Flood Zone Descriptions: Zone AE 10.5

There's only one such zone in Palo Alto. Flooding in the AE Zone is due to potential overtopping of the Bayfront levees in the event of an extremely high tide, particularly one that might be associated with a storm front.

This large zone is roughly bounded on the north by Embarcadero Road and on the south by the Mountain View city limits and includes everything easterly from roughly Middlefield, Ross and Louis Roads to San Francisco Bay. Originally, most of this area was tidal marsh and wetlands, but many years ago levees were built in the Baylands to drain the wetlands and allow the development of eastern Palo Alto. Because the levees lack required freeboard (additional height above the estimated high water level) and were not constructed in accordance with current engineering standards, FEMA does not consider these levees to be adequate protection from a high tide event that has a one percent (100-year) probability of occurring. The Flood Insurance Rate Maps were prepared under the assumption that the levees will overtop or fail and that the area in the AE 10.5 Zone will be flooded by tidal water to an elevation of ten and one-half feet above sea level (which is not the same as a depth of ten and one-half feet). Much of the residential area immediately west of the Bayshore Freeway is at only about six feet above sea level, meaning that the 100-year flood would reach a height of up to five feet above the ground.

If your property is near Greer Park, it may also be subject to flooding from San Francisquito Creek (see ZONE AH).

Last Updated: May 18, 2009