In early 2008, the United States Army Corps of Engineers completed the initial preparation of an updated map which shows the areas around metropolitan Bakersfield which would likely be flooded in the unlikely case that the Dam should fail at Lake Isabella. As part of the maps provided the County, they have also included maps which show the anticipated depth and velocity of water and the anticipated time when the flows could reach the Bakersfield area if a failure of the dam occurred.


The Isabella Dam Failure Evacuation Plan provides the basic framework for response to an actual or potential failure of the Lake Isabella Dam. The plan supplements the Kern County/Operational Area and City of Bakersfield Emergency Operations Plans (EOPs) and will be implemented in conjunction with those EOPs.

Extensive research concerning hurricane-related evacuations indicates that for the evacuation of communities to be effective, residents must know which areas are at risk and must be persuaded to leave; the evacuation must commence prior to arrival of the threat; and transportation resources must be sufficient to move evacuees to safe areas.

When determining if people will evacuate, three factors are key:

  1. Actual and perceived vulnerability of their location,
  2. Whether or not they believe they have been told to evacuate by local officials, and
  3. The severity of the threat.

Aggressively communicating the evacuation recommendation tends to produce the desired action, although dissemination of the warning via the media is not usually sufficient. The best way to alert the public is for officials to go door-to-door. The second best method is to drive through neighborhoods announcing the evacuation recommendation over vehicle-mounted public address systems.

This plan calls for emergency notification information to be widely disseminated via all available means, including:

  • Activation of local emergency telephone notification systems (commonly referred to as "reverse 911" systems),
  • Local media,
  • Local specific needs agencies and groups,
  • Neighborhood drive-through by local law enforcement, and
  • Outdoor sirens where available.

This Evacuation Plan also calls for implementing an aggressive and ongoing public information program during the preparedness phase; advising the public of any potential problems with the dam and possible need to evacuate; and the issuance of a precautionary evacuation recommendation well in advance of the need to issue a general evacuation recommendation. This staged approach will facilitate the early evacuation and sheltering of most specific needs populations and many from the general population, thereby reducing the number of evacuees and the volume of traffic to be accommodated during the general evacuation recommendation.

Responding to a failure of Lake Isabella Dam and the resulting flood, including evacuation of more than one-quarter million people and sheltering 50,000 to 70,000 of the evacuees, will be a complex and resource-intensive operation, which will require close coordination among multiple local jurisdictions, disciplines and private and nonprofit agencies, as well as state and federal resources. If the same extraordinary level of coordination and cooperation demonstrated by all of these stakeholders during development of this plan is present when it must be implemented, the likelihood of a positive outcome will be assured.

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