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boundary between two communities or two states, the allowable Tise in the BFE due to encroachment in one community or state is limited to O.S foot, unless a more stringent, State standard has been established. Floodways are developed for streams studied by detailed methods as part of the hydraulic analyses performed for those streams. The most common method FEMA uses to develop floodways is referred to as the "equal conveyance reduction method," in which the hydraulic computer model is modified so that equal amounts of hydraulic conveyance are eliminated from opposite sides of the 100-year floodplain until the allowable rise in the BFE IS reached. When it is necessary to develop floodways with specific configurations requested by the community, unequal reductions of conveyance area may be used. A floodway is a reasonable depiction of the area that must be kept open to convey floodwaters and is not necessarily the minimum area required to meet FEMA or State standards. Once adopted by the community, a particular floodway configuration becomes administratively established, as much the same as other community regulations do, and the limits of the floodway are intended to remain unchanged. However, in one situation, a community must request conditional approval of a floodway revision; in two other situations, a community may find it necessary to request a floodway revision. A community must request a floodway revision before permitting an encroachment into a regulatory floodway that would cause any rise in the BFE. Before FEMA can grant such a request, the community must apply to FEMA for conditional approval of the proposed project. The data the community must submit in support of such an application, and the procedures FEMA will follow in reviewing and responding to the application, are discussed in Chapter S, "Conditional Map Revisions." A community may request a floodway revision in the following situations: . When an Appeal or a Map Revision results in changes to effective BFEs . When, for good cause, the community wishes to shift the f100dway or change its configuration in some way Appeals and Map Revisions that result in changes to BFEs are generally supported by new or revised hydraulic analyses that involve modification of the original hydraulic computer model. (See Chapters 3 and 4.) Because the floodway is developed with that model and the floodway width depends on a specified rise in the BFEs, changes to floodways may be a part of any Appeal or Map Revision that results in changes to BFEs. A floodway revision request may be submitted during the 90-day appeal period or after the NFIP map on which the floodway is shown has become effective. Requests submitted during the appeal period will be handled as Protests. (See Appendix A.) Requests submitted after the effective date of the NFIP map will be handled under the map revision process. How to Request a Floodway Revision Because the community selects and adopts the floodway, all requests for changes to floodways must be made or approved by the community. FEMA will not revise a floodway without the approval of the community. Because the CEO of the community is responsible for ensuring that the community meets the obligation to regulate floodways, FEMA will work with the CEO or a local official designated by the CEO, such as a city planner or city engineer, in evaluating requests that involve changes to floodways. Therefore, any individual property owner, developer, or other person who wishes to request a map change that involves the floodway must submit the request to the CEO or the designated official. The CEO or other community official should review the request and, when forwarding it to FEMA, should state whether the community approves the requested change. 40