FEMA Flood Zone Overview


The National Flood Insurance Act of 1968 allows the Federal Emergency Management Agency (FEMA) to make flood insurance available to communities that adopt floodplain management regulations. The City of San Mateo has been a regular member of the National Flood Insurance Program since 1981. Historically, the City was not considered flood prone, but studies completed in the 1980s revised this assessment. In response, FEMA conducted a flood insurance study that designated areas north of Highway 92 for inclusion in a special flood hazard area. This designation became part of a Flood Insurance Rate Map (FIRM) that went into effect in 2001 and made flood insurance mandatory for properties within the special flood hazard area and optional for those in other areas. Since then, the City has undertaken a number of steps to modify FEMA’s designation and reduce residents’ insurance premiums.

City’s Efforts to Revise FIRM

FEMA requires communities to address tidal flooding (from the San Francisco Bay) and residual flooding (from interior sources like creeks) to remove areas designated as flood prone from the FIRM. In response, the City adopted a flood ordinance that meets federal standards for regulating development and improvements to properties in special flood hazard areas. The City also completed a comprehensive study of tidal and residual flood risks, flood protection measures to address these risks, and estimated costs and funding sources to implement improvements. In 2003, the City requested revision of the FIRM and provided FEMA information on planned or in-progress flood improvement measures. The City obtained the Conditional Letter of Map Revision (CLOMR) from FEMA in 2019. The CLOMR provides assurance that FEMA will revise the flood map upon completion of the levee improvements.

New Homes Entering "High Risk" Zones in April 2019

In 2018, FEMA performed a coastal study and released a preliminary map which became effective as of April 5, 2019. An estimated additional 176 additional addresses could be added to the high-risk zone, although FEMA is still in the appeal resolution stage of releasing the map. View the current (2019) FEMA Flood Zone Map to see which additional areas may be affected in the North Central neighborhood, highlighted in red.  For more information, read the following informational handouts: Fact Sheet for Properties Newly Mapped Into-High Risk Areas and Map Changes & Flood Insurance: What Property Owners Need to Know.

Formation of North Shoreview Assessment District

In March 2018, City Council approved the formation of the North Shoreview Assessment District to fund a portion of levee and pump station complete, is anticipated to revise the flood map and remove the newly-added areas above. In the meantime, property owners in the flood plain must still carry flood insurance.  

Click on the tabbed links below to read more about the project.

  1. Complete
  2. 2020 Updates
  3. Remaining

North Shoreview Levee and Pump Station Improvement Project

In 2019, the City received permits from the following agencies for the construction of the North Shoreview levee and pump station improvements:

  • California Department of Fish and Wildlife
  • Regional Water Quality Control Board
  • United States Army Corp of Engineers
  • State Historic Preservation Office
  • National Marine Fisheries Services
  • United States Fish and Wildlife Service


As of November 2019, our Public Works staff has secured the necessary easements for the construction of the North Shoreview Flood Zone Project, and obtained the Conditional Letter of Map Revision (CLOMR) from Federal Emergency Management Agency (FEMA). This letter provides assurance that upon project completion, properties will be removed from the FEMA flood map.

The City, also, submitted its final response to the San Francisco Bay Conservation and Development Commission (BCDC) to fulfill its requirements.

Ninety-five percent design of the North Bayfront Levee and Coyote Point and Poplar Pump Stations required to remove North Shoreview and North Central homes out of the High-Risk Zone AE. Began working with a consultant to start a study to evaluate the interest of an Assessment District to help fund the construction of those projects (2014-2016).

Completed construction of the South Bayfront Levee Improvement Project which resulted in the removal of approximately 4,000 properties from the FIRM and prevented an additional 4,000 from being placed on the FIRM. (2011)

Approved formation of an Assessment District to fund the South Bayfront Levee Improvement Project (2009)

Completed construction of the O’Neill Slough Tide Gate and Levee Improvements (2007)

Completed construction of the northern levee wall along San Mateo Creek (2004)

Enlargement of the box culvert under Highway 101 at 3rd Ave was completed by Caltrans (2004)

Completed construction of the Norfolk Bridge over San Mateo Creek (2002)

Completed construction of the southern levee wall along San Mateo Creek (2001)

Contacting the City

For questions or information about the City’s flood protection activities, please contact the San Mateo Public Works Department via email at publicworks@cityofsanmateo.org or call 650-522-7300.