Alluvial fan flooding is increasingly important given the exponential urbanization of arid regions. However, flood behavior on alluvial fans in arid/semi-arid climates differs significantly from that of perennial rivers. Additionally, flood hazard maps differ widely depending on the methods, terminology, and spatial and temporal scales used. To improve understanding of arid system floods, and to ameliorate confusion for map users, we compared Federal Emergency Management Agency (FEMA) (CCRFCD, 2002), Natural Resource Conservation Service (NRCS) (Soil Survey Staff, 2007b), surficial geology (House et al., 2006a; House et al., 2006b) and flood hazard (House 2007) maps for the Ivanpah Valley, NV, the location of a planned new international airport. The FEMA map depicts areas that lie within the 100-yr flood hazard (Zone A) and those that do not (Zone X). The Order 3 NRCS survey shows 40 associations, each containing up to 5 distinct soil components and flood classes. The geologic map (1:50,000) contains 21 unique geomorphologic units. Of the 1,001.5 km² study area, 3.4 percent lies within FEMA Zone A, compared to 21.9 percent within the House (2007) Very High flood class alone. Soil components within the NRCS map are correlative to the surficial geology units and if both are combined the result is nearly an Order 2 soil survey. The House (2007) map provides the most useful information on flood hazards for land-use planning. This map depicts active drainage systems, their flowpaths, and the locations of specific drainage divides, indicating that geomorphology is the most important and unifying criterion for alluvial fan flood hazard determination.