Priorities
San Mateo County has already been severely affected by the water-related impacts of climate change. It has experienced extreme storms, drought, and coastal erosion and flooding; and studies by several agencies and universities confirm that sea level rise threatens more people and property here than in any other county in California and in more than 90% of all U.S. coastal counties. Local residents and leaders recognize this transformative challenge and with start-up funding from San Mateo County and all 20 cities in it, OneShoreline was established by state legislation in 2020 as the first independent government agency in California to work across jurisdictional boundaries to plan for, and build regional resilience to, climate change. Five years after it opened its doors, OneShoreline is focused on four priorities.
Plan land use, private development, and public infrastructure for future climate-driven conditions in coordination with regional resilience projects
An enduring aspect of our work to date and going forward rests on having jurisdictions evaluate and approve new developments and public infrastructure projects with future conditions in mind rather than by looking in the rear-view mirror, as is too often the case. In 2021, OneShoreline worked with the City of Burlingame to incorporate sea level rise protection into a first-of-its-kind in the region zoning ordinance. In 2023, OneShoreline’s Board adopted Planning Policy Guidance with template text for general plans, zoning ordinances, and information on development agreements and project reviews, so that private and public assets can function for their intended lifespan and contribute to community resilience without having to undergo costly retrofits later. Now, in 2025 and 2026, we are working on a new countywide guidance document focused on future conditions planning for the key public infrastructure assets (stormwater and wastewater/water recycling systems, roads, parks, marinas, and utilities) that make our communities livable.
Advance projects that align long-term resilience for developed, natural, and recreational areas across jurisdictions; and economic resilience for property owners and renters
On the Bayside, OneShoreline continues to advance the Millbrae and Burlingame Shoreline Resilience Project, which aims to protect areas adjacent to the Bay shoreline and creeks that drain into it from flooding due to the higher tides and more extreme storms we see today, while enhancing nature and recreational opportunities. OneShoreline has also recently launched two efforts to transform creeks that have been long-standing liabilities into community assets along San Bruno Creek and within the Colma Creek watershed, which spans five cities. In 2025, OneShoreline will begin multi-jurisdictional shoreline planning to comply with new State requirements for the City of Brisbane (connected to San Francisco and South San Francisco, and in partnership with Caltrans) and the Cities of East Palo Alto, Menlo Park, Redwood City, San Carlos, and Belmont.
On the Pacific Coastside, OneShoreline is promoting a project to build resilience for a flood-prone wastewater treatment plant that serves Half Moon Bay and several communities to its north, as well as reducing the effects of coastal erosion; more information will be available on these efforts later in 2025. Please see our current project list for descriptions of many of our projects. Additionally, the affordability of, and access to insurance is a rapidly growing climate change impact in much of the U.S., including San Mateo County. Thus, OneShoreline is working with a national nonprofit specializing in addressing this issue, as well as researchers at Stanford to establish pilot projects for property owners and renters affected by the insurance crisis.
Provide early warning of, and reduce the impact of, today’s extreme storms made worse by rising tides
OneShoreline continues to operate, maintain, and expand the countywide Flood Early Warning System: an integrated network of stream, precipitation, and tide gauges for monitoring flood risk in real time. This system serves as an alert system and collects data for developing flood protection solutions. The flood monitoring webpage is accessible to both emergency responders and the general public. Improvements and expansion of the Flood Early Warning System are ongoing, with several new gauges coming online in 2025 and 2026.
Develop ongoing funding streams to build our collective resilience
The above three priorities reflect the need to address some of the most pressing challenges associated with climate change in our county. Because this need is only increasing, we are obliged to secure stable funding to both continue this work and leverage outside project financing. Please check back for future updates.
