The Contra Costa County Water Conservation and Flood Control District constructed the Lower Walnut Creek Restoration Project to restore and enhance coastal wetlands and adjacent habitats at the mouth of Walnut Creek, providing flood protection while also improving habitat quality, diversity, and connectivity along the creek channel. The project is located along the southern shoreline of Suisun Bay, east of Martinez in Contra Costa County, California. Restoration has been accomplished by breaching and lowering levees, berms, and uplands to reintroduce tidal connections to diked Baylands, constructing setback levees for flood protection, new tidal channels, tidal wetland, and adjacent lowland and upland terrestrial habitats. Construction activities occurred from 2021 to 2022. Regional ecosystem goals called for restoration of this habitat matrix and noted that opportunities for its creation are rare around San Francisco Bay’s mostly developed shoreline. These habitats provide increased diversity and enhanced ecosystem functions under present day conditions and will sustainably evolve with future sea level rise. Environmental Science Associates conducted protocol-level surveys for endangered California Ridgway’s rail and threatened California black rail from 2019-2025. ESA documented California black rails colonizing restored marshes 2 years after construction, highlighting the importance of restoring minimally subsided baylands for rapid recovery.