Posted on November 5, 2025
Our Goals
Restore and expand the mixed sand-gravel beaches and salt marsh along Greenwood Beach with enhanced resilience to erosion and shoreline retreat.
What We’re Doing
Audubon California and partners are constructing a living shoreline to demonstrate the effectiveness of gravel and sand beaches as an alternative to rip-rap shorelines to inhibit wind-wave shoreline erosion.
Situated along the northern shoreline of Richardson Bay, Greenwood Beach is facing habitat loss due to wind-wave shoreline erosion and the degradation of an emergent marsh. Audubon California, in partnership with the Town of Tiburon, the County of Marin, Gillenwater Consulting, as well as other restoration experts, is working to restore this ecosystem- enhancing habitat for shorebirds and other wildlife while ensuring long-term resilience using nature based solutions.
This project aims to demonstrate how the effectiveness of gravel and sand beaches as an living shoreline based alternative to rip-rap shorelines in order to inhibit wind-wave shoreline erosion.
Paige Fernandez, San Francisco Bay Program Manager, performing a beach boulder size analysis.
Project Overview
The Greenwood Beach Restoration Project (the project) is a nature-based beach restoration and shoreline erosion protection project proposed on approximately 1.4 acres of the Richardson Bay shoreline at Blackie’s Pasture Park in Tiburon, California. This project employs a “living shorelines” approach to address ongoing shoreline erosion and habitat degradation at the site, meaning that it addresses these issues utilizing techniques and materials that take advantage of natural processes and provide nature-based shore structure and for natural habitat-forming processes, while maintaining and enhancing existing public uses of the shoreline. The specific project design objectives include:
- Restore and expand the mixed sand-gravel beaches and salt marsh along the shoreline with enhanced resilience to erosion and shoreline retreat.
- Use locally sourced sediments and/or beneficially reuse off-site “waste” sediments for beach restoration and enhancement to the extent feasible.
- Restore native backshore and salt marsh vegetation and habitats that can migrate sustainably landward with retreating shorelines as sea level rises.
- Pre-empt the need for typical “emergency” shoreline erosion response of rip-rap placement, which would make beach loss more permanent and degrade the scenic, recreational, and habitat values of the shoreline.
- Demonstrate the applicability of restoring bay beaches as a feasible alternative to traditional rip-rap shoreline stabilization to inhibit shoreline erosion while providing habitat and public access values.
The beach restoration approach combines beach nourishment with related wetland and terrestrial elements, including regraded shoreline scarps stabilized with native sand-trapping beach vegetation, large woody debris, and low-relief “drift-sills” (perpendicular to the shore) composed of cobble salt marsh. A rendering of the design elements and proposed site conditions approximately 3 years after construction is provided below. Project implementation is funded by a grant from the State Coastal Conservancy and construction is scheduled to begin in Fall 2026.
Project Design for the Greenwood Beach Restoration Project. Photo: Gillenwater Consulting
Pilot Scale Design Test – Fall 2025
The project design includes a novel approach to beach sediment retention and habitat enhancement – the cobble salt marsh drift-sill. These sills are designed to provide groin-like living shoreline functions capable of accreting and maintaining sand-trapping high salt marsh vegetation. Their primary purpose, like that of beach groins, is to restrict longshore drift of sand, but they also act as vegetated beach ridges that accrete sediment by vegetative sand trapping and stabilization while resisting wave erosion with a layer of cobble armoring.
Given the novel nature of the drift-sill design, the project team will be constructing a pilot-scale drift-sill at the site in November 2025 to resolve questions around construction methods and short-term sill stability, which will inform the final design of the project. The pilot drift-sill will be a scale model of the proposed sill design and will be built within the footprint of the sill that will be constructed in Fall of 2026. The pilot sill will be monitored over the course of the winter to understand stability and function under both storm and calm weather conditions.
We respectfully ask for cooperation from the public during the monitoring period this winter to maximize the information obtained from this pilot project. Please do not intentionally walk on or damage the sill or the small wedge of beach material adjacent to it.
For more information on this project, please contact David Eshoo with the Town of Tiburon- deshoo@townoftiburon.org– or Roger Leventhal with the County of Marin- roger.leventhal@marincounty.gov.
