On December 14, 2010 FEMA issued a Letter of Map Revision (LOMR) revising the 2001 map to rezone certain areas from Zone AE to Zone A99.  Properties in Zone A99 are still required to carry flood insurance; however, some residents may be eligible for a reduced insurance premium.  Owners can contact their insurance agent to determine their current rate category and inquire if the new A99 zoning results in any discount.

On October 19, 2001 FEMA issued a Flood Insurance Rate Map (FIRM) for the City of San Mateo that placed parts of the City within a special flood hazard area.  This designation made flood insurance mandatory for properties within the hazard area.