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accuracy of the mapping. Normally, the determination as to whether or not a development site is within the floodway limits should be corroborated with the appropriate local officials. the floodway hydraulics to mitigate the increase in the revised profile include: 1. Increase the flow conveyance area upstream and/or downstl development or structure; 2. Modify the flow alignment in the vicinity of the developmer 3. Reduce the conveyance roughness to increase the efficiency flood flow; 4. Increase the flow gradient in the vicinity of the structure; ani S. Modify design of the piers, abutments, and other floodway cc to reduce losses through the structure. The developer must conduct the water surface profi Ie analysis upstream and downstream of the development location to satisfad that no adverse effects occur if the above hydraulic modificatiol (ormed. Other de",'6<\ c.o<\"ideratio<\s besides water surface Ilrofiles dissipaters at the downstream end of the modification, ups downstream flow transitions into the existing channel, erosion st and sediment transportation, environmental impacts, and other fa ing to possible adverse impactS of hydraulic modifications in the the floadway development. 4-3. Development Results in Profile Rise Within Surcharge community may accept a revised floodway configuration to accor proposed development providing the NFIP limitations on increases flood profile are not exceeded. This is best accomplished when th, is first established. However, where the community is willing to established f100dway to support this option, the f100dway may be The community has the ultimate responsibility for demonstrat alternative floodway configuration meets the NFIP requirements. this responsibility is normally borne by the developer, who must a all of the data to substantiate the proposal. Floodway revisions a, even if the floodway width_does not change. The revisions must't the water surface profi Ie data sets used to develop the 100-ye; floodway but updated to reflect existing encroachment condit allows determination of the increase in the base flood elevation encroachments since the original f100dway was established. For the existing floodway surcharge equals 0.6 00 and the incremento surcharge from the proposed development is 0.2 00, the total surcharge of 0.8 00 is less then the allowable 1.000. Under these the community should request a revision to the f100dway boundar the developer to implement modifications so that no rise occurs the developer to mitigate the impact with all affected parties. 4-4 Development Results In Profile Rise Above Surcharge Lin way development that will result in a rise in the base profile allowable surcharge (normally one foot) should not be approvec 4. Floodway Development Impacts 4-1. Overview. The proposed development within the floodway boun- daries may result in one of three impacts with regards to the rise in the base water surface profile. They are: 1. Development complies with floodway regulations (no rise)' 2. Development results in profile increase, but within surcharge limits. 3. Development results in profile increase above the surcharge limits. Note: In some circumstances proposed development may result in no rise in the base water surface profile or in an increase that is within surcharge limits, nut wi)) also result in increases.1n water velodty. Such .lncreases may result in disapproval of the proposed f100dway development by the com- munity or a request for a lOMR from FEMA The developer must perform the technical studies required to demonstrate the impact ofthe proposed development. In general, the approval of floodway development is contingent on the development complying with the floodway regulations - no rise in the base water surface profile. However, if the proposed development results in a rise in the base profile, under some circumstances the community and FEMA may revise the f100dway boundaries or grant approval if the developer performs remedial actions. The hydraulic analysis data set used by FEMA in the FIS, modified to reflect the proposed developmental conditions, must be used to document the impacts of the proposed development. . no rise = 0.00 ft. 4-2. Development Complies With Floodway Regulations. This condition results from the proposed development complying with the NflI' no rise po\"KY for floodway development. No rise means a zero (0.00) increase along the floodway profile when comparing the proposed development floodway profile with the original floodway profile in the FIS. The project may normally be considered as being consistent with the regulatory standards if the hydraulic conditions can be improved so that no water surface elevation increase results for the proposed design. For function- ally dependent components, such as piers, which have a minor effect on the floodway water surface elevations, these modifications often are easily ac- complished. For alternatives where components of the proposed development encroach in the floodway and result in increased floodway profile elevations, more extensive modifications are normally required. Modifications used to alter 8