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Accomplishments to date
Bayfront Canal and Atherton Channel Flood Protection and Ecosystem Restoration Project
This project at the entrance to Bedwell Bayfront Park near Highway 84 and U.S. Highway 101 protects five mobile home parks and other housing and businesses from frequent, damaging flooding. Local agencies began planning this project in 2009, and in January 2020, OneShoreline assumed the role of lead agency. Over the subsequent 15 months, OneShoreline certified the California Environmental Quality Act (CEQA) document, secured federal and state environmental permits, signed a funding agreement for project construction and maintenance with Redwood City, Menlo Park, Atherton, and San Mateo County, and completed land agreements with several of these jurisdictions and a private landowner. Construction of this approximately $9.5 million project began in May 2021 and was completed in 2022 — on schedule and within the allocated budget. By diverting flows from Bayfront Canal to ponds managed by the U.S. Fish and Wildlife Service during major storm events, the new underground culvert system has demonstrated a reduction in flooding to these vulnerable areas along the Bay.
Hire staff and establish independent financial systems, policies, and procedures for a new government agency
A well-run government agency requires supportive and collaborative elected leadership and dedicated, competent staff. Within OneShoreline’s first six months of operation, the Board of Directors hired its first CEO, who in turn hired project and finance staff who established financial independence and new financial systems for long-term efficiency and growth. Evidence of sound financial stewardship is the fact that OneShoreline has been able to extend the three years of start-up funding from all jurisdictions in the county to nine years of operations, and it has provided millions of dollars to local projects to reduce flooding and enhance the environment.
New multi-jurisdictional projects to align long-term resilience for developed, natural, and recreational areas across jurisdictions
OneShoreline focuses on projects that have long-term meaningful objectives and achievable outcomes for multiple jurisdictions where there is local support and where OneShoreline has a clear role that adds value. Objectives for our work include protecting against extreme storms and a substantially higher sea level, restoring marshes and other natural features for their flood protection and environmental benefits, and incorporating trails for their recreational and connectivity benefits. With OneShoreline, project partners will establish common objectives and assumptions, share technical information, share environmental mitigations, share costs, and utilize public and private land rights to meet objectives.
OneShoreline’s first major multi-jurisdictional project is the Millbrae and Burlingame Shoreline Resilience Project which aims to (1) protect Millbrae and Burlingame from coastal and inland flooding and (2) improve shoreline trails and ecosystems. After securing $4 million in State funding, OneShoreline has completed several key milestones described on the project webpage. The Draft Environmental Impact Report (EIR) is planned for release in March 2026.
State-of-the-art Flood Early Warning System
OneShoreline continues to operate, maintain, and expand the countywide Flood Early Warning System: an integrated network of stream, precipitation, and tide gauges for monitoring flood risk in real time. This system serves as an alert system and collects data for developing stormwater management solutions. The flood monitoring webpage is accessible to both emergency responders and the general public. Four new dashboards have been created for the Atherton Channel, Belmont Creek, San Bruno Creek, and Colma Creek systems to provide concise points of reference for flood-prone watersheds.
System expansion has been completed through installation of a new monitoring station at Pescadero Creek on the Pacific Coastside, within the Green Hills Country Club golf course in Millbrae, and at San Bruno Mountain. New infrastructure is planned within Skylawn Memorial Park and along Pilarcitos Creek in Half Moon Bay, as well as creeks that flood portions of Atherton, Redwood City, and San Carlos.
Removing debris from flood-prone creeks
In December 2022 and January 2023, major storms caused significant flooding along several Bayside creeks in San Mateo County, mainly due to sediment and vegetation buildup reducing water flow capacity. As many creek floodplains span multiple jurisdictions, coordinated action is needed, and regulatory agencies favor a countywide approach to flood protection led by one entity. In June 2023, OneShoreline began the process to secure 5-year permits to enable the removal of debris in the most flood-prone locations of our creeks. Work to remove debris by OneShoreline, Caltrans, and the benefitting cities or County in San Bruno Creek, Belmont Creek, Cordilleras Creek, and Atherton Channel will begin as soon as permits are finalized.
Planning for what’s ahead rather than by looking in the rear-view mirror
In June 2023, OneShoreline’s Board adopted a first of its kind Planning Policy Guidance to plan land use, private development, and public infrastructure for future climate-driven conditions and with regional resilience projects. As of early 2025, five cities have incorporated aspects of the Guidance and several others are slated to as part of their updates to their general plan Safety Element.