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Flood Management

Levee Flood Protection Zones

A recent law passed in 2007, Water Code Section 9130, requires the Department of Water Resources (DWR) to prepare Levee Flood Protection Zone (LFPZ) maps by December 31, 2008; the maps shall, using the best available information, identify the areas where flood levels would be more than three feet deep if a project levee were to fail. DWR used information from several sources currently available, including FEMA floodplain maps, FEMA Q3 data, USACE's 2002 Sacramento and San Joaquin River Basins Comprehensive Study, and local project-levee studies. The law also states that DWR may periodically revise the maps to include updated information when that information becomes available. DWR is implementing an aggressive multi-year program to evaluate and delineate detailed floodplains for many of the areas protected by project levees. This effort includes new topography, hydrology, hydraulic models, and floodplain maps. This information will be used to update the initial LFPZ maps.

Under Water Code section 9110(b), "Levee Flood Protection Zone" means the area, as determined by the Central Valley Flood Protection Board or DWR, that is protected by a project levee. DWR delineated the LFPZs by estimating the maximum area that may be flooded if a project levee fails with flows at maximum capacity that may reasonably be conveyed. The maps should not be confused with Federal Emergency Management Agency's Flood Insurance Rate Maps used for the National Flood Insurance Program. They were prepared for different purposes and do not show the same type of flood hazard.