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<br />, <br /> <br />13. *** Big Thompson River below Estes Park, 7,350'), MM=65.8 <br />This site was used for a peak discharge estimate of the 1976 flood. <br />Peak discharge was 4,300 cfs (164 sq. mi.) and is near the upper limit <br />(margin) of the 1976 rainstorm and flood. <br /> <br />14. ***Lake Estes, 7,500', MM=65 <br />Lake Estes Reservoir (note the different riprap has been replaced on the <br />north toe of the dam as a result of erosion from the 1976 flood on Dry <br />Creek. <br /> <br />Note view to south of Long's Peak (elevation = 14,256 feet). <br /> <br />15. Estes Park Visitors Center (rest facilities), 7,500', 3:30 pm <br />a. Visit the streamflow-gaging station at "Big Thompson River at Estes <br />Park" (inflow to Lake Estes) adjacent to the BOR BT-Estes park <br />Powerplant. On July 31, 1976, rainfall was about 2 inches in Estes Park <br />and the Big Thompson River flow at Estes Park (drainage area = 137 sq. <br />mi.) was 457 cfs (about 300 cfs from rainfall and 157 cfs from snowmelt <br />runoff}. Are there spatial controls on maximum storm size? Did the 1976 <br />rainstorm (and other extreme rainstorms) end near 7,500 feet or are there <br />meteorologic reasons (or orographic) for the elevation limit of significant <br />rainfall-produced flooding? Discuss the recurrence interval of the 1976 <br />flood which ranged from 2 to 10,000 years. Discuss geomorphic, <br />precipitation, streamflow data to support the elevation limit of <br />significant rainfall flooding above 7,500 feet in Colorado (and streamflow <br />evidence in all Rocky Mountain States). <br />b. Discuss revised probable maximum precipitation values, risk-based <br />hydrologic assessments for dam safety and the impact on spillway design <br />floods in the Rocky Mountains. <br />c. Discuss this portion of the CR-BT Project. <br />d. Discuss the 1982 Lawn Lake Dam failure and computation of flood <br />discharges, attenuation, traveltimes, damages, etc. How much sediment <br />might have been deposited in the lake on July 15, 1982? Compared to <br />long-term average? How might flood warnings differ for dam-breach <br />flood? <br /> <br />6 <br />