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. .. . . . 2 We reviewed the submitted data and the data used to prepare the effective FIRM for your community and determined that the proposed project meets the minimum floodplain management criteria of the NFIP. The submitted existing conditions HEC-RAS hydraulic computer model for Tributary D, dated November 2, 2000, based on updated topographic information, was used as the base conditions model in our review of the proposed conditions model for this CLOMR request. We believe that, if the proposed project is constructed as shown on the topographic work maps included in the report entitled "Aspen Creek Phase I Regional Drainage Facilities Construction Plans," prepared by Rocky Mountain Consultants, Inc., dated April 2000, and the data listed below are received, a revision to the FIRM would be warranted. The submitted existing conditions hydraulic analysis established water-surface elevations (WSELs) associated with the base flood along Tributary D. The discharge values used in the existing conditions hydraulic analysis were based on UDSWM2 model results from the aforementioned FHAD study. However, results from a new UDSWM2 model, dated August 22, 2000, that incorporated current land uses and the proposed development associated with the Aspen Creek project were used in the proposed conditions hydraulic analysis. The submitted proposed conditions HEC.RAS hydraulic model, dated September 12,2000, incorporated the aforementioned proposed project along Tributary D. As a result of the proposed project, the base flood WSELs for Tributary D within Boulder County will decrease compared to the existing conditions base flood WSELs. The maximum decrease in base flood WSEL, approximately I foot, will occur approximately 1,300 feet upstream of Sheridan Parkway. As a result of the proposed project, the width of the SFHA will decrease compared to the effective SFHA width. The maximum decrease in SFHA width, approximately 30 feet, will occur approximately 650 feet upstream of Sheridan Parkway. Upon completion of the project, your community may submit the data listed below and request that we make a final determination on revising the effective FIRM and FIS report. . Detailed application and certification forms, which were used in processing this request, must be used for requesting final revisions to the maps. Therefore, when the map revision request for the area covered by this letter is submitted, Form 1, entitled "Revision Requester and Community Official Form," must be included. (A copy of this form is enclosed.) . The detailed application and certification forms listed below may be required if as.built conditions differ from the preliminary plans. If required, please submit new forms (copies of which are enclosed) or annotated copies ofthe previously submitted forms showing the revised information. Form 3, entitled "Hydrologic Analysis Form" Form 4, entitled "Riverine Hydraulic Analysis Form" Form 5, entitled "Riverine/Coastal Mapping Form" Form 6, entitled "Channelization Form" Form 7, entitled "Bridge/Culvert Form"