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are presented to local agencies as minimum standards that can be adopted directly or that can be used as a basis for additional floodway studies. The area between the floodw~y and 1-percent annual chance floodplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the floodplain that could be completely obstructed without increasing the water surface elevation of the 1-percent annual chance flood more than 1.0 foot at any point. Typical relationships between the floodway and the floodway g fringe and their significance to floodplain development are shown in Figure 1. For this Flood Insurance Study, floodways were not computed for the flooding sources. I ~- LIMIT OF FLOODPLAIN FOR UNENCROACHED 1% ANNUAL CHANCE FLOOD--~I _ _ FLOO~WAY FLOODWAY ,_~r_ ~ FRINGE y FLOODWAY-~~-- FRINGE STREAM CHANNEL FLOOD ELEVATION IHEN GROUND SURFACE CONFINED WITHIN F OODWAY ~ I I ENCROACHMENT ENCROACHMENT C D FILI FILL SURCMARGE' A _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ . B I AREA OF ALLOWABLE FILL ENCROACHMENT; RAISING FIOOD ELEVATION GROUND SURFACE WILL BEFORE ENCROACHMENT NOT CAUSE A SURCHARGE ON FLOOOPLAIN THAT EXCEEDS THE INDICATED STANDARDS LINE A- B IS THE FLOOD ELEVATION BEFORE ENCROACHMENT LINE C- D IS THE FLOOD ELEVATION AFTER ENCROACHMENT •SURCHARGE NO7 TO ExCEE~ 1.0 FOOT (FEMA REQUIREMENT) OR LESSER HEIGHT IF SPECIFIED BY STATE OR COMMUNITY. Figa~re 1 - Floodway Schematic . 5.0 INSURANCE APPLICATIONS 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 A Zone A is the flood insurance rate zone that corresponds to the 1-percent annual chance floodplains that are determined in the Flood Insurance Study by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no BFEs or depths are shown within this zone. 17