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<br />::~[ATE OF C()LORAIJC <br /> <br />~ <br /> <br />COLORADO WATER CONSERVATION BOARD <br />Depal1ment of Natural Resources <br />721 State Centennial Building h. <br />131 3 5.herman Street <br />Denver. Colorado 80203 <br />Phone (303) 866-3441 <br /> <br />May 14, 1990 <br /> <br />Roy Romer <br />Governor <br />I. William MeDon,IIC <br />Director <br />David W. Walker <br />Deputy Dlrectol <br /> <br />Mr. Kenneth Bruch. Manager <br />City of Florence <br />300 W. Main <br />Florence. CO 81226 <br /> <br />Dear Mr. Bruch: <br /> <br />Following our meetings of April 17 and May 8. 1990. it <br />appears that there is some direction ,regarding the lOO-year <br />floodplain information for Oak Creek in the City of Florence <br />and Fremont County. Colorado. Presently there exists three <br />sources of flood hazard data for Oak Creek. These are: <br /> <br />o <br /> <br />Flood Insurance Study. Fremont County. Colorado <br />(Unincorporated Areas). dated September 29. 1989 <br /> <br />o <br /> <br />Flood Insurance Study. City of Florence. Colorado. <br />dated June 4. 1984 <br /> <br />o <br /> <br />U.S. P,rmy Corps of Engineers. Albuqu,~rque District. <br />Arkansas River Basin. Florence. Colorado. Design <br />Memorandum No.1. dated April. 1978. <br /> <br />The FIS. Fremont County and Corps of Engineers used a <br />lOO-year discharge of 20.500 cfs; whereas. the FIS. Fremont <br />County used a 100-year discharge of 22.500 cfs. <br /> <br />In addition to these hydrologic differences. there are also <br />d:,fferences ill the hydraulic and \Nate!: surface determination. <br />The three hydJ:aulic analyses all USE!d the Corps' HEC-2 program: <br />however. diffE!rent flow regimes werE! assumed for the respective <br />studies. The Corps of Engineers' 1978 hydraulic analysis <br />appears to be most representative of today's flow conditions. <br />Tbe attached hydraulic analysis table shows the comparisons of <br />tbree investic,ations. <br /> <br />The proposed agreement at our M,ay 8th meeting was to use <br />t::le Corps' hy,irologic and hYdraulic findings for the Oak Creek <br />floodplain which will require a LO~iR (Letter of Map Revision <br />and Physical J~ap Revisions). The basic dat.a for this <br /> <br />2479E* <br />