The County has adopted County Floodway Maps for various watercourses throughout Los Angeles County. The County Floodway Maps depict the areas subject to inundation during a large storm event (floodplain) and the areas within the floodplain where flows are deepest and fastest and where development is generally restricted (floodway). The purpose of the County Floodway Maps provide a tool to alert the public of potential flood hazards and help landowners and County regulators to plan development projects in a manner that minimizes flood damage both onsite, to neighboring properties and to the downstream environment.
The County undertakes map revisions is to document the changes in the physical environment, in both the floodway and floodplain of the County Capital Flood event, that have occurred since the maps were completed, as a result of one or more of the following:
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Changes in topography caused by fire and flooding;
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More precise mapping made possible by additional data for precipitation and sediment transport; or
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Updates to hydraulic analysis models, such as those of the U.S. Army Corps of Engineers.
Santa Clara River County Floodway Map Revisions