Bay Area Dam Failure Inundation Hazards

	What is dam failure inundation?
	Interactive MAP - Dam Failure Inundation Areas (Allow pop-ups or you will have problems zooming in to your address) This map is summarized from maps prepared by dam owners and filed with California Office of Emergency Services to meet the requirements of SB 896, 1972. More info.
	View dam failure inundation hazard maps by city area in the Bay Area
	References

Upper San Leandro Reservoir showing original hydraulic fill dam and newer replacement dam (Source - J. Perkins, ABAG)

In hydraulic fills, materials are mixed with water and pumped to the fill location where they are poured into place. As the water drains, the sand settles in distinct layers that are prone to liquefaction failure. In the 1971 San Fernando earthquake, shaking and resulting liquefaction caused a major slide of the top thirty feet of the Lower San Fernando Dam. This hydraulic-fill dam was very close to completely failing. Eighty thousand people living downstream of the dam were immediately ordered to evacuate. Most hydraulic fill dams were deemed to be unsafe and have been replaced with other types of dams (usually rolled earth dams in the Bay Area). Various other standards for dam structures have been improved and applied.

California Department of Water Resources, Division of Safety of Dams FEMA National Dam Safety Program U.S. Bureau of Reclamation Data Web - Dams and Reservoirs U.S. Geological Survey - The Los Angeles Dam Story United States Society on Dams Association of State Dam Safety Officials National Performance of Dams Program (Stanford University)

ABAG, the Association of Bay Area Governments, is the regional planning and services agency for the nine-county San Francisco Bay Area.

This page was last updated 10/5/09 by jbp.