As sea-level rise threatens Marin’s shorelines, the county is searching for nature-based solutions. A promising set of projects known as living shorelines could soon fortify the shores of Tomales Bay, protecting habitats and businesses from floods and improving public access to the water. In a study announced this week, the county’s Community Development Agency identified two spots on the bay, Cypress Grove in Marshall and Martinelli Park in Inverness, as potential sites for living shoreline measures, which would include altering streamflows, planting eelgrass and constructing small offshore islands from sediment or driftwood. “Living shoreline projects like these create a pathway to preserving both the vulnerable infrastructure and the natural value of the shoreline,” project engineer Dane Behrens said in a county press release. The projects, which harness nature to protect against a few feet of sea-level rise, would be more adaptable and less disruptive to habitat than traditional methods, but wouldn’t last as long. “Typically, hard shoreline structures like seawalls have negative impacts,” Leslie Lacko, a planner in the C.D.A.’s long-range planning division, told the Light. “They create erosion and you also lose habitat with them. We wanted to look at ways to protect the shoreline without putting in those structures.” The Tomales Bay Living Shoreline Feasibility Project, part of the county’s C-SMART sea-level rise response program, was funded by the California Coastal Conservancy, which also funded a study of sand dunes to protect beachfront properties in Stinson Beach last year. Two living shoreline projects exist along the San Francisco Bay near San Rafael and Richardson Bay, but these would be the first in West Marin. Cypress Grove, which is owned by Audubon Canyon Ranch, was identified by the Greater Farallones National Marine Sanctuary in 2019 as a potential site for native oyster restoration, which, along with other ecological benefits, could help protect against rising seas. Oyster reefs form hard natural barriers that grow over time, block waves and protect against erosion. County planners hoped to build on that potential by exploring a more extensive living shoreline project there, which could also help protect Audubon Canyon Ranch’s century-old bayside buildings from future flooding. The nonprofit had considered moving the building away from the shoreline, but a new beach berm, revegetation and a series of tombolos—small sand or driftwood islands that attenuate waves—could make that unnecessary. The report estimated the cost of the project somewhere between $1.2 million and $2.7 million. Martinelli Park, a part-public, part-private marshy area on the bay in downtown Inverness, is home to the much-photographed derelict  fishing boat, the Point Reyes. In its report, the county found that a horizontal levee and stream alterations to First Valley Creek would help protect nearby infrastructure that is vulnerable to rising water during storms and king tides, including the Inverness Store, the bus stop used by Marin Transit and Sir Francis Drake Boulevard. “The road in this location dips to an elevation of about 8.5 feet, which places it below the existing 100-year recurrence coastal flood level,” the county’s report states. “With sea-level rise, this would become a more frequent event.” The project could also promote public access to the boat and the bay. The uneven, ad hoc earthen berms around the Inverness Store parking lot are easily breached by floodwaters, as they were during the October storm and more severely in 2006. The study found that a deeper hydrological analysis of the flood-prone First Valley Creek would be necessary before beginning a living shoreline project, which would cost an estimated $672,000 to $1.4 million. The project could protect against 1.6 feet of sea-level rise, but any further rise would necessitate raising Sir Francis Drake Boulevard itself, the report found. Cypress Point and Martinelli Park would function as pilot projects for future living shorelines elsewhere on the bay. The county will host a public meeting on the conceptual designs at 5 p.m. next Monday, Jan. 24. Details can be found at MarinSLR.org.