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For the streams 5 tudied floodplain boundary is (Exhibit 2). by approximate methods, only the 100-year shown on the Flood Insurance Rate ~lap 4.2 Floodways Encroachoent on floodplains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itself. One aspect of floodplain management involves balancing the economic gain from floodplain development against the resulting increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to assist local communities in this aspect of floodplain management. Under this concept, the area of the 100-year floodplain is divided into a floodway and a floodway fringe. The floodway is the channel of a stream, plus any adjacent floodplain areas that must be kept free of encroachment so that the lOO-year flood can be carried without substantial increases in flood heights. Minimum federal standards limit such increases to 1.0 foot, provided that hazardous velocities are not produced. 5.0 INSURANCE APPLICATION For flood insurance rating purposes, flood designations are assigned to a community based on the engineering analyses. These zones are as follows: insurance zone the results of Zone A Zone A is the flood insurance rate zone that corresponds to the IOO-year floodplains that are determined in the Flood cnsurance Study by approximate methods. Because detailed hydraulic analyses are not performed for such areas. no base flood elevations or depths are shown within this zone. Zone AE Zone AE is the flood insurance rate zone that corresponds to the lOa-year floodplains that are determined in the Flood Insurance Study by detailed methods. In most instances, whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone X Zone X is the flood insurance rate zone that corresponds to areas outside the 500-year floodplain, areas within 500-year floodplain, areas of laO-year flooding where average depths are less than I foot. areas of laO-year flooding where the contributing drainage area is less than 1 square mile, and areas protected from the 1 DO-year flood by levees. No base flood elevations or depths are shown within this zone. 11