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<br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />'I <br />I <br />!I <br />I <br />I <br /> <br />lflSTORY OF FLOODING <br /> <br />This section describes the flood histories and storm characteristics typical of the Cache La <br />Poudre River. Major flooding may occur from May to September. Flooding is usually the result <br />of intense rainfall with possible added amounts of water from snowmelt in May, June, July. <br />Stages can rise from normal flow to extreme flood peaks in 1 to 4 days. High stages can be <br />expected to last for several days. <br />Damaging floods that are on record in the area of the Cache La Poudre River occurred in the <br />following years: 1864,1876,1884,1904,1917,1923,1947,1949,1951, and 1965. Of these, the <br />1917 flood is the highest of record. <br /> <br />Table 1 <br /> <br />Historic Flood Peaks <br />Cache La Poudre River, Greeley, Colorado <br /> <br /> Year Date Peak Dischar~e (c.f.s.) <br />"Estimated 1917 June 24, 26 13,000 " <br /> 1923 June 17 Data not available <br /> 1947 June 23 4,050 <br /> 1951 August 5 3,760 <br /> 1965 June 19 3,480 <br /> <br />Information on historical floods on the Cache La Poudre River was obtained from a gaging <br />station maintained by u.s. Geological Survey at Greeley, Colorado. [Ref 1] <br />Recorded information on the recent flooding of 1995 is not yet available. <br /> <br />HYDROLOGIC ANALYSIS <br /> <br />A hydrologic analysis was not conducted as part of this study. Discharges for the study reach <br />of the Cache La Poudre River were reviewed to verifY the consistency of discharges used in other <br />floodplain studies conducted this area of the river. [Refs. 1,2, 3] <br />Table 2 summarizes the peak discharges and drainage areas used in this study based on a <br />review of the previous studies. <br /> <br />Table 2 <br />Sumrnarv of Discharges <br />(Values in cubic feet per second) <br /> <br /> Peak Dischar~es <br />Location 10 year 50 year 100 vear 500 year <br />Above Law Ditch 4,590 9,640 13,100 26,100 <br />Below Law Ditch 4,620 9,720 13,200 26,300 <br />Area of Study 4,506 9,530 13,200 26,300 <br />Above Coalbank Cr. 3,870 8,470 11,700 24,200 <br />Below Coalbank Cr. 3,900 8,540 11.800 24,400 <br /> <br />5 <br />