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cross section. Between cross sections, the boundaries were inter- polated using orthophoto topographic maps at a scale of 1:4,800, with a contour interval of 2 feet (Reference 4). The 100- and SOD-year flood plain boundaries are shown on the Flood Insurance Rate Map (Exhibit 2). On this map, the 100-year flood plain boundary corresponds to the boundary of the areas of special flood hazards (Zones AE and AD), and the SOD-year flood plain bound- ary corresponds to the boundary of areas of moderate flood hazards. In cases where the 100- and SOD-year flood plain boundaries are close together, only the 100-year flood plain boundary has been shown. Small areas within the flood plain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data. 4.2 Floodways The floodway is the channel of a stream, plus any adjacent flood plain areas, that must be kept free of encroachment so that the 100-year flood can be carried without substantial increases in flood heights. The scope of work for this study did not include a floodway deter- mination for the streams studied. 5.0 INSURANCE APPLICATION For flood insurance rating purposes, flood insurance zone designations are assigned to a community based on the results of the engineering analyses. These zones are as follows: Zone AE Zone AE is the flood insurance rate zone that corresponds to the 100-year flood plains that are determined in the Flood Insurance Study by detailed methods. Whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected inter- vals within this zone. Zone AD Zone AD is the flood insurance rate zone that corresponds to the areas of lOO-year flooding where average depths are between 1 and 3 feet. Average whole-foot depths derived from the detailed hydraulic analyses are shown within this zone. 